U.S. DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

(Formerly National Bureau of Standards)

NIST Special Publication 250 Calibration

Services

Users Guide

1989

B—imiii m tPiiUMWiiMHiiii III mmmmmmmsmmm^i^^mm

For Information, Phone

301-975-2002

NIST

Calibration

Services

Users Guide

1989 Edition

Joe D. Simmons, Editor

Office of Physical Measurement Services

National Institute of Standards and Technology

Gaithersburg, MD 20899

NIST Special Publication 250

Revised January 1989

(Supersedes 1986 Edition)

U.S. Department of Commerce

C. William Verity, Secretary

Ernest Ambler, Acting Undersecretary for Technology

National Institute of Standards and Technology

Raymond G. Kammer, Acting Director

For Information, Phone

301-975-2002
National Institute of Standards and Technology

Special Publication 250, 1989 Edition

Natl. Inst. Stand. Technol., Spec. Publ. 250, 1989 Ed.,

208 pages (Revised Jan. 1989)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1989

For sale by the Superintendent of Documents,

U.S. Government Printing Office, Washington, DC 20402

U.S. Government Printing Office

Washington: 1989
Foreword

The NIST Calibration Services Users Guide provides detailed descriptions of the currently available NIST calibration services, special-test services, and measurement as- surance programs. This document is a revised edition of NBS Special Publication 250.

It describes the NIST services available as of the third quarter of 1988 and reflects a number of important changes since the 1986 edition was published. A detailed description is given of each measurement service, and a large number of NIST technical ex- perts are cited (who may be contacted for further information concerning services or measurement problems). Future editions will be published periodically as NIST ser- vices change.

This document also presents a detailed description of a number of Measurement Assurance Program (MAP) services. These are carefully designed quality control pro- grams for critical measurements that allow the user to achieve a high level of

confidence that the measurements being made in the user's laboratory are consistent

with national standards and adequate for intended use. MAP services are available for some basic measurement quantities (e.g., laser power and energy).

A Fee Schedule for the services described in this Users Guide is published as re- quired. It lists current prices for the services described here. NIST will notify users of

changes in services or proposed changes in services by means of announcements in the

Fee Schedule. In addition, information about upcoming NIST Measurement Seminars

is announced there. It is important that you refer to the current issue of the Fee

Schedule in order to have up-to-date information with respect to NIST contacts. A companion document to this guide is NIST Special Publication 260, NIST Stan- dard Reference Materials Catalog. This document describes over 900 Standard Refer- ence Materials (SRM's) certified by NIST for use in industrial quality control,

materials testing, environmental testing, and clinical testing applications. A copy of

SP 260 may be obtained by calling (301) 975-6776.

The Office of Physical Measurement Services welcomes suggestions on how this publication can be made more useful to those who rely on NIST physical measure- ment services. Suggestions are also welcome concerning needs for new calibration

services, measurement assurance programs, or other measurement services.

Joe D. Simmons

Office of Physical Measurement Services

iii
Abstract

The National Institute of Standards and Technology (NIST) Calibration Services

Users Guide provides detailed descriptions of currently available NIST calibration ser- vices, measurement assurance programs, and special-test services. The following measurement areas are covered: (1) dimensional; (2) mechanical, including flow, acoustic,

and ultrasonic; (3) thermodynamic; (4) optical radiation; (5) ionizing radiation; and

(6) electromagnetic, including dc, ac, rf, and microwave. A separate Fee Schedule

is issued as required, providing current prices for the services offered, updates on

points-of-contact, and information on measurement seminars.

Key words: calibration; measurement assurance; measurement services; standards;

traceability.

iv
Acknowledgments

Many NIST staff members contributed to the development and preparation of this guide. Over 50 members of the NIST technical staff contributed data and information

that have been incorporated into the guide. Special thanks should go to the SP 250

committee, which included Dan Flynn, John Mayo-Wells, Sylvia Ramboz, Roald

Schrack, and Hratch Semerjian. Joanne Marshall served as production manager for much of the production, and Jennie Covahey coordinated the preparation of the final document. Editorial assistance was provided by Cheryl Williams, who did an excellent job in typing, proofreading, and assisting with the photos. Kathy Hillen, NIST

Boulder, arranged for the Boulder photographs and verifications. Margaret Musick and

Verna Moore assisted with corrections to the drafts. NIST Publications Production

staff made many valuable suggestions and typeset the final draft.

The Editor
List of Tables

Table Page

1. Estimated Systematic Uncertainties of Piston Gage Calibrations

in Gage Mode 47

2. Thermometer Calibration Uncertainties 53

3. Primary Standard Measurement Capabilities 78

4. Measurement Capabilities 79

5. Low-Level MAP Transfer Standards 80

6. Pulsed CO, Calibrations 80

7. Specifications for Calibration of Gamma-Ray Emitting

Solutions Which Are Submitted for Calibration 84

8. Specifications for Calibration of Gamma-Ray Solution Sources 85

9. Specifications for Calibrations Using the lira Proportional

Counter and the 0.877a Defined Solid Angle Counter 85

10. Specifications for Special Tests of Beta-Particle-Emitting

Solution Sources 86

1 1 . Irradiation Parameters for Fission Spectrum and

Maxwellian Thermal Neutron Fields 87

12. X-Ray Beam-Quality Parameters 92

13. Calibration Uncertainties for DC Resistance Standards 101

14. AC-DC Difference Calibration Service 122

15. Specifications and Estimated Uncertainties for Low-Frequency

TVC Services 125

16. Specifications and Estimated Uncertainties for High-Frequency

TVC Services 125

17. Specifications and Estimated Uncertainties for Peak-to-Peak

Detector Services 126

18. Specifications and Estimated Uncertainties for RF

Micropotentiometer Calibrations 126

19. Specifications and Estimated Uncertainties for Data Converter

Calibrations 130

20. Available Values of the Parameters for Routine Wattmeter

and Watthour Meter Testing 146

21. Summary of NIST Standard Field Strength Facilities 169

22. NIST Impulse Generator Spectrum Amplitude Measurement Service

Capabilities 171

23. Limits of Uncertainty for Calibration of Fast Repetitive

Baseband Pulse Parameters 171

vi
List of Figures

Figure Page

1. Accuracy of Length Measurements at NIST 8

2. Precision of Angle Calibrations for Master

Angle Gage Blocks and Polygons 15

3. Systematic Uncertainty of NIST Measurements for Air

Flow Rate Standards 24

4. Systematic Uncertainty of NIST Measurements for Water

Flow Rate Standards 24

5. Systematic Uncertainty of NIST Measurements for Liquid

Hydrocarbon Flow Rate Standards 25

6. Systematic Uncertainty of Airspeed Measurements for Calibration of Airspeed Indicators 27

7. NIST Precision of Weighing for Mass Standards

Ranging from 10^* to 10 Kilograms 30

8. Uncertainties of NIST Low Pressure and Vacuum Standards 50

9. Uncertainties for NIST Calibration of Temperature

Measuring Instruments 53

10. NIST Uncertainties for Measurements of Humidity

Standards with Atmospheric Air at Atmospheric Temperature 62

11. Uncertainties for NIST Spectral Radiance Calibrations 71

12. Uncertainties for NIST Spectral Irradiance Calibrations

of Type FEL Lamps 72

13. Uncertainties of NIST DC Voltage Measurements 114

14. NIST Uncertainties for AC Voltage Measurements 120

15. Uncertainty for NIST Data Converter Test System

for Resolutions from 12-18 Bits 130

16. Estimated Total Uncertainties of the NIST Phase

Angle Calibration Standard 142

vii
Contents

Chapter 1 Policies

A. Introduction 1 B. Questions and Inquiries 1 C. Fees , 1 D. Types of Services 1 E. Criteria 2

F. Reports of Test Results 2 G. References to NIST in Advertisements 2 H. Traceability 2

I. Disclaimer 3

J. Ordering and Scheduling 3 K. Purchase Order 3 L. Shipping, Insurance, and Risk of Loss 4

M. Special Instructions for Foreign Customers 4

Chapter 2—

Dimensional Measurements

A. Length Measurements 7 100 IOC Gage Blocks

10020C Line Standards

10030C Surveying and Oil Gaging Tapes

10040S Special Tests of Surveying Leveling Rods

10050S Special Tests of Length Standards

10060S Special Tests of Sieves

B. Diameter Measurements 10 IIOIOS Special Tests for Plug Gages: External

Diameter Standards

11020C Measuring Wires for Threads and Gears

11030S Special Tests of Spherical Diameter Standards: Balls 11040S Special Tests of Internal Diameter Standards:

Ring Gages

11050S Special Tests of Length and Diameter

11060S Special Tests of End Standards

11070S Special Tests of Step Gages

11080S Special Tests of Thread Measuring Wires

C. Complex Dimensional Standards 12 12010C API Threaded Plug and Ring Gages

12020S Special Tests of Plain Conical Plug and Ring Gages

12030S Special Tests of Threaded Plug and Ring Gages

12040S Special Tests of Calipers and Gages

12050S Special Tests of Micrometer Screws and Dial

Micrometers

12060S Special Tests of Penetration Needles

12070S Special Tests of Two-Dimensional Gages

viii
D. Optical Reference Planes & Roundness Standards 14 1301 OS Special Tests of Optical Reference Planes (Flats)

13020S Special Tests of Roundness

13030S Special Tests of Roundness Calibration Specimens

E. Angular Measurements 15 14010C Angle Gage Blocks

14020S Special Tests of Optical Polygons

14030S Special Tests of Rotary and Indexing Tables

14040S Special Tests of Wedges

14050S Special Tests of Autocollimators

14060S Special Tests of Angle Generators

F. Surface Texture 17 150 IOC Roughness Calibration Specimens

15020C Surface Roughness Comparison Specimens

15030C Step Height Measurements

G. Hydrometers 19 160 IOC Reference Standard Hydrometers

H. Volume and Density 20

170 IOC Volume Standards

17020S Special Tests of Volume Standards

17030S Special Tests of Density: Solids

17040S Special Tests of Density: Liquids

Chapter 3—

Mechanical Measurements

A. Flow Rate Measurements 23

180 IOC Single Turbine Meters

18020C Tandem Turbine Meters

18030C Flow Rate Meters (Direct Reading in Flow

Rate Units)

18040C Head Class Flow Measurement Devices

18050S Special Tests for Liquid and Gas Flow Rates

B. Flow Measurements at Cryogenic Temperature 26

18800S Special Tests of Cryogenic Liquid Flow

C. Airspeed Measurements 27

190 IOC Pitot-Static Tubes (3 to 150 mph)

19020C Low Airspeed Measurements (15 to 2,000 fpm)

19030S Meteorological Airspeed Instrumentation (3 to 150 mph)

19040S Special Tests of Airspeed Instruments

ix
D. Mass Standards 29

22010C-22030C. . .Weight Sets (1 mg to 30 kg)

22040C-22110C. . .Single Weights (1 mg to 30,000 kg)

22130C-22150C. . .Single Weights for Deadweight Pressure Testers 221 70S Special Mass Measurement Services

22180M Measurement Assurance Program for Mass

E. Force Measurements 33

23010C-23240C. . .Force Transducers (to 1,000,000 Ibf, 1 or 2 Modes)

23250C Force Transducers (over 1,000,000 Ibf) 23260S Special Tests of Force Transducers

F. Vibration Measurements 35

24010C-24030C. . .Vibrations (Pickup Sensitivity, 2 to 10,000 Hz)

24040S Special Shock Measurement Services

24050S Special Tests of Pickup Sensitivity

24060S Special Vibration Tests, by Prearrangement

G. Acoustic Measurements 37

25010C-25020C. . .Pressure Response: WE Type 640AA

Microphones or Equivalent

25030C-25040C. . .Pressure Response: Tokyo Riko Type ECL

MR11 2, or Equivalent Half-Inch Microphones

25050C Free-Field Response: Tokyo Riko Type ECL

MR112, Bruel & Kjaer Types 4133, 4134, 4165,

4166, or Equivalent Half-Inch Microphones

25060S Special Tests of Acoustic Devices

25070S Special Tests of Earphones

H. Ultrasonic Reference Block Measurements 40

26030S-26040S . . .Special Tests of Area/Amplitude Aluminum

Reference Blocks

26050S-26060S . . .Special Tests of Distance/Amplitude

Aluminum Reference Blocks

26070S Special Tests of Amplitude or Velocity

Reference Blocks

I. Ultrasonic Transducer Measurements 42

26100C Ultrasonic Transducer Power Output;

Radiation Pressure

261 IOC Ultrasonic System Power Output; Calorimeter

26120S Special Tests of Ultrasonic Transducers

J. Acoustic Emission Transducer Measurements 44

26200C Acoustic Emission Transducer Amplitude and

Phase Sensitivity versus Frequency

262 lOS Special Tests of Acoustic Emission

Transducers and Sensors

X
Chapter 4—

Thermodynamic Quantities

A. Pressure Measurements 47

29010C Deadweight Piston Gages

29020C Controlled Clearance Piston Gages

29030C Pressure Gages and Transducers

2903 5C Mercurial Barometers and Manometers

29040S Special Tests of Pressure Gages

B. Low-Pressure, Vacuum, and Leak Measurements 49

30010C-3001 IC. . .Absolute Low-Pressure Transducers

30020C-30021C. . .Differential Low-Pressure Transducers

30030C-30031C. . .Molecular Drag Gages

30032C-30034C. . .Ionization Gages

30040S Special Tests of Low-Pressure Gages

30050S Special Tests of Vacuum Gages

30060S Special Tests of Leak Artifacts

C. Laboratory Thermometers 52

31010C-31060C. . .Laboratory Thermometers

31070C Calorimetric Thermometers

31080C Beckmann Thermometers

31100S Quantity Tests of Liquid-in-Glass Thermometers

31110S-31160S . . .Special Tests of Thermometers

31260S Special Thermometry Services, by Prearrangement

D. Thermocouples, Thermocouple Materials, and 54

Pyrometer Indicators

32010C-32044C. . .Type S, R, B, E, J, K, N, and T, Measured with

Standard Thermocouples Covering 0-1750 °C

32070C Thermocouple Materials Tested against Pt Standard, 4 to 15 Points

32090C Type S Measured with Freezing-Point Standards

(0-1450 °C)

32100C Pyrometer Indicators (Portable Potentiometers,

First Dial or Range)

321 10C-32147C. . .Thermocouple Materials Tested against Pt Standard with PRT-Varian Temperature

Ranges

32150S Special Tests of Thermocouples and Thermocouple

Materials

xi
E. Resistance Thermometry

33010C-33020C. . .Long Stem Platinum Resistance Thermometers

33030C Calorimetric Type PRT (-50 to +150 °C)

33040C-33050C. . .Capsule Type Platinum Resistance Thermometers

33060S Special Tests of Germanium Resistance

Thermometers

33100S Special Tests of Resistance Thermometers

331 lOS Special Tests of Thermometric Fixed-Point

Devices

33120M Measurement Assurance Program for Temperature

F. Radiation Thermometry 60

35010C-35040C. . .Optical Pyrometers

35050C-35060C. . .Ribbon Filament Lamps (800 to 2300 °C)

35070S Special Tests of Radiation Pyrometers

G. Humidity Measurements 62

36010C-36020C. . .Dew-Point Hygrometers

36030C Electric Hygrometers

36040C Electrolytic Hygrometers

36050C Aspirated Hygrometers

36060C Pneumatic Bridge Hygrometers

36070S Special Tests of Humidity

Chapter 5—

Optical Radiation l\/leasurements

A. Photometric Measurements 65

37010C-37070C. . .Luminous Intensity Standard (100-1000 W Frosted

Tungsten Lamp, 90-1400 candelas, 2700 K and

2856 K color temp.)

37080C Luminous Flux Standards (25 W Vacuum Lamp)

37090C-37120C. . .Luminous Flux Standards (60-500 W, Gas-Filled

Lamps)

37130C Luminous Flux Standards (Miniature Lamps)

37140C Airway Beacon Lamps

37170C Opal Glass Luminous Directional Transmittance

Standards

371 SOS Special Photometric Tests

B. Spectrophotometric Measurements 67

38010C-38040C. . .Spectral Transmittance Filters 38050C Wavelength Standards (Holmium Oxide Glass)

38060S Special Tests of Spectral Transmittance and

Reflectance

38070M-38074M. .Measurement Assurance Program for Retroreflectance

38080M Measurement Assurance Program for Transmittance

38090S Special Tests of X-Ray Photographic Step Tablets

38100S Special Tests of Microcopy Resolution Test Charts

xii
C. Radiometric Measurements 71 39010C-39030C. . .Spectral Radiance Ribbon Filament Lamps

39040C-39045C. . .Spectral Irradiance Quartz-Halogen Lamps

(250-2400 nm)

39050C Spectral Irradiance Deuterium Lamps

(200-350 nm)

39060S Special Tests of Radiometric Sources

39070C Photodiode Spectral Response Rental Package

39080S Special Tests of Radiometric Detectors

D. Radiometric Standards in the Far Ultraviolet 74

D.l Standard Sources 40010C Spectral Irradiance Standard, Argon Mini-Arc

40020C Spectral Radiance Standard, Argon Mini-Arc

40030C Spectral Irradiance Standard, Deuterium Arc Lamp

40040S Special Tests of Radiometric Devices in the Near and

Vacuum Ultraviolet

D.2 Standard Detectors in the Far Ultraviolet 76

40510C-40561C. . .Detector Standard, Windowed and Windowless

Photodiode

40599S Special Tests on Detectors from the Near Ultraviolet

to the Soft X-Ray Region

E. Laser Power and Energy 78

421 IOC Laser Power and Energy Meter Calibrations

42120M Laser Power and Energy Measurement

Assurance Program

42130C Optical Fiber Power Meter Calibrations

42140M Optical Fiber Power Meter Measurement

Assurance Program

42150M Low-Level Laser Measurement Assurance

Program

42160C Pulsed 10.6-jLim Laser Calibrations

421 70S Special Tests for Laser Power and Energy

Meters

421 808 Special Tests for Optical Fiber Power Meters

Chapter 6—

Ionizing Radiation Measurements

A. Radioactivity Sources 83

43010C-43020C. . .Gamma-Ray-Emitting Radionuclides in Solution

43030C-43050C. . .Alpha-Particle-Emitting Solid Sources

43060S-43070S . . .Special Tests of Beta-Particle-Emitting Solution

Sources

43090S Special Tests of Alpha-Particle-Emitting Solid

Sources

xiii
B. Neutron Sources and Neutron Dosimetry

44010C-44020C. . .Radioactive Neutron Sources

44060C Personnel Protection Instrumentation,

Californium Source Bare and Moderated

44070C Activation Detector Dosimetry, Thermal

Neutrons

44080C Activation Detector Dosimetry, Californium

Fission Neutrons

44090C Activation Detector Dosimetry, "^'U Cavity

Fission Source

44100S Special Tests of Neutron Sources and Dosimeters

C. Dosimetry of X Rays, Gamma Rays, and Electrons

C 0 Special Instructions for Using Electron and Photon Dosimetry

Calibration and Test Services 90

C.l X-Ray and Gamma-flay Measuring Instruments 91 46010C-4601 IC. . .Radiation Detectors—Calibration/Correction Factor

46020C-46021C. . .Passive Dosimeters

46030S Special Tests of High-Gain Electrometers—Charge

Sensitivity

46040S Special Tests of X-Ray Penetrameters,

Ardran-Crookes Type

46050S Special Tests of X-Ray and Gamma-Ray Measuring

Instruments C.2 Gamma-Ray Sources, Beta-Particle Sources, and Measuring Instruments 93

47010C-47011C. . .Gamma-Ray Sources

47030C-47035C. . .Beta-Particle Sources

47036C Ionization Chambers

47040S Special Tests of Gamma-Ray and

Beta-Particle Sources

C.3 Dosimetry of High-Energy Electron Beams 94

48010M-4801 IM. .Irradiation of Ferrous-Ferric Dosimeters

48020S Special Tests of Electron-Beam Dosimeters

D. Dosimetry for High-Dose Applications 96

490 IOC Calibration Irradiations of Customer-Supplied

Dosimeters Irradiated with ^°Co Gamma Rays

49020C-49030C. . .Dose Interpretation of NIST Transfer

Dosimeters Irradiated by Customer

49040S-49041S . . .Special Tests of Dosimeters by Reading with

Spectrophotometer

49050S Special Measurement Services for Dosimeter

Response and Dose Distributions

XIV
Chapter 7—

Electromagnetic Measurements

A. Resistance Measurements

A.l DC Resistance Standards and Measurements 99

51100S Special Resistance Measurement Services,

by Prearrangement

51110M Measurement Assurance Program Services for Resistance

51130C Standard Resistor, Thomas-Type, 1 H

51131C Standard Resistor, Evanohm Wirewound

High Precision, 10 kft 51132C-51138C. . .Standard Resistor, Four-Terminal, 0.0001-100 fi 51139C-51154C. . .Standard Resistor, 1 kH-l Tft

51 160C-51 163C. . .Standard Resistor, for Current Measurements

(Shunts)

A. 2 High- Voltage Standard Resistors 103

5 12 IOC High-Voltage Standard Resistors

A. 3 High-Frequency Standard Resistors 104

51310S High-Frequency Standard Resistors,

Two-Terminal

A. 4 AC Resistors 105 51410S Special Tests of AC Resistors, by Prearrangement

B. Impedance Measurements (Except Resistors)

B. 1 Low-Frequency Capacitance and Inductance Measurements and Standards 106

521 lOS Special LF Impedance Measurements,

by Prearrangement

52130C-52131C. . .Standard Fixed, Fused-Silica, Dielectric Capacitor

52140C-52141C. . .Fixed Three-Terminal, High-Precision

Standard Capacitor with Coaxial Connectors

52150C Physical Tests to Qualify Three-Terminal Air

Capacitors for Measurement

52160C-52161C. . .Fixed Three-Terminal Standard Capacitor with

Coaxial Connectors

52170C-52171C. . .Two- or Three-Terminal Solid Dielectric Standard

Capacitor

52180C-52181C. . .Fixed Inductor, Self or Mutual

B.2 High-Frequency Standard Capacitors and Inductors 110

52210S-52211C . . .Two-Terminal, Low-Loss, Standard Capacitors

52220S-52221C . . .Three-Terminal, Low-Loss, Standard Capacitors

52222S-52223S . . .Three-Terminal (MacLeod and Hanopol)

Capacitors

523 lOS Two-Terminal, High-Q Standard Inductors

B.3 Power-Frequency Capacitors 112 52400C Power-Frequency Capacitors

B.4 Q-Standards 113 52710C-52711C. . .Inductive Q-Standards

XV
C. Voltage Measurements

C.l DC Voltage Measurements and Standards 114

5311 OS Special DC Voltage Measurements,

by Prearrangement

53120M Measurement Assurance Program for DC Voltage

53130C-53131C. . .Saturated Standard Cells

53140C Platinum Resistance Thermometer Temperature

Determination for Standard Cell Calibration

53150C Unsaturated Standard Cells 53160C-53161C. . .Tests of Solid-State Voltage Reference Standard

53180S-53190S . . .Special Handling

C.2 AC Voltmeters and Sources 119

53200S Special Tests of High-Accuracy AC Voltmeters

and Sources, by Prearrangement

C3 AC-DC Thermal Voltage and Current Converters (to 1 MHz) 121 533 lOS Spfcial AC-DC Measurement Services,

by Prearrangement

53340C-53341C. . .AC-DC Thermal Voltage and Current Converters

C.4 RF-DC Thermal Voltage and Current Converters (100 Hz-1 GHz) 124

53405S Special Tests of AC Thermal Voltage

Converters, by Prearrangement

53410C-53415C. . .Low-Frequency TVC Calibrations

53420C-53421C. . .High-Frequency TVC Calibrations

53430S-53431S . . .Peak-to-Peak Detector Calibrations

53440S Special Tests of RF Micropotentiometers,

by Prearrangement

53441C RF Micropotentiometer Calibration

53445S Special Calibration of RF Micropotentiometer

C.5 Data Converters 128

53500S Special Data Converter Services,

by Prearrangement

535 IOC A/D or D/A Converters, Linearity Errors, 10-Bit

Correction Coefficients, and Superposition Errors 53520C A/D or D/A Converters, Differential Linearity Errors 53530C A/D Converter, Equivalent RMS Input Noise

53540S A/D or D/A Converters, Offset and Gain Errors

Relative to Legal Volt

D. Precision Ratio Measurements

D.l Inductive Dividers 132

5411 OS Special Ratio Measurements and Tests of Inductive

Voltage Dividers, by Prearrangement

54120C-54131C. . .Inductive Voltage Dividers

D.2 Resistive Dividers 134

542 IOC Resistor and Resistive Dividers, Total Resistance or Voltage Ratio

5421 IS Special Tests of Resistor and Resistive Dividers

at Direct Voltage Levels, by Prearrangement

xvi
542 12C Resistor and Resistive Dividers at 60 Hz,

Voltage Ratio and Phase Angle

54213S-54214S . . .Special Tests of Resistor and Resistive

Dividers

D.3 Capacitive Dividers 137

54310S-5431 IS . . .Special Tests of Capacitive Dividers

D. 4 Mixed Dividers 1 3 8 54410S Pulse Voltage Measuring Systems, Including

Kerr Cells

D.5 Voltage and Current Transformers 139

54510C-54513C. . .Voltage Transformers, Ratio and Phase Angle

54520C-54522C. . .Current Transformers, Ratio and Phase Angle

54600S Special Tests of Dividers and Transformers,

by Prearrangement

E. Phase Measurements

E. 1 Phase Meters and Standards 142

55110S Special Tests of Phase Standards and

Related Instruments, by Prearrangement

55120C-55141C. . .Phase Meters

E.2 Very-High-Frequency Omnidirectional Range (VOR) Measurements 144

55210C-55211C. . .VOR Bearing-Angle Indicators

55220C-55221C. . .VOR Generators

55230S Special VOR Tests

F. Power and Energy Measurements, Low-Frequency 146

561 lOS Special Tests of AC-DC Wattmeters,

by Prearrangement

56120C-56121C. . .Wattmeter Calibrations at Power Frequencies

56200C-56203C. . .Watthour Meter, Determination of Percentage

Registration at 60 Hz

562 lOM Measurement Assurance Program for Watthour

Meters

G. Microwave Measurements

G. 1 Power Meters, RF and Microwave 149

61 1 108-61 128S . . .Coaxial Power Meters, Combinations of Calibration

Factor, Effective Efficiency Factor, and Reflection

Coefficient at Specified Frequencies in Range

0.1 MHz to 18 GHz

61 140S-61 155S . . .Rectangular-Waveguide Power Meters,

Combinations of Effective Efficiency,

Efficiency Factor and Reflection Coefficient

within Specified Frequency Bands Covering

2.6-96 GHz

61190S Special Microwave and RF Power Measurement

Services, by Prearrangement

xvii
G.2 Attenuators, RF and Microwave 153

61210S Coaxial Fixed and Variable Attenuators,

0.1 to 18 GHz

61211C Coaxial Fixed and Variable Attenuators, Measured

at 30 MHz

61215C Waveguide Circular (Below Cutoff) (Piston)

Attenuator, Coaxial Connector, Measured at 30 MHz

61220S Special Attenuation Measurements in Range 30 kHz

to 10 MHz, GR874 Connectors

61230S Variable Rectangular Waveguide Attenuators,

Attenuation Difference, WR28-WR187

Waveguide Bands

61240S Special Attenuation Measurements of Three-Port

and Two-Port Devices at 1.25 MHz

61250S Special Attenuation Measurements, by

Prearrangement

G.3 Coaxial and Waveguide Terminations, Reflection Coefficients 156

613 lOS Complex Reflection Coefficient, Impedance, and

Voltage Standing Wave Ratio of Coaxial

Terminations, 0.1 to 18 GHz

61320C Magnitude of Reflection Coefficient of Rectangular

Waveguide Reflectors (Mismatches) with

Standard Flange Connectors at Frequencies

within WR28-WR187 Waveguide Bands

6 132 IS Special Reflection Coefficient Measurements,

by Prearrangement

61330S Magnitude of Reflection Coefficient of

Nonreflecting Waveguide Ports and Matched

Loads at Frequencies within WR28-WR284

Waveguide Bands

G.4 Phase Shifters, RF and Microwave 158

61410S Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference; Precision

Connectors; Measured at 30 MHz

61411S Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference; Precision

Connectors; 1-18 GHz, Range 0-360°

61420S Variable Rectangular Waveguide Phase Shifters; Phase Shift Difference at Frequencies WR62,

WR90 Waveguide Bands, Range 0-720°

61450S Special Tests of Phase Shifters, by Prearrangement

G.5 N-Port Scattering Measurements 160

61520S Linear, Reciprocal 2-Port Devices,

10 MHz- 18 GHz

xviii
H. Noise Temperature Measurements 162

62020S Special Noise Temperature Measurements

(Electromagnetic), by Prearrangement

62100S-621 1 IS . . .Noise Temperature of Coaxial Noise

Sources, Type N Precision or 14-mm

Connectors

621 15S-621 16S . . .Special Service for Waveguide Noise Sources

at Frequencies within WR90-WR284 Waveguide

Bands

62120S-62121S . . .Noise Temperature of Rectangular Waveguide

Noise Sources at Specified Frequencies within

WR62 and WR90 Waveguide Bands

62130S-62131S . . .Noise Temperature of WRIO Noise Sources

62132S-62133S . . .Noise Temperature of WR15 Noise Sources

62140S Special Services for Earth Terminals Used in Satellite Communications

I. Electromagnetic Field Strength and Antenna Measurements

1.1 Microwave Antenna Parameter Measurements 165

63100S Gain and Polarization of Standard Antennas

Using Extrapolation Range

63200S Measurement of Pattern, Gain, and Polarization

of Arbitrary Antennas Using Near-Field

Scanning Techniques

63300S Special-Test Service for Calibration of Probes

Used with Near-Field Scanning Techniques

63400S Special Consulting, Advisory, and Other Services

1.2 Field Strength Parameter Measurements 168

64100S Special-Test Service for Antennas/Field Strength

Measurements, Utilizing Transverse Electromagnetic Cell Method

64200S Special-Test Service for Antennas/Field Strength

Measurements, Utilizing the Open-Field

Method

64300S Special-Test Service for Antennas/Field

Strength/Reflectivity Measurements, Utilizing

the Anechoic-Chamber Method

64400S Special-Test Service for Electromagnetic

Interference

J. Pulse Waveform Measurements 170

65100S Impulse Generator Spectrum Amplitude (50 Ohm)

65200S Fast Repetitive Broadband Pulse Parameters

(50 Ohm)

65300S-65301S . . .Network Impulse Response of Coaxial Networks,

10 MHz to 10.0 GHz

65400S Pulse Time Delay through Coaxial Transmission

Lines

xix
Chapter 8—

Time and Frequency Measurements

A. Time and Frequency Dissemination 175 76100S Special Frequency Measurement Service

7611 OS Special Global Time Service

B. Oscillator Characterization 177 77100C Precision Oscillator Frequency Calibration

771 IOC Characterization of Atomic Time and Frequency

Standards

77120C-77131C. . .Characterization of Precision Oscillators: Time and Frequency Domain

77140S Special Time/Frequency Measurements

Alphabetical Cross-index 179

XX

Chapter

A Introduction B Questions and Inquiries

O Fees O Types of Services E Criteria F Reports of Test Results G References to NIST in Advertisements

H Traceability

/ Disclaimer

J Ordering and Scheduling

K Purchase Order

L Shipping, Insurance, and Risk of Loss M Special Instructions for Foreign Customers
Policies

Introduction

The physical measurement services of

the National Institute of Standards

and Technology (formerly the National Bureau of Standards) are designed to help the makers and users of precision instruments achieve the

highest possible levels of measure- ment quality and productivity. The

hundreds of individual services you

will find listed and described in this Users Guide constitute the highest or- der calibration services available in the United States. They directly link a customer's precision equipment or

transfer standards to national measurement standards. These services are offered to public and private or- ganizations and individuals alike.

Questions and Inquiries

This Users Guide is designed to make

the task of selecting and ordering an

appropriate calibration service as quick and easy as possible. Nevertheless, questions will arise. When they

do, we urge you to call or write for immediate clarification. Address general questions and lengthy inquiries

to:Joe D. Simmons

Office of Physical Measurement

Services

National Institute of Standards

and Technology

Physics Building B362

Gaithersburg, MD 20899-0001

(301) 975-2002.

If you have a technical question

concerning a specific service, contact

directly one of the NIST staff members responsible for that calibration

area. Consult the section of this guide

that describes the service in question

for names and addresses.

Fees

NIST recovers the cost of providing

calibration services by charging a fee for each calibration performed. These

fees range from a low of less than

$100 for calibration of a laboratory

thermometer to $50,000 or more for special tests of large microwave an- tenna systems.

PLEASE NOTE: The costs of ser- vices are not stated in this Users

Guide. Instead, they are listed in a separate Fee Schedule, which is up- dated as required to reflect changes

in prices and services. Request a free copy of the current Fee Schedule by

writing or calling the Office of Physical Measurement Services (see sec- tion B).

Types of Services

You will find three types of physical

measurement services described in this guide: Calibration Services, Special Tests, and Measurement Assur- ance Programs.

Calibrations and Special Tests generally designate those NIST services

that check, adjust, or characterize

particular instruments, devices, and

sets of standards on a one-time-perrequest basis. The customer, in most

cases, ships an item requiring calibra- tion to the appropriate NIST laboratory in Gaithersburg, Maryland, or

Boulder, Colorado, as noted in this Users Guide and in the separate Fee

Schedule. The calibrated item is shipped back to the customer, fol- lowed, under separate cover, by a re- port of test procedures and results. Measurement Assurance Programs,

or MAPs, are quality control pro- grams for calibrating a customer's entire measurement system. In a typical

MAP, a stable artifact or set of arti- facts—called transfer standards—are

first measured by NIST and sent to

11

1
a customer's laboratory for a series of

measurements. The transfer standards

are then returned to NIST for remeasurement, along with the participating laboratory's results. NIST reports

its comparative findings to the cus- tomer and, when necessary, offers guidance on how to achieve and

maintain measurement quality.

Successful use of an NIST MAP

requires that the customer make periodic measurements of in-house check

standards to estimate the random er- ror and to ensure that the measure- ment process remains in a state of

statistical control. Unless a laboratory

has a measurement quality control

program to monitor continuously its own measurement process parameters, there is little point in participating in a MAP.

PLEASE NOTE: NIST does not

audit, regulate, or accredit metrology

laboratories as part of the MAP ser- vices. Whatever steps a participating

laboratory may take to improve its measurement process are undertaken

voluntarily.

Criteria

All the measurement services described in this guide meet rigorous

criteria for quality assurance. Calibration Services and MAPs satisfy the

most demanding and explicit requirements in that these services are carried out regularly under pre- established and well-defined conditions; the measurement processes in- volved are well-characterized, stable,

and statistically controlled; and quality-control procedures are well- defined and strictly followed. Furthermore, each Calibration Service or MAP is planned and documented to permit continuity of service over

time. A Special Test is so designated

for one or more of the following rea- sons: 1) the specific type of calibra- tion is seldom requested, thus pre- cluding the mainte-nance of a large

statistical base for controlling the

measurement process,

2) the test requested is unique, or

3) the service is still under development—meaning the measurement or

calibration methods are still being

perfected or all the quality-control

documentation has yet to be completed.

Reports of Test Results

Reports on calibrations or other ser- vices are regarded as the property of

the customer. Copies are not supplied

to other parties except as required by

federal law or requested in writing by

the customer. The results of calibra- tions and tests performed by NIST

apply only to a particular instrument

or standard at the time of test unless

otherwise clearly stated.

References to NIST in

Advertisements

NIST test results or reports shall not be used to indicate or imply that the

National Institute of Standards and

Technology approves, recommends,

or endorses the manufacturer, supplier, or user of any instruments or

standards or that NIST in any way

guarantees or predicts the future per- formance of items after calibration or

test. No reference shall be made to NIST or to reports or results fur- nished by NIST in any advertising or

sales promotions which would indi- cate or imply that NIST approves,

recommends, or endorses any proprietary product or proprietary material.

Jm^ Traceability

Traceability is a term often used to designate a relationship between field measurements or instruments and

NIST measurements or national stan- dards. NIST does not define nor en- force traceability. Moreover, NIST is not legally required to comply with

traceability requirements of other federal agencies; nor do we determine

2
what must be done to comply with

another party's contract or regulation

calling for such traceability. However, NIST can and does provide

technical advice on how to make

measurements consistent with national standards.

Disclaimer

Commercial products—materials and

instruments—are identified in this document for the sole purpose of adequately describing experimental or

test procedures. In no event does

such identification imply recommendation or endorsement by the

National Institute of Standards and

Technology of a particular product; nor does it imply that a named material or instrument is necessarily the

best available for the purpose it serves.

Ordering and Scheduling

Services are best arranged in ad- vance, beginning with a call or letter from the customer to an NIST staff member directly responsible for the

desired service. See the appropriate

technical section of this Users Guide

or the separate Fee Schedule to determine whom to call or write. This

advance communication can clear up

any questions you may have, clarify

the policies and procedures briefly

described here, and permit you to

tentatively schedule a calibration

date. Following the initial communication, you will immediately need to

fill out and send in a purchase

order and prepare and ship the item

according to the procedures described below. If a calibration must

be scheduled far in advance, you may

arrange to delay shipment of the item

until shortly before the scheduled

date; you must, however, submit the

purchase order—complete with the name and number of the desired ser- vice—before a firm calibration date can be assigned. When NIST receives

your valid purchase order and assigns

a firm service date, you will be noti- fied by mail to confirm the order. PLEASE NOTE: Normal

turnaround time for NIST calibration

services varies greatly—from one week to three months—depending on

the type of service requested and

fluctuations in workload. Please contact and schedule in advance to avoid

unnecessary delays.

Purchase Order

Send a purchase order to the address

listed in the appropriate technical sec- tion of this Users Guide, or in the

separate Fee Schedule, before you

ship an item for calibration. The pur- chase order must:

1) State both the name and number of the NIST service being

requested. FAILURE TO IN- CLUDE THE ORDER NUMBER WILL SERIOUSLY

IMPEDE SCHEDULING

AND SERVICE.

2) Clearly identify the item(s) being sent for calibration, including any serial number.

3) Give the name, address, and

telephone number of the re- questing company's procurement officer. 4) Give the name, address, and

telephone number of the re- questing company's technical

contact, if different from

above.

5) List separately the instructions

for return shipment, insurance,

mailing of the test report, and

billing. (Federal or state agency requests for calibration

services should be accompanied by a document authorizing that the cost of the service

be billed to the agency.)

6) Clearly state any special or

necessary conditions of test

such as operating frequency or temperature.

PLEASE NOTE: Receipt of orders

by NIST does not imply acceptance

3
of any provisions set forth in the

order that are contrary to the policy,

practice, or regulations of the

National Institute of Standards and

Technology or the U.S. government.

In general, NIST will not sign any

affidavits, acknowledgment forms, or

other documents that may be re- quired by company policy governing the procurement of goods and

services.

m Shipping, Insurance, and

^mm Risk of Loss

Ship an instrument or standard to the

address to which you mailed your

purchase order. Adhere rigorously to the following procedures:

1) Ship only items in gr od repair.

Apparatus in disrepair will not be calibrated. If defects are found after calibration has

begun, the procedure will be

terminated, a report issued, and

a charge levied for work

completed.

2) Use strong, reusable packing

materials and containers

marked clearly and indelibly on the outside with the

requestor's name, address, and

the following notation:

REUSABLE CONTAINER,

DO NOT DESTROY.

3) Follow any special shipping

procedures given in the technical sections of this guide,

particularly those sections covering radiation and dosimetry

measurements.

4) Insure the shipments to and

from NIST and clearly state the method of return shipment.

NIST will not assume liability for loss or damage unless such

loss and damage result solely

from the negligence of NIST

personnel. If return shipment

by parcel post is requested or

is suitable, NIST will prepay

the return shipment but will not insure it. When no shipping or insurance instructions are

furnished, NIST will return the

shipment by common carrier, collect and uninsured.

PLEASE NOTE: Fees for NIST services do not include

shipping costs. M Special Instructions for

r Foreign Customers

The National Institute of Standards

and Technology is authorized to provide measurement services, in- cluding calibrations, for organizations or individuals located outside the

United States. NIST policy requires a thorough review of each request to determine if a comparable service is available in the requestor's country.

Foreign customers must, therefore,

provide the following information

to the Office of Physical Measurement Services (see address under

Section B):

1) If a national or official stan- dards laboratory in the country

of the requesting organization

is available and provides identi- cal or similar service to that re- quested from NIST, state why

NIST should provide the ser- vice.

2) Provide a detailed description

of the instrument or standard

to be tested, particularly if it is not manufactured in the United

States.

3) Provide a detailed description

of the measurements that are needed or indicate the test or- der number as given in this Users Guide or in the separate

Fee Schedule.

4) Provide a description of any

special requirements that might

affect the decision to provide

the service. For example, will there be a need for special adjustments, or will the length of

time in which the device is available for measurement be

restricted?

If the request for the measurement

service is accepted by NIST, the re- questing organization will be notified

4
of the cost of service and will be

given the identification of the NIST

laboratory that will perform the measurements. The requesting organization must then complete the

following steps:

1) Contact the NIST technical

unit that will provide the ser- vice to determine the schedule.

2) Send a purchase order to the

Office of Physical Measurement Services. Complete

addresses should be provided

for returning the instrument

and for mailing the calibration or test report. Send a check

payable in U.S. dollars to the

Office of Physical Measurement

Services for the full cost of the

service. The check must be

drawn on a U.S. bank. NIST

cannot begin the service until

full payment has been received.

3) Ship the instrument or stan- dard to the appropriate NIST

technical unit. Air freight is

most satisfactory. You must

prearrange shipment with a customs broker for entry of the

instrument into the United

States with prepaid transportation from the port of entry.

Entry bond is required for instruments not manufactured

in the United States. If arrangements are made with a broker in the country of origin, that broker should, in turn, have a U.S. customs broker in or near the port of entry who

will arrange for the entry of

the instrument and its trans- portation to NIST. Direct ar- rangements can be made with

customs brokers located in the

Washington, DC/Baltimore,

Maryland, metropolitan area or

in the Denver, Colorado, area, as appropriate. These brokers can also arrange for transportation to the port of exit after NIST has completed the tests.

Members of the Measurement Services staff, clockwise from upper left: Armatfia Osborne, calitxation assistant; Verna Moore, secretary; Donna Fredericks, computer programmer analyst; Joanne Marstiall, computer assistant; Treva Siedling, administrative officer; Joe Simmons, acting chief. Office of Physical Measurement Services; Ernest

Garner, special assistant. Not shown: Margaret Musick, secretary; and Katlry Hillen, calibration assistant for NIST Boulder Laboratories.

5
Chapter

A Length Measurements B Diameter Measurements C Complex Dimensional Standards O Optical Reference Planes &

Roundness Standards E Angular Measurements F Surface Texture G Hydrometers

H Volume and Density
Dimensional Measurements 10()10C-10060S

Length Measurements

Technical Contacts:

Grace Chaconas William B. Penzes Ronald G. Theodore D. 10010C-10050S 10020C HarUock Doiron

Tel: 301/975-3468 Tel: 301/975-3477 10030C-10040C 10060S

Tel: 301/975-3465 Tel: 301/975-3468

Mailing Address: A107 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items lOOlOC Gage Blocks

10020C Line Standards

1(X)30C Surveying and Oil Gaging Tapes

10040S Special Tests of Surveying Leveling Rods

10050S Special Tests of Length Standards

1(X)60S Special Tests of Sieves

Gage Blocks (lOOlOC)

This calibration service provides for measurement of the length of gage

blocks by either comparison to NIST

master gage blocks or by direct inter- ferometry. Generally, the length is transferred from known master blocks

by a systematic intercomparison pro- cedure using mechanical comparators.

Comparators with laser scales are also

available. All gage blocks submitted for test should be in substantially new block

condition, and each block should be

marked with an identification number.

In shipping gage blocks, extreme care should be taken against both corrosion and damage by contact with

other gage blocks. All defining steel surfaces should be greased and blocks

padded with waxed paper or volatile rust inhibitor treated paper. A

greased steel surface coming in contact with newspaper, wrapping paper

(unwaxed), or excelsior is likely to

corrode. Sets of gage blocks should

have packing inside the case and the case should be bound shut, as the

clasps frequently open or break during shipment.

Square or rectangular blocks or

lengths up to 20 inches are routinely

calibrated and the lengths reported in English or metric units. For blocks

longer than 20 inches, the NIST technical contact should be consulted in advance to discuss alternative measurement techniques, approximate

costs, and scheduling.

The measurement uncertainty re- ported is the sum of the random error

in the measurement of the block un- der test and the estimated systematic

error in the measurement process. The process used to estimate this sys- tematic error is documented in publications referenced in this catalog. Although the uncertainty varies slightly

with each measurement, the variation

is usually small. A reasonable estimate

for the accuracy of the calibration is 2 microinches (0.05 micrometer) for blocks under 2 inches, and with accu- racy decreasing with length to 20 microinches for the 20-inch blocks.

Line Standards (10020C)

Line standards of 1 meter or less are measured on an instrument called a

line scale interferometer, which is used to measure the distance between

suitable lines on a flat surface. The in- strument employs a fixed photoelectric microscope to determine the

position of the scale lines, a linearly

mobile carriage in the focal plane of

the microscope to carry the scales, a

calibrated laser interferometer to measure carriage displacement, and a temperature-controlled housing en- closing the whole apparatus.

The system is now highly auto- mated using a laboratory microcomputer, NIST-developed optical

processing, and servo electronics. With the microscope focused on the

scale zero line, a servo moves the

7
10010C-10060S

carriage until a null signal indicates

the line is centered in the microscopic field. A stepping motor then

drives the carriage until the next line on the scale is reached. Servoed line centering again takes place. The car- riage is now moved precisely the dis- tance between scale lines, and the

interferometer has now measured this distance in laser light wavelengths.

Proceeding down the scale in this manner results in the measurement of

the line spacings.

The maximum length of line stan- dards that can be measured is 1 meter, and the maximum width of any

part of the piece being calibrated can- not exceed 150 millimeters. The accu- racy of the calibration depends significantly on the shape and optical

properties of the line, the bickground, and the geometric flatness of

the artifact being calibrated. If the

lines have straight edges and are 2 to 10 micrometers wide, if there is good

contrast between the line and the

background, and if the reference sur- face of the artifact is flat, then the ac- curacy of the calibration will be near optimum. Uncertainties as low as 0.006 micrometer have been achieved on short intervals, and on 1 -meter

lengths uncertainties of 0. 1 micrometer can be achieved. The current

overall system accuracy is limited by

imprecise knowledge of the refractive

index of air.

Surveying and Oil Gaging Tapes

(10030C)

The calibration of surveying tapes

and oil gaging tapes is carried out in a laboratory that houses two permanent working standards, a laser inter- ferometer, and a 50-meter (200-foot)

stainless steel bench. For the most

part measurements are performed us- ing a laser system that is referenced

against a cube-corner retroreflector attached to a microscope, which is used manually for line location. The

laboratory is maintained at 20 °C, but

a control system can vary the chamber temperature from 15 to 40 °C for special tests. Calibration of tapes will

normally be made with the tape

under tension and supported on a

horizontal-flat surface. Unless otherwise requested, the total length and

each 15-meter or 50-foot subinterval

will be measured and reported. Each

interval calibrated on a surveying

tape will have computed lengths for two (single catenary), three, four, and

five equidistant points of support.

The laser standard is capable of

calibrating tapes with scribed graduations to an accuracy of 2 parts per

million (ppm). Calibrations made with

respect to the stainless steel tape

bench are normally reported to an accuracy of 10 ppm. An NIST serial number will be engraved on each cal- ibrated tape for identification. Figure 1 summarizes the accuracy

of length measurements at NIST. In- cluded are the NIST 5-meter bar,

gage block calibrations, end line stan- dards, and geodetic/steel tapes.

Figure 1. Accuracy of Length Measurements at NIST

10"

10'

10*^

10'

10^

10"

10^

10^

Laser

Interferometric Comparison,

Krypton 86 Wavelength

Gage Block

Calibration End

Standards

5 Meter

Bar

Steel Tapes

Line Standards

10"''10"'10"''10"'^10"''10""10"^10~M0° 10' 10^ 10" 10'

Length, inch

I I I I I I I

I I I I i_ 10"''10"''10"M0''^10"'10~'10""10"'10^M0° 10' 10^

Length, meter

8
10010C-10060S

Special Tests of Surveying Leveling

Rods (10040S)

Leveling rods are currently calibrated

using two methods. One method

involves the comparison of the rod to a 3-meter standard at the 1-, 2-, and

3-meter intervals. A second system

provides measurement at multiple

intervals and automatic report generation. This automated system incorporates a 7-meter one-dimensional

measuring machine, a motorized

carriage, a photoelectric microscope,

and a helium-neon laser interferometer interfaced to a minicomputer.

Measurements can be made on

virtually any type of linear scale or

leveling rod with scribed, engraved,

or painted graduations. The random

error of measuring high-quality level- ing rods is plus or minus 6 micrometers for new rods and plus or minus

12 micrometers for used rods at the one standard deviation level. The sys- tematic errors are largely unevaluated, and to account for their exis- tence the total error being reported

by NIST at present is plus or minus

50 micrometers for new rods. The

length of intervals will be reported as measured at 20 °C unless otherwise

requested. The report can be supplied

in either written or computer-readable form.

Special Tests of Length Standards

(10050S)

Measurements on end standards with

spherical ends, gage blocks of unusual

shape or exotic materials, or measure- ment of standards between 24 and

240 inches can sometimes be done,

but agreement with the technical contact should be made before sending

material.

Special Tests of Sieves (10060S)

To determine conformity to ASTM

Ell specifications.

References—Length Measurements

Grid Plate Calibration at the

National Bureau of Standards,

T. D. Doiron, J. Res. Natl. Bur. Stand. (U.S.), 93, No. 1 (Jan.-Feb.

1988).

Interferometric Measurement of

Length Scales at the National Bureau of Standards, J. S. Beers and

K. B. Lee, Prec. Eng., 4, No. 4, 205 (Oct. 1982).

Contact Deformation of Gage Block

Comparisons, J. S. Beers and J. E. Taylor, Natl. Bur. Stand. (U.S.),

Tech. Note 962 (May 1978).

Intercomparison Procedures for Gage

Blocks Using Electromechanical

Comparators, J. S. Beers and C. D.

Tucker, Natl. Bur. Stand. (U.S.),

NBSIR 76-979 (Jan. 1976).

A Gage Block Measurement Process Using Single Wavelength Interfer- ometry, J. S. Beers, Natl. Bur.

Stand. (U.S.), Monogr. 152 (Dec.

1975).

Preparations for Gage Block Comparison Measurements, C. D.

Tucker, Natl. Bur. Stand. (U.S.),

NBSIR 74-523 (July 1974).

Gage Block Flatness and Parallelism

Measurement, J. S. Beers and

C. D. Tucker, Natl. Bur. Stand.

(U.S.), NBSIR 73-239 (Aug. 1973).

An Automatic Fringe Counting Inter- ferometer for Use in the Calibration of Line Scales, H. D. Cook

and L. A. Marzetta, J. Res. Natl. Bur. Stand. (U.S.), 65C, 129 (1961).

9
11010S-11080S

Diameter Measurements

Technical Contacts:

William H. David Stieren Theodore D.

Gallagher, Jr. 11020C, 11080S Doiron

IIOIOS, 11030S, Tel: 301/975-3468 11050S-11070S 11040S Tel: 301/975-3468

Tel: 301/975-3468

Mailing Address: A107 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items IIOIOS Special Tests for Plug Gages: External Diameter

Standards 11020C Measuring Wires for Threads and Gears

11030S Special Tests of Spherical Diameter Standards: Balls 11040S Special Tests of Internal Diameter Standards: Ring

Gages

11050S Special Tests of Length and Diameter

11060S Special Tests of End Standards

1 1070S Special Tests of Step Gages

11080S Special Tests of Thread Measuring Wires

General Information

For controlling dimensions in the

manufacture of all products, various

types of dimensional gages are used. The variety of such gages measured

includes cylindrical plug gages, ring gages, balls for diameter, and screw

thread gages. The diameter standards

and gages, with the exception of

thread and gear measuring wires, are generally intended to be used as comparison masters.

Special Tests for Plug Gages: External

Diameter Standards (IIOIOS)

NIST will provide calibrations of external diameter standards by special

arrangement. Please consult with the

technical contact listed above.

j Measuring Wires for Threads and

Gears (11020C)

This service provides for measure- ment of the diameter of thread and

gear measuring wires by intercomparison to NIST Master wires. The

diameter is transferred from known

Master wires using a systematized in- tercomparison sequence with a mechanical comparator.

All measuring wires submitted for

test should be in substantially new

condition, each wire should be appropriately bottled, and the bottle should

be labeled with an identification number. In shipping thread wires, ex- treme care should be taken to prevent

corrosion; all wires should be properly greased and their bottles rigidly

contained inside an appropriate packing case. Thread measuring wires for 60- degree and 29-degree threads are

tested for compliance with the latest specifications in commercial use. These wires are calibrated, and the

pitch diameter is computed. Gear

measuring wires in the 1.92"/P,

1.728"/P, 1.68"/P, and 1.44"/P series are tested for compliance with the

latest specifications in commercial use and the mean diameter reported.

Accuracies are reported to a 3-sigma

confidence level of 10 microinches

for English wires and 0.25 micrometer for metric wires.

Special Tests of Spherical Diameter

Standards: Balls (11030S)

Balls used in precision bearings and

master balls used as transfer diameter

standards are calibrated according to current commercial practice. The ball diameters reported are the undeformed sizes as calculated with the

Hertz relations to maintain a consistency in reported sizes.

Special Tests of Internal Diameter

Standards: Ring Gages (11040S)

NIST will provide calibrations of

ring gages by special arrangement.

10
11010S-11080S

Please consult with the technical contact listed.

Special Tests of Length and Diameter

(11050S)

NIST has a wide variety of state-of- the-art metrology equipment and can

provide services associated with

dimensional quality control as special

tests. A three-dimensional measuring

machine is available for calibration of

two- and three-dimensional ball

plates, two-dimensional grid plates,

and other artifacts of complex shape.

The machine has a working volume

of 48 X 24 X 12 inches and can detect

a length difference of 0.013 micrometer. Reference to the international

standard of length is through interfer- ometers. Uncertainties in the calibra- tions are variable. Spherical diameter

standards, such as balls used in precision bearings and master balls used as transfer diameter standards, are cali- brated using a laser-based mechanical

comparator.

Special Tests of End Standards

(11060S)

Standards up to 20 feet in length,

having spherical, flat, or pointed ends can be measured; lengths are reported

with 2.5 lb. measuring force unless otherwise requested.

Special Tests of Step Gages (11070S)

Step gages having flat parallel faces can be measured in lengths up to

1 meter.

Special Tests of Thread Measuring

Wires (11080S)

Wires for unusual thread sizes and for threads finer than 80 tpi are measured

in a manner consistent with current commercial practice.

References—Diameter Measurements

Federal Standard H-28, Screw

Thread Standards for Federal

Services. English and metric versions. These handbooks are avail- able from the General Services

Administration (GSA).

American National Standard B1.2,

Amer. Natl. Stand. Inst., New

York.

Designs for the Calibration of Small

Groups of Standards in the Pres- ence of Instrumental Drift, J. M.

Cameron and G. E. Hieles, Natl. Bur. Stand. (U.S.), Tech. Note 844

(Aug. 1974).

On the Measurement of Thread

Measuring Wires, B. N. Norden,

Natl. Bur. Stand. (U.S.), Report

10987 (Jan. 1973).

Measurements of Cylindrical Standards, R.C. Veale, Natl. Bur.

Stand. (U.S.), NBSIR 73-136

(1973).

On the Comparison of Cylinder in Contact with a Plane Surface, B. Norden, Natl. Bur. Stand. (U.S.),

NBSIR 73-243 (1973).

11
12010C-12070S

Complex Dimensional Standards

Technical Contacts:

Edgar G. Erber Brian Scace Theodore D. 12010C-12060S 12010C-12060S Doiron

Tel: 301/975-3468 Tel: 301/975-3468 12070S

Tel: 301/975-3468

Mailing Address: A107 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

120 IOC API Threaded Plug and Ring Gages

12020S Special Tests of Plain Conical Plug and Ring Gages

12030S Special Tests of Threaded Plug and Ring Gages

12040S Special Tests of Calipers and Gages

12050S Special Tests of Micrometer Screws and Dial

Micrometers

12060S Special Tests of Penetration Needles

12070S Special Tests of Two-Dimensional Gages

API Threaded Plug and Ring Gages

(12010C)

NIST provides calibration and certifi- cation services for API threaded plug

and ring gages, casing, tubing and

line pipe plug and ring gages as well

as sucker rod gages. NIST is the

custodian of the American Petroleum

Institute (API) Grand Master rotary

thread gages. These Grand Master

gages are maintained and have been

recalibrated at NIST for more than

40 years. They can be considered an

international standard since all API

Regional Master Gages throughout

the world are referenced to NIST.

Foreign product manufacturers can have their Reference Master Gages

calibrated and certified by NIST or by one of the other national standard

laboratories listed below:

National Physical Laboratory,

Teddington, England

National Research Laboratory of

Metrology, Tokyo, Japan

National Standards Laboratory,

Chippendale, N.S.W., Australia

Physikalisch Technische Bundesanstalt, Braunschweig, Germany

Laboratoire National d'Essais,

Paris, France

Instituto Nacional de Technologia

Industrial, San Martin, Argentina

As required, the API lab is temperature controlled at 20 °C. Parameters

measured for plug gages are length of

plug, taper, pitch diameter, major di- ameter, thread lead, lead and following thread half-angles, depth of

thread, pitch line width, and radius of

curvature. Parameters measured for ring gages

are length of ring, taper, thread lead,

minor diameter, lead and following

thread half-angles, counter bore,

depth of thread, pitch line width, ra- dius of curvature, and standoff. These calibrations are based on a

three standard deviation confidence

level and are accurate to plus or mi- nus 0.0003 inch.

All gages received must be marked

with the API monogram and the API

registration number. If not so marked

the gages will be returned to the cus- tomer uncalibrated. Gages which

meet the specifications will be

marked as specified in the API Standards. All thread gages must be submitted in sets of plug and ring. The

name of the gage owner should be

given for inclusion in the Report of

Calibration.

Special Tests of Plain Conical Plug

and Ring Gages (12020S)

NIST will provide special tests of

plain conical plug and ring gages by

special arrangement. Please consult

the technical contact listed.

Special Tests of Threaded Plug and

Ring Gages (12030S)

NIST will provide special tests of

threaded plug and ring gages. Please

consult the technical contact listed.

12
Special Tests of Calipers and Gages

(12040S)

Vernier calipers and similar gages can be accepted for test.

Special Tests of Micrometer Screws

and Dial Micrometers (12050S)

Standard procedures using gage

blocks for calibration of micrometers

are available in many standard documents such as U.S. Standard GGGC-1056. If necessary, however, NIST

can provide special tests on micrometer screws and dial micrometers on

request.

Special Tests of Penetration Needles

(12060S)

Needles and cones are tested for compliance with ASTM specifications. All devices must have individual identification numbers.

Special Tests of Two-Dimensional

Gages (12070S)

NIST can provide special tests of

two-dimensional gages, ball plates, or

grid plates, with dimensions up to 24

inches by 24 inches. The accuracy of

such calibrations depends substantially on the quality of the gage, but

accuracies of 1 micrometer or better are obtainable.

References—Complex Dimensional

Standards

On Characterizing Measuring Machine Geometry, R. J. Hocken and

B. R. Borchardt, Natl. Bur. Stand.

(U.S.), NBSIR 79-1752 (1979).

Three-Dimensional Metrology, R. J. Hocken et al.. Annals of the CIRP,

26-1 (1977).

Unified Three-Dimensional

Program—Two Useful NonContacting Probes, J. A. Simpson,

Natl. Bur. Stand. (U.S.), Report

10597 (1971).

13
13010S-13030S

y W Optical Reference Planes &

m Roundness Standards

Technical Contacts:

Jay H. William H. Zimmerman Gallagher, Jr. 13010S 13020S and 13030S

Tel: 301/975-3468 Tel: 301/975-3468

Mailing Address: A 107 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

1301 OS Special Tests of Optical Reference Planes (Flats) 13020S Special Tests of Roundness

13030S Special Tests of Roundness Calibration Specimens

Special Tests of Optical Reference

Planes (13010S)

Optical reference planes are tested in- terferometrically, horizontally sup- ported with the test surface

supported on three equally spaced

pads located at 0.7 of the radius from

the center. The measurement is per- formed along two marked diameters

at 90° to each other on each surface

when each diameter is parallel to two

of the support pads.

Roundness Calibration Specimens and

Measurements. Special Tests of

Roundness (13020S and 13030S)

The deviation from roundness at eight or more positions around nominally round standards is determined.

The size of the calibration step or deviation from roundness on calibration

standards is determined. The departure from roundness of components

and gages is measured, and the results are reported in graphical form.

NIST will provide special tests of

roundness calibration specimens by

request. Please consult with the technical contact listed.

Jay H. Zimmerman measures a ball using a roundness

measuring instrument.

References—Optical Reference Planes

The Calibration of an Optical Flat by

Interferometric Comparison to a Master Optical Flat, C. P. Reeve,

Natl. Bur. Stand. (U.S.),

NBSIR 75-975 (Dec. 1975).

A Survey of the Stability of Optical

Flats, C. P. Reeve and R. C. Veale.

Natl. Bur. Stand. (U.S.), NBSIR

73-232 (June 1973).

14
14010C-14060S

ma

Angular Measurements

Technical Contact:

William H.

Gallagher, Jr. Tel: 301/975-3468

Mailing Address: A107 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 14010C Angle Gage Blocks

14020S Special Tests of Optical Polygons

14030S Special Tests of Rotary and Indexing Tables

14040S Special Tests of Wedges

14050S Special Tests of Autocollimators

14060S Special Tests of Angle Generators

Angle Gage Blocks (14010C)

This service provides for the measurement of the angle of angle gage

blocks by direct comparison to NIST

master angle blocks using a dual- autocollimator system. Current auto- collimators have resolution to 0.01 arc-second and electronic readout.

The blocks are enclosed in a special

chamber during intercomparison to minimize air currents, and the laboratory is maintained at 20 °C to within

plus or minus 0.1 degree.

All angle gage blocks submitted for

test should be in substantially new

block condition, and each block

should be marked with an identifica- tion number. In shipping angle blocks

the same care as is exercised in gage

block shipment should be used, as the

surfaces are subject to corrosion.

All standard sizes of angle blocks can be calibrated in the NIST facilities. Blocks with angles ranging from

1 arc-second to 45 degrees are routinely handled; however, optical squares and other standards can also be accommodated. Accuracy at the

3-sigma level is approximately 0.

arc-second; this value, however,

varies with the condition of the gaging surface on the standard.

Special Tests of Optical Polygons

(14020S)

The calibration of polygons is done

with autocoUimation techniques. It consists of the determination of flat- ness of each face, variation of the an- gle between each face and the base

(where possible the polygon will be

adjusted for minimum variation), and

the angle between faces. Figure 2 summarizes the precision of angle cal- ibration for master angle gage blocks

and polygons.

Figure 2. Precision of Angle Calibrations for Master

Angle Gage Blocks and Polygons

10'

10^

10"

10^

10^

10

1

Angular Measurement by

Direct Interferometry Angle Gage Blocks by

Angular Subdivision ^

Polygons by Complete c, ^^-^'^l

Circular Closure ,C-'<f' -" '-'^ ^

72

' 20°

c 12 10^,654

15° °45° 5" -

'3 24

1 2 3 5 10 20 50100

* Based on 3 standard

deviations. Systematic

errors may be ot ttie same order ot magni- tude as ttie precision

ot determination.

n 1 1

1

I I I I I 2 5 20 50 2 5 10 20 50

Seconds Minutes

15
14010C-14060S

Special Tests of Rotary and Indexing

Tables (14030S) Instruments and tools used for the

precise measurement of angle, such as precision angular rotary and indexing

tables, autocoUimating telescopes, or

angle generating equipment, are cali- brated at specific angular settings.

Special Tests of Wedges (14040S)

Solid angle calipers and step mirrors

are calibrated by autocollimation or

interferometric techniques as to the

angle between faces. Wedges are cali- brated by autocoUimating or interfer- ometric techniques at a specified

wavelength for deviation angle. Mechanical angular references such as cylindrical squares and machinist's squares are usually calibrated by mechanical techniques.

Special Tests of Autocollimators

(14050S)

Special tests of autocoUimating tele- scopes may be made by special arrangement. Please consult the

technical contact listed.

Special Tests of Angle Generators

(14060S)

Precision equipment, including trans- ducers, are measured at specific angular settings.

References—Angular Measurements

The Calibration of Angle Blocks by

Intercomparison, C. P. Reeve,

Natl. Bur. Stand. (U.S.), NBSIR

80-1967 (1980).

The Calibration of Indexing Tables

by Subdivision, C. P. Reeve, Natl. Bur. Stand. (U.S.), NBSIR 75-750

(July 1975).

A Survey of the Temporal Stability

of Angle Blocks, R. C. Veale and

C. P. Reeve, Natl. Bur. Stand.

(U.S.), NBSIR 74-601 (Nov. 1974).

David Stieren measures angle blocks by comparing test blocks to NIST Master

blocks using two autocollimators.

16
Surface Texture

Technical Contacts:

Arie Hartman Cynthia K. Rymes

Tel: 301/975-3475 Tel: 301/975-4081

Mailing Address: A 117 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 15010C Roughness Calibration Specimens

15020C Surface Roughness Comparison Specimens

15030C Step Height Measurements

Roughness (15010C-15030C)

NIST provides measurement services

in three categories: instrument cali- bration specimens (with regular geometric profiles), roughness comparison (and other types of roughness

specimens), and step height speci- mens. The property of surface roughness

in the 10-ju.m range and below

and step heights up to 25 jLtm are measured by means of a minicomputer/stylus instrument system. Using

an interferometrically measured step, the system is calibrated at each value

of magnification employed during a measurement.

In measurements of roughness, sur- face profiles are taken according to American National Standard

B46. 1-1985 using a 0.8-mm cutoff

length and a traversing length of 4

mm. A number of other statistical parameters and functions may be cal- culated from the stored profile data,

including the rms roughness, average

slope, average wavelength, skewness,

amplitude density function, autocorrelation function, and power spectral

density.

In step height measurements, a

straight Hne is fitted by the method of

least squares to each side of the profile of the step and the height is cal- culated from the position of these

two lines. The NIST cahbration uncertainty

for step height or depends on a number of factors, the most important

being the step or R^ value of the stan- dard used. The uncertainties range

from approximately 0.4 jam at a step

height of 25 jam to 0.002 jam at the

smallest step heights. Comparable uncertainties are achieved for measure- ments of Ra.

References—Surface Texture

Characterization of Surface Topography, T. V. Vorburger and G. G.

Hembree, in Methods of Surface

Characterization, Vol. 3 (in press).

Measurements of Roughness of Very

Smooth Surfaces, T. V. Vorburger,

Annals of the CIRP 36, No. 2, 503

(1987).

Direct Comparison of Mechanical

and Optical Measurements of the

Finish of Precision Machined Optical Surfaces, E. L. Church, T. V.

Vorburger, and J. C. Wyant, Optical Engineering 24, 388 (1985).

Sinusoidal Profile Precision Roughness Specimens, E. C. Teague,

F. E. Scire, and T. V. Vorburger,

Wear, 83, 61 (1982).

Three-Dimensional Stylus Profilometry, E. C. Teague, F. E. Scire,

S. M. Baker, and S. W. Jensen,

Wear, 83, 1 (1982).

17
FASTMENU: A set of FORTRAN

Programs for Analyzing Surface

Texture, T. V. Vorburger, Natl. Bur. Stand. (U.S.), NBSIR 83-2703

(July 1982).

Optical Techniques for On-Line Measurement of Surface Topography,

T. V. Vorburger and E. C. Teague,

Prec. Eng., 3, 611 (1981).

Uncertainties in Calibrating a Stylus

Type Surface Texture Measuring

Instrument with an Interferometrically Measured Step, E. C. Teague,

Metrologia, 14, 39 (1979).

Measurements of Stylus Radii, T. V.

Vorburger, E. C. Teague, F. E.

Scire, and F. W. Rasberry, Wear,

57, 39 (1979).

FAST Facility Available for Engineering Needs, T. V. Vorburger,

E. C. Teague, and F. E. Scire,

Dimensions/NBS, 62, 18 (1978).

Evaluation, Revision, and Application of the NBS Stylus/Computer

System for the Measurement of

Surface Roughness, E. C. Teague,

Natl. Bur. Stand. (U.S.), Tech.

Note 902 (Apr. 1976).

Precision Reference Specimens of

Surface Roughness: Some Characteristics of the Cali-Block, R. D.

Young and F. E. Scire, J. Res.

Natl. Bur. Stand. (U.S.), 76C (Eng.

and Instr.), Nos. 1 and 2, 21 (Jan.-

June 1972).

1 8
160 IOC

G.

Hydrometers

Technical Contact:

John F. Houser

Tel: 301/975-5956

Mailing Address: 105 Fluid Mechanics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 16010C Reference Standard Hydrometers

Reference Standard Hydrometers

(16010C)

Specific gravity hydrometers covering the range 0.62 to 3 g/cm' and

proof spirit hydrometers in the range

0 to 200 proof, which are designed

and used as reference standard hydrometers (used to test other hydrometers), normally are accepted for

calibration. A limited number of

other types of reference standard hydrometers will be accepted for multipoint calibration, subject to discussion. Instruments accepted must comply essentially with the requirements

of NBS Circular 555, "Testing of

Hydrometers."

John Houser reads the graduated scale of an alcohol

hydrometer in his calibration chamber.

i

1

19
17010C-17040S

Volume and Density

Technical Contact:

John F. Houser

Tel: 301/975-5956

Mailing Address: 105 Fluid Mechanics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

170 IOC Volume Standards

17020S Special Tests of Volume Standards

17030S Special Tests of Density: Solids 17040S Special Tests of Density: Liquids

Volume Standards (17010C)

The procedure used for testing glass

volumetric apparatus is to weigh the

amount of distilled water contained

or delivered with reference to the

graduations marked on the instru- ment, the volume being computed

from the density of the water. (Refer- ences provided upon request.) The

quality of the markings and the care

exercised in reading or setting the liquid level are major factors in test cal- ibration and usage. NIST does not provide routine calibration services

for glassware; however, NIST will accept factory standards and replacement glassware for the State Weights

and Measures Departments, in the

range of 10 mL to 5 liters, which

conform essentially to requirements

contained in NBS Circular 602,

"Testing of Glass Volumetric Apparatus," Federal Procurement Specifications NNN-B-00789 (Buret,

straight, precision), NNN-F-00289a

(Pipet, volumetric), NNN-P-0035a

(Pipet, measuring), or NNN-F-00289a

(Flask, volumetric), if such instruments are to be used as reference or

transfer standards.

The usual calibration procedure for metal volumetric apparatus consists

of determining the value "to contain"

or "to deliver" by either gravimetric means or by the use of transfer stan- dards. Normally NIST will accept

for calibration instruments that have

values in the range 1 gill to 1500 gal,

which comply essentially with the

specifications contained in NBS

Monograph 62, "Testing of Volumetric Standards," and which are free from dents, rust, or scratches. Although a scale calibration service is provided, NIST does not adjust

scales. The zero index or the gage

scale should, therefore, be adjusted

and scaled prior to calibration. Slicker plate type standards should be

adjusted by the manufacturer.

Special Tests of Volume Standards

(17020S)

Special tests may be made of volume

standards by prearrangement with

NIST.

Special Tests of Density: Solids

(17030S)

NIST does not normally determine

density of solids for customers. However, special arrangements can be

made for customers to use the NIST

solid density measurement equipment

to make their own tests. The technical contact cited in this section

should be consulted concerning special arrangements for use of NIST

equipment.

Special Tests of Density: Liquids

(17040S)

NIST will accept requests for density

determinations of liquids if the need

is critical. Limitations on the mass,

physical, dimensions, or volume of

the sample are available on request.

At NIST, liquid densities usually are determined by gravimetric, or weighing methods. Other methods are

available depending on the require- ments.

20
17010C-17040S

References—Volume and Density

Measurements

Reevaluation of the Densities of the

Four NBS SiHcon Crystal Standards, H. A. Bowman, R. M.

Schoonover, and C. L. Carroll,

Natl. Bur. Stand. (U.S.), NBSIR

75-768 (Aug. 1975).

The Utilization of Solid Objects as Reference Standards in Density

Measurements, H. A. Bowman,

R. M. Schoonover, and C. L.

Carroll, Metrologia 10, 117 (1974).

Calibration of Small Volumetric Laboratory Glassware, J. Lembeck,

Natl. Bur. Stand. (U.S.), NBSIR

74-461 (Oct. 1974).

The Equivalence of Gravimetric and

Volumetric Test Measure Calibration, R. M. Schoonover, Natl. Bur. Stand. (U.S.), NBSIR 74-454 (Feb.

1974).

A Density Scale Based on Solid Objects, H. A. Bowman, R. M.

Schoonover, and C. L. Carroll,

J. Res. Natl. Bur. Stand. (U.S.),

78A, No. 1, 13 (Jan.-Feb. 1974).

Procedures for the Calibration of

Volumetric Test Measures, J. F. Houser, Natl. Bur. Stand. (U.S.),

NBSIR 73-287 (Aug. 1973).

21
Chapter

A Flow Rate Measurements B Flow Measurements at Cryogenic

Temperature

C Airspeed Measurements D Mass Standards E Force Measurements F Vibration Measurements G Acoustic Measurements H Ultrasonic Reference Block Measurements

/ Ultrasonic Transducer Measurements J Acoustic Emission Transducer Measurements
Mechanical Measurements 18010C-18050S

Flow Rate Measurements

Technical Contacts:

Kenneth R. George E. Benson Mattingly

Tel: 301/975-5945 Tel: 301/975-5939

Mailing Address: 105 Fluid Mechanics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 18010C Single Turbine Meters 18020C Tandem Turbine Meters

18030C Flow Rate Meters (Direct Reading in Flow Rate Units)

18040C Head Class Flow Measurement Devices

18050S Special Tests for Liquid and Gas Flow Rates

Flowmeters (18010C-18040C)

NIST provides calibration services

for liquid flowmeter systems that in- clude a flowmeter and pertinent adja- cent tubing, auxiliary measurement

instrumentation, and readout equip- ment. Flowmeter systems having demonstrated precision and temporal stabil- ity commensurate with the quality of

the calibrations are accepted for cali- bration. Calibration tests usually in- clude five different flow rates, although additional rates can be in- cluded on request. At each flow rate, five determinations of meter indication and flow rate are made; the entire test sequence is repeated—usually on the following day.

Meter systems submitted should

have conventional connections, either

A/N flare fittings up to 2-in (5 cm)

nominal diameters, or National Pipe

Thread fittings up to 3-in (7.6 cm)

nominal diameter. Larger meters must terminate with ASA 150-lb steel flanges, or grooved-end steel pipe

compatible with Victaulic couplings

(for water meters), or with adapters

thereto: For air flow systems with

flow rates above 100 ftVmin, flanges

must terminate with ASA 300-lb steel flanges except for laminar element

flowmeters operated near ambient

pressure levels. Connections other

than these should not be submitted

unless special arrangements have

been made in advance.

NIST maintains a range of facilities that are capable of serving as national

standards for fluid flow rate measure- ments for a wide range of fluid and

flow conditions.

Small Air Flow Facilities: Calibration

of devices in this laboratory covers

the air flow range up to approximately 100 standard cubic feet per

minute (SCFM). The mass flow rate of gas passing through a metering

device during its calibration is deter- mined from pressure, temperature,

volume, and transit time measurement

of the displaced volumes of gas. Two

types of displacers are used, bell gasometers and mercury-sealed piston/cylinder provers. Determination

of the displaced volume in either case

is based on diameter and stroke measurement. Currently, these are done

using fixed switching positions of optical or mechanical switch mechanisms for eight provers with volumes

ranging from 30 cm^ to 20 ft^ Measurements of pressure are made using

manometers and barometers. Temperature measurements are made using

contacting techniques, i.e., thermocouples, thermistors, etc. The overall

uncertainty for the air flow rate measurements is quoted to be ±0.25 percent; this is determined by summing a three standard deviation uncertainty

of ±0.15 percent, and an estimated

23
18010C-18050S

systematic error of 0. 1 percent (see

Figure 3). Details on these facilities are given by Benson et al.

Figure 3. Systematic Uncertainty of NIST Measurements

for Air Flow Rate Standards

10' 03Q.

S. 10'

10'

Piston-Type & Bell-Type Provers

Sonic Nozzles

J I

0.01

"D

fD 0.10 o

D

1 .0 10"' 10"

10"'

10 10'

ft^/min

lO-" 10"

10" "T"

10^ 10" 10° 10

meter /s Flow Rate

Large Air Flow Facility: T?.e large air flow facility consists of a compressor

as the pressure source, a dryer, set- tling chamber, meter runs (2- to 8- inch pipe sizes), and a collection tank. Flow rates from 35 to 3000 SCFM

are attainable at pressures up to 90

psig. Calibration measurements are based upon the use of a set of working standards, which are flow nozzles

operated under critical conditions,

i.e., at sonic velocity in the throat of

the nozzle. These provide an ex- tremely stable flow which is not in- fluenced by variations in downstream

pressure and temperature conditions.

Determination of the mass flow rate through these nozzles is based upon

measured discharge coefficients. Measurement of the discharge coefficient

for each nozzle over the range of

throat Reynolds numbers used is per- formed by diverting the gas flowing

through the nozzle into the collection

tank of the facility for a measured period of time. Once the gas has been

collected, a PVT measurement is used to determine the mass of gas in the tank. This value of the mass of

gas is used with the diversion time to compute the average mass flow rate through the nozzle. The overall uncertainty quoted for this flow system

is ±0.25 percent. This value is obtained as described above for the

Small Air Flow Facilities. Water Flow Facility: The water flow

facility consists of reservoir, pumps,

meter runs, and weigh tanks necessary to make primary flow measurements. Pipeline sizes up to 16 inches

in diameter are available. The system

operates as a constant flow rate facil- ity using bypass and meter-run control valves to control the pressure and flow rate in the system. Diversion into the weigh tanks is accomplished with pneumatically driven

diverter valves fitted to each of the

four weighing systems used. The

overall uncertainty for the water flow

facility is quoted to be ±0.13 percent; this is determined by summing a three standard deviation uncertainty

of ±0.03 percent, and an estimated

systematic error of ±0.1 percent.

Figure 4 summarizes the estimated

systematic uncertainty for the NIST

water flow rate standards.

Figure 4. Systematic Uncertainty of NIST l\/leasurements

for Water Flow Rate Standards

Q. 1 0

CD 10^

Dynamic Volumetric Present Proposed

B 10-

03 10" o

Dynamic Gravimetric Static Gravimetric

I I I L_

0.01

0.103

10° 10 10'

gal/min

10=* 10''1.0

1C 10"" 10"-" 10"'

meter''/s Flow Rate Hydrocarbon Flow Facilities: These

facilities have the ability to handle

a variety of hydrocarbon liquids. The

majority of the calibration requests

pertain to the use of a surrogate

liquid for JP-4 and JP-5 jet fuels as the liquid used in the calibration. Both volumetric and gravimetric sys- tems are used to calibrate flowmeters.

The flow rate range of this laboratory extends from 0.01 to approximately 400 gallons per minute. A

variety of meter types are calibrated,

although turbine meters predominate.

10" 10°

24
The overall uncertainty quoted for these systems is as given above for the Water Flow Facility. Figure 5 summarizes the estimated systematic

uncertainty for the NIST liquid hydrocarbon flow rate standards.

Figure 5. Systematic Uncertainty of NIST l\/leasurements

for Liquid Hydrocarbon Flow Rate Standards

Ib/hr 10° 10 10^ 10^ 10^ 10' 10*" 10^

10^

1 1 Prpsent1 1 1 - Static Gravimetric Proposed ....

Dynamic

Gravimetric

1 1 1

Dynamic

Volumetric

1 1 1

0.01

CD

1.0 10 ^ 10"' 10° 10 10^ 10^

gal/min

I

1 1 1 1 1

1 10"* 10"^ 10"' 10"' 10° 10 10'

kg/s

Flow Rate

Special Tests for Liquid and Gas Flow

Rates (18050S)

Special tests for liquid and gas flow

rates can be arranged. Examples can

include "in-situ" calibration of flowmeters, proving other fluid measure- ment systems, etc. Tests to establish and maintain more realistic traceability for flow measurement laboratories can be designed for specific situations. Details can be obtained and ar- rangements made through the

technical contacts listed at the beginning of this section.

References—Flow Rate Measurements

Gas Flowrate Metrology, G. E. Mattingly, Proc. Nafl. Conf. Stand.

Lab. Ann. Workshop and Symp.,

Washington, D.C., Aug. 1988. NBS Primary Calibration Facilities for Air Flow Rate, Air Speed, and

Slurry Flow, K. R. Benson, N. E. Mease, G. Kulin, and G. E. Mattingly, Proc. Intl. Flow Meas.

Symp., Washington, D.C., Nov.

1986, Amer. Gas Assoc., Arlington,

VA.

Fundamentals of Flow Measurements, J. P. DeCarlo, Instr. Soc. of

America, Research Triangle Park,

NC (1984).

Industrial Flow Measurement, D. W.

Spitzer, ISA, Research Triangle

Park, NC (1984).

Flow Measurement Engineering

Handbook, R. W. Miller, McGrawHill, New York (Jan. 1983).

A Laboratory Study of Turbine Meter Uncertainty, G. E. Mattingly,

P. E. Pontius, H. H. Allion, and

E. F. Moore, Natl. Bur. Stand.

(U.S.), Spec. Publ. 484 (Oct. 1977).

The National Measurement System

for Fluid Flow, W. C. Haight,

P. S. Klebanoff, F. W. Ruegg, and

G. Kulin, Natl. Bur. Stand. (U.S.),

NBSIR 75-930 (Aug. 1976).

Introduction to Liquid Flow Metering and Calibration of Liquid

Flowmeters, L. O. Olsen, Natl. Bur. Stand. (U.S.), Tech. Note 831

(June 1974).

Flow Measurement: Procedures and

Facilities at the National Bureau of

Standards, F. W. Ruegg and M. R. Shafer (Proc. Symp. Flow Measurement, San Francisco, CA, Jan.

19-22, 1970). Chapter in ASHRAE

(Amer. Soc. Heat Refrig. AirCond. Eng.), Bull. Flow Measurement Part 1, SF70-7, 1 (1972).

Gas Flow Measurement by Collection Time and Density in a Constant Volume, L. Olsen and

G. Baumgarten, Symposium on

Flow, Its Measurement and Control in Science and Industry, ISA,

1, Part 3, 1287 (1972).

Evaluation of a Low Flow Generator

and Calibrator as a Flow Measurement Standard, G. Baumgarten,

Natl. Bur. Stand. (U.S.), Tech. Report 10921 (1972).

Practical Considerations for Gas

Flow Measurement, M. R. Shafer,

Jr., and D. W. Baker, Proc. 3rd

Annual Prec. Meas. Assoc. Metrology Conf., Natl. Bur. Stand.,

Gaithersburg, MD, June 17-18,

1970, 1, 187 Prec. Meas. Assoc.,

Burbank, CA (1970).

Liquid-Flowmeter Calibration Techniques, M. R. Shafer and F. W.

Ruegg, ASME Paper No. 57-A-70.

Performance Characteristics of Turbine Flowmeters, M. R. Shafer,

ASME Paper No. 61-WA-25.

25
18800S

B. Flow Measurements at Cryogenic

Temperature

Technical Contacts:

Kathy Hillen AdministratiTe and Logistics

Tel: 303/497-3611 Tel: 303/497-3753

Mailing Address: M.C. 583.20, National Institute of Stan- dards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 188008 Special Tests of Cryogenic Liquid Flow

Progress Report on Cryogenic

Flowmetering at the National

Bureau of Standards, J. A.

Brennan, J. F. LaBreque, and C. H. Kneebone, Proc. 1st Biennial

Symp. Instrumentation in the Cryogenic Industry, Houston, TX, Oct.

11-14, 1976, 1, 621, Instr. Soc. of

America, Pittsburgh, PA (1976).

NBS-CGA Cryogenic Flow Measurement Program, J. A. Brennan,

R. W. Stokes, C. H. Kneebone, and

D. B. Mann (Proc. ISA Intl. In- strument. Automation Conf. and

Exhibit, New York, NY, Oct. 28-

31, 1974), Paper in Adv. in Instru- ment. 29, 612.1 (Instr. Soc. of

America, Pittsburgh, PA, 1974).

Cryogenic Flow Research Facility

Provisional Accuracy Statement,

J. W. Dean, J. A. Brennan, D. B. Mann, and C. H. Kneebone, Natl. Bur. Stand. (U.S.), Tech. Note 606

(July 1971).

Special Tests of Cryogenic Liquid

Flow (18800S)

Limited measurement services are provided for cryogenic liquid flow.

Mass flow measurements are per- formed using liquid nitrogen flow

rates of 76 to 757 liters per minute.

References—Flow Measurements at Cryogenic Temperature

Cryogenic Liquid-Measuring

Devices, Sec. 3.34, 3-57, in Specifications, Tolerances, and Other

Technical Requirements for Weighing and Measuring Devices,

O. K. Warnlof, Ed., Natl. Bur.

Stand. (U.S.), Handbook 44 (1986).

26
i 19010C-19040S

P Airspeed Measurements

Technical Contacts:

' Norman E. George E. Mease Mattingly

Tel: 301/975-5959 Tel: 301/975-5939

I Mailing Address: 105 Fluid Mechanics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

I Test No. Items 19010C Pitot-Static Tubes (3 to 150 mph)

19020C Low Airspeed Instruments (15 to 2,000 fpm)

!\ 19030S Meteorological Airspeed Instrumentation

I (3 to 150 mph)

' 19040S Special Tests of Airspeed Instruments

Airspeed Instruments (19010C-19040S)

Calibration of airspeed measuring

devices is performed in one of two

special wind tunnels (see Benson et

al.). Ellipsoidal-nosed Pitot-static tubes provide the basis of airspeed

measurement in these facilities. Pitotstatic tubes and meteorological instru- ments are calibrated in the NIST

Dual Test Section Wind Tunnel.

Low velocity airspeed measurements

are based upon laser velocimeter

measurements in the NIST Low Velocity Airflow Facility. Calibration of

the laser velocimeter is done using

the Pitot-static tube at velocities which produce a sufficiently large pressure differential in the tube that the uncertainty in the pressure

measurement does not propagate a large error into the velocity determination. Extension of the laser ve- locimeter to the low velocity region,

where the Pitot-static tube has large

measurement errors due to the inability to measure accurately the ex- tremely small pressure differentials produced via the Pitot-static tube, al- lows considerably improved measure- ment uncertainty. Air density values

in the tunnels are computed from

pressure, temperature, and humidity

measurements in the tunnels' settling

chamber.

Systematic uncertainty levels for the range of airspeed currently

offered are shown in Figure 6.

Figure 6. Systematic Uncertainty of Airspeed Measurements for Calibration of Airspeed Indicators

rt

in)

Low Velocity

Facility

COQ.

(D 10^ _ __ A C

>,

icertain 10 "^Dual Test Section Wind Tunnel

Z)

1 , , . 1 , ,,,l , , 1 , , ,,i , , , 1 ,

,,l 0.1 0.5 1.0 5 10 50 100150

Miles per Hour

I I I ,il , I I I , I ,,l ^ . . I , , ..I , .05 0.1 0.5 1.0 5.0 10 50

Meter/SecQnd

Special tests of airspeed instru- ments can be arranged. Examples in- clude "in-situ" calibration of airspeed

instrumentation, proving other air- speed measurement systems, and tests where appropriate scaling will allow

the results to be applicable to fluids other than air. Details can be obtained and arrangements made

through the technical contacts cited

at the beginning of this section.

21
19010C-19040S

Norman Mease calibrates a vane anemometer using

the LDV system in the NIST low-speed wind tunnel.

References—Airspeed Measurements

NBS Primary Calibration Facilities for Air Flow Rate, Airspeed, and

Slurry Flow, K. R. Benson, N. E. Mease, G. Kulin, and G. E. Mattingly, Proc. Intl. Flow Symp.,

Washington, D.C. (Nov. 1986),

Amer. Gas Assoc., Arlington, VA.

Experimental Investigation of Drag

on a Compliant Surface, J. M.

McMichael, P. S. Klebanoff, and

N. E. Mease, Viscous Flow Drag

Reduction, Gary R. Hough, Ed.,

Progress in Astronautics and Aeronautics, 72 (1980).

Low-Velocity Performance of

Anemometers, L. P. Purtell, Natl. Bur. Stand. (U.S.), NBSIR 79-1759

(May 1979).

A Low-Velocity Airflow Calibration

and Research Facility, L. P. Purtell and P. S. Klebanoff, Natl. Bur.

Stand. (U.S.), Tech. Note 989

(Mar. 1979).

Low-Velocity Performance of a Magnetic Pick-up Vane Anemometer,

L. P. Purtell, Natl. Bur. Stand.

(U.S.), NBSIR 79-1566 (Dec.

1978).

Low-Velocity Performance of a Ball Bearing Vane Anemometer, L. P. Purtell, Natl. Bur. Stand. (U.S.),

NBSIR 78-1485 (June 1978).

28
p.

Mass Standards

Technical Contact:

Jerry G. Keller

Tel: 301/975-4218

Mailing Address: A117 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, B33 Metrology, Gaithersburg, MD 20899-0001

Note: For weights larger than 50 lb (30 kg), contact J. G.

Keller prior to shipment.

Test No. Items 22010C

22020C

22030C

22040C

22060C

22080C

Weight Set (1 mg to 100 g)

Weight Set (1 mg to 1 kg)

Weight Set (2 to 30 kg)

Single Weights (1 mg to 1 kg)

Single Weights (2 kg to 30 kg)

Single Weights (>30 kg to 1200 kg, 2 double

substitution weighings)

22100C Single Weights (> 1200 kg to 30,000 kg)

22 HOC Single Weights (>30 kg to 1200 kg, calibrated in a weighing design)

22130C Single Weights for Deadweight Pressure Testers

(13 lb-50 lb) 22140C Single Weights for Deadweight Pressure Testers (>50 1b) 22150C Single Weights for Deadweight Pressure Testers «13 1b) 221 70S Special Mass Measurement Services 22180M Measurement Assurance Program for Mass

Mass (22010C-22110C)

NIST maintains the national stan- dards for mass in the form of the

prototype kilograms (K4 and K20)

and provides services to support the

parts of the national measurement

system that rely directly or indirectly on mass measurements. These ser- vices include the calibration of suit- able weight sets. A calibration

consists of establishing a mass value

and the appropriate uncertainty for that value for each weight that has

been designated to be a reference

standard. It is desirable, but not necessary, that a weight meet the adjustment tolerances established for Classes A, B, M, S, or S-1 prior to submission. Weights are available

from manufacturers, many of whom

can directly furnish documentation

suitable for meeting quality assurance

contracts and requirements.

For periodic recalibrations of refer- ence mass standards, the user need measure only differences between

weights or groups of weights within

a set and compare them with computed differences. As long as the

agreement is within allowable limits,

the values can be considered constant within the precision of the comparison process. Mass standards submitted to NIST for recalibration

frequently are tested in this manner.

If these tests indicate that no signifi- cant changes have occurred, a continuation report so stating and referring

to the previous NIST Report of Cali- bration will be issued. NIST calibrates individual weights

or sets in the range of 1 mg to 30 kg

or 1 lb to 50 lb in decimal subdivisions. If the weights are designated as reference standards, they must be of

design, material, and surface finish comparable to present Classes A, B,

M, S, or S-1. These include ASTM

Type I and II, grade S and O, and

OIML El, E2, and Fl. NIST also calibrates large mass standards (60 to 60,000 lbs) if the design, material, and

surface finish are compatible with the

intended usage. For these large mass

29
22010C-22180M

standards, an adjustment with refer- ence to a nominal or desired value can be included as a part of the cali- bration procedure.

The values of true mass (and an ap- parent mass correction) included in the report will be determined by us- ing computed volumes based on the

manufacturer's statement of density

of the material, or on the density

computed from measured volumes,

or, in the absence of this information, on estimated density values. However, 1-kg mass standards fabricated

from stainless steel and of one-piece

construction will have their density

determined as part of a "first-time" calibration at NIST. The apparent mass corrections are computed for 20 °C with reference to Normal Brass

(density 8.4 g/cm^ at 0 °C ind vol- ume coefficient of expansion

0.000054/°C) and to stainless steel (density 8.0 g/cm' at 20 °C) in a conventional air density of 1.2 mg/cml

Apparent mass corrections to any

other basis can be furnished if re- quested. Typical uncertainties range

from 50 parts per billion at 1 kg up to 500 parts per million at one mg and 1 part per million for weights from 2 to 30 kg. Figure 7 shows the NIST precision of weighing for mass standards over the range 10"^ to 10'* kg.

Figure 7. NIST Precision of Weighing for f^ass

Standards Ranging from 10"^ to W Kilograms

TO o

01 O) Q C

10 h • Balances & Scales

^ Elastic Devices

10*^'

10^

lO^h

_J_ _L

-.000001%

.0001 %

-.01%

- 1%

lO"'" lO"** lO"*" 10"' 10"' 1 10^ 10" 10" Load in Kilograms

Single Weights for Deadweight

Pressure Testers (22130C-22150C)

Weights less than six (6) pounds are determined by comparing them with

calibrated built-in-weights of appropriate analytical balances by the double substitution method. Weights

larger than six (6) pounds are compared to discrete standards by the

method of double transposition

weighing.

Special Mass Measurement Services

(22170S)

For tests not covered by the previous

descriptions, the NIST technical contact cited at the beginning of this section should be consulted to deter- mine whether a test can be performed

and to negotiate a price for the test. Measurement Assurance Program for Mass (22180M)

This service is most appropriate for primary calibration laboratories. Total uncertainties ranging from a few

parts in 10^ to a few parts in 10^ for

1 kg can be obtained. Unlike most

other NIST MAP services, the Mass

MAP service does not involve the use of an NIST-owned transport stan- dard that is shipped to participants

for measurement. The transfer stan- dards in the mass MAP are a set of mass standards owned by the participant and sent to NIST for calibration. These standards are referred to as the

starting standards. In addition to the

starting standards, the mass MAP

participant must also furnish a set of

much smaller weights called "sensitivity weights." The choice of both

the starting standards and the sensitivity weights will depend on the particular mass range of interest to the

participant. NIST staff can provide

advice regarding suitable starting

standards and sensitivity weights for a particular range of mass weighings.

In addition to the starting standards

and the sensitivity weights, the participating facility should have a working set of weights known as the

"test set" and a set of weights to be

used as check standards. This set

30
usually consists of weights in the

range 1 to 1000 g. This service, like other NIST MAP

services, samples the participant's

measurement process and establishes

its uncertainty. Once the participant

has become well-established in the

Mass MAP, two options are possible:

(1) NIST personnel do all of the

data analysis and record keeping for the participant and provide periodic

reports on the uncertainty of the participant's mass measurements.

(2) The participant keeps all records and calculates the uncertainties of his measurements using NIST

methods and computer codes.

The implementation of the Mass

Measurement Assurance Program in

its most complete form typically pro- ceeds in four distinct phases, which

may be abbreviated somewhat if the

participant already has a suitable mass measurement quality control system.

Phase I: Each new participant completes a questionnaire on equipment

and facilities and receives a written

description of the NIST process, methods and procedure to be used, an introduction to the interpretation

of results, and information on the use of these results in measurement decisions. At the participating laboratory,

the suitability of the weighing equipment is verified, the starting stan- dards selected or procured, and if the

procedures are entirely new, operators are trained. The starting stan- dards and sensitivity weights are sent

to NIST for calibration. If the start- ing standards have a prior NIST cali- bration history, those data are reviewed, and if satisfactory, they are considered, along with the data from

the more recent determinations, in ar- riving at assigned values for the start- ing standards. NIST will recommend

a weighing design to be used for cali- brating the test weight. This weighing design prescribes the set of

observations for intercomparing the

test weights with known weights.

NIST will also supply data sheets

that are used throughout the first three phases of the program for recording data taken using the design.

The objective of the first phase is to ensure that the new participant is fa- miliar with good laboratory practices

for high precision weighing. If the

participating laboratory has an estab- lished mass measurement capability

and an existing quality control procedure for mass measurements. Phase I

is abbreviated considerably.

Phase II: The starting standards and

sensitivity weights are returned to the

participant and, following the pre- scribed precedures, measurements are made over a period of time by the

participant to verify that a state of

statistical control exists. The data

sheets are sent to NIST for review,

comments, and processing after each

measurement. If there are unanticipated problems, or the procedure has not been followed exactly, more measurements may be required. After

three or more successful calibrations

in the user's facility, NIST analyzes

the data to determine the values of

the check standards.

Phase III: A comprehensive report is issued by NIST that contains a re- view of the actions and decisions in each of the phases, control charts for the check standards to be used in the

participant's facility, and a comparison of the values assigned to the

starting standards by NIST and by

the participant. It is assumed at this point that the participating facility is now ready to extend the operation of

the MAP to its regular workload.

Phase IV: Having thus established

measurement comparability, the MAP

user can then, in principle, operate in- dependently of NIST. As long as there is no indication of a loss of

statistical control of the process, no

further checking with NIST should

be necessary. Most participants re- quest a recheck of the starting stan- dards every few years to ensure that no undetected long-term drift has

taken place.

31
For work that differs from the

items normally calibrated by the participant, NIST can provide consulting

help and assistance necessary to ac- commodate a greater range of

weights, calibrate pound standards,

and extend pound standards to large

weights normally associated with

force measurement. Although the

usual Mass MAP service uses two

1-kg masses as the starting standards,

the program is sufficiently flexible that the same methods can be used

with other mass values.

References—Mass Standards

A Primer for Mass Metrology, K. B. Jaeger and R. S. Davis, Natl. Bur.

Stand. (U.S.), Spec. Publ. 700-1

(Nov. 1984).

Air Buoyancy Correction m HighAccuracy Weighing on Analytical

Balances, R. M. Schoonover and

F. E. Jones, Anal. Chem., 53, No.

6, 900 (May 1981).

National Bureau of Standards Mass

Calibration Computer Software,

R. N. Varner and R. C. Raybold,

Natl. Bur. Stand. (U.S.), Tech.

Note 1127 (July 1980).

Quick and Accurate Density Deter- mination of Laboratory Weights,

R. M. Schoonover and R. S. Davis,

Proceedings of the 8th Conference

of IMEKO, Krakow, Poland

(1980).

Precision Laboratory Standards of

Mass and Laboratory Weights. A

reprint of NBS Circular 547, Section 1, T. W. Lashof and L. B. Macurdy, August 1954, Natl. Bur.

Stand. (U.S.), NBSIR 78-1476 (Oct.

1978).

The National Measurement System

for Mass, Volume, and Density,

P. E. Pontius, J. R. Whetstone, and

J. A. Simpson, Natl. Bur. Stand.

(U.S.), NBSIR 75-928 (May 1978).

Direct Determination of Air Density

in a Balance through Artifacts

Characterized in an Evacuated

Weighing Chamber, W. F. Koch,

R. S. Davis, and V. E. Bower, J. Res. Natl. Bur. Stand. (U.S.), 83,

No. 5, 407 (Sept.-Oct. 1978).

The Air Density Equation and the

Transfer of the Mass Unit, F. E.

Jones, J. Res. Natl. Bur. Stand.

(U.S.), 83, No. 5, 419 (Sept.-Oct.

1978).

Designs for the Calibration of Stan- dards of Mass, J. M. Cameron,

M.C. Croarkin, and R. C. Raybold,

Natl. Bur. Stand. (U.S.), Tech.

Note 952 (June 1977).

The Air Density Equation and the

Transfer of the Mass Unit, F. E.

Jones, Natl. Bur. Stand. (U.S.),

NBSIR 77-1278 (July 1977).

Measurement Assurance, J. M.

Cameron, Natl. Bur. Stand. (U.S.),

NBSIR 77-1240 (1977).

Surveillance Test Procedures, H. W.

Aimer, Natl. Bur. Stand. (U.S.),

NBSIR 76-999 (Feb. 1976).

Mass and Mass Values, P. E. Pontius,

Natl. Bur. Stand. (U.S.), Monogr.

133 (Jan. 1974).

Weight Cleaning Procedures, H. E. Aimer, Natl. Bur. Stand. (U.S.),

NBSIR 74-443 (Nov. 1973).

On Uncertainty in Mass Measurement, J. R. Donaldson, Natl. Bur.

Stand. (U.S.), NBSIR 73-151 (Mar.

1973).

Method of Calibrating Weights for Piston Gages, H. E. Aimer, Natl. Bur. Stand. (U.S.), Tech. Note 577

(May 1971). Realistic Uncertainties and the Mass

Measurement Process, P. E. Pontius and J. M. Cameron, Natl. Bur. Stand. (U.S.), Monogr. 103

(Aug. 1967).

Introduction to Intercomparison

Methods in Mass Measurement,

H. E. Aimer, Natl. Bur. Stand.

(U.S.), Report 9487 (Feb. 1967).

Measurement Philosophy of the Pilot Program for Mass Calibration,

P. E. Pontius, Natl. Bur. Stand.

(U.S.), Tech. Note 288 (May 1966).

32
Simone L. Robert W.

Yaniv Peterson

Tel: 301/975-6655 Tel: 301/975-6649

Mailing Address: 221 Engineering Mechanics, National

1 Institute of Standards and Technology, Gaithersburg,

MD 20899-0001

Test No. Items

230 IOC Force Transducers (to 25,000 Ibf, 1 mode)

23020C Extra observation

23030C Additional bridges

23040C Force Transducers (to 25,000 Ibf, 2 modes)

23050C Extra observation

23060C Additional bridges

23070C Force Transducers (25,001 to 112,000 Ibf, 1 mode)

23080C Extra observation

23090C Additional bridges

23100C Force Transducers (25,001 to 112,000 Ibf, 2 modes)

23 HOC Extra observation

23120C Additional bridges

23130C Force Transducers (112,001 to 300,000 Ibf, 1 mode)

23140C Extra observation

23150C Additional bridges

23160C Force Transducers (112,001 to 300,000 Ibf, 2 modes)

23170C Extra observation

23180C Additional bridges

23190C Force Transducers (300,001 to 1,000,000 Ibf, 1 mode)

23200C Extra observation

23210C Additional bridges

23220C Force Transducers (300,001 to 1,000,000 Ibf, 2 modes)

23230C Extra observation

23240C Additional bridges

23250C Force Transducers (over 1,000,000 Ibf) 23260S Special Tests of Force Transducers

Force Transducers (23010C-23250C)

NIST provides calibration services

for force measuring devices by applying known forces, either tension or compression, to the elastic device and

recording the sensed deformation.

Most of the devices calibrated are ei- ther proving rings or load cells. The

deformation of proving rings is usually measured by means of a micrometer screw and vibrating reed, which

are an integral part of the device.

Load cells, which utilize strain gauge

bridges, produce an electrical output

that is related to the applied force. The calibration report describes the

relationship between the applied

force and the measured deformation,

either in electrical or mechanical

units. A load cell can be calibrated

using (1) a readout device furnished

by the customer, in which case the

load cell and the readout device are

calibrated as a system, and the cali- bration is valid only when the load

cell and the readout device are used

together; or (2) instrumentation fur- nished by NIST, in which case data

are reported in terms of the ratio of

the output voltage to the DC excita- tion voltage (mVA^). In the latter case, the customer must possess the

necessary electrical instrumentation

and expertise to utilize the calibration

results. Tension or compression calibra- tions in the range of 100 pounds-force

(Ibf) to 1,000,000 Ibf are performed

using deadweight machines. NIST

has six such deadweight machines

with maximum capacities of 500;

6,100; 25,300; 112,000; 300,000; and

1,000,000 Ibf. The four larger machines allow the force applied to the

unit being calibrated to be incre- mented or decremented without having to return to zero load between

33
force applications. When using the

two smaller machines it is necessary

to go to zero load before the load is changed. The estimated uncertainty

of the vertical component of the applied force is 20 ppm.

Comparison calibrations in the

range of 1,000,000 Ibf to 12,000,000

Ibf in compression only are per- formed in a universal testing machine.

In this case, the system being cali- brated is loaded in series with load

cells that have been previously cali- brated in a deadweight machine.

Special Tests of Force Transducers

(23260S)

Temperature sensitivity, pressure sensitivity, eccentric-load sensitivity, and

creep tests of force transducers are measured. The ranges of t( st parameters and environmental conditions

may be limited by the characteristics

of the force transducer and the

availability of special test fixtures. These special tests should be dis- cussed with the designated NIST

technical contact before the work is scheduled.

References—Force Measurements

Interlaboratory Comparison of Force

Calibrations Using ASTM Method

E74-74, R. W. Peterson, L. Jenkins,

and R. A. Mitchell, Natl. Bur.

Stand. (U.S.), Tech. Note 1211

(Apr. 1985).

Metrological Regulations for Load

Cells, OIML International Recommendation No. 60, Intl. Org. for Legal Metrol, Paris (Oct. 1984).

Progress in Force Measurement at NBS, R. A. Mitchell, Proc. 10th

Conf IMEKO TC-3 on Measurement of Force and Mass, Kobe,

Japan (Sept. 1984).

Inherent Problems in Force Measurements, P. E. Pontius and R. A.

Mitchell, Exper. Mech., 22, No. 3 (Mar. 1982).

Force Sensor-Machine Interaction, R. A. Mitchell and P. E. Pontius,

Proceedings of the 27th International Instrumentation Symposium

(ISA), Indianapolis, IN, Instrumentation in the Aerospace Industry,

27, 225 (1981).

Characterizing the Creep Response of

Load Cells, R. A. Mitchell and

S. M. Baker, VDI-Berichte 312, 43

(1978).

Interlaboratory Comparison of Force

Calibrations Using ASTM Method

E74-74, Phase I, R. W. Peterson and R. L. Bloss, Natl. Bur. Stand.

(U.S.), NBSIR 76-1145 (Aug.

1976).

A Study of the National Force Measurement System, D. E. Marlowe,

Natl. Bur. Stand. (U.S.), NBSIR

75-929 (June 1975).

Universal Testing Machine of 12- Million-lbf Capacity at the National

Bureau of Standards, A. F. Kirstein, Natl. Bur. Stand. (U.S.),

Spec. Publ. 355 (Sept. 1971).

Studies of Calibration Procedures for Load Cells and Proving Rings as Weighing Devices, G. B. Anderson

and R. C. Raybold, Natl. Bur.

Stand. (U.S.), Tech. Note 436 (Jan.

1969).

Gravity Measurements and the Stan- dards Laboratory, D. R. Tate,

Natl. Bur. Stand. (U.S.), Tech.

Note 491 (Aug. 1969).

Uncertainties Associated with Proving Ring Calibration, T. E. Hockersmith and H. H. Ku, Preprint No. 12.3-2-64 ISA Conference, Instr. Soc. of America, Res. Triangle Park, NC (Oct. 1964).

34
24010C-24060S

F.

Vibration Measurements

Technical Contacts:

Beverly F. Payne

Tel: 301/975-6639

Donald C. Robinson

Tel: 301/975-6643

Myroslav R. Serbyn

Tel: 301/975-6646

Mailing Address: A149 Sound, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items Freq. Range Peak Accel. Uncer. in %

24010C Pickup

Sensitivity

2 to 160 Hz 0.2 to 2 g ±1 to ±2

24020C Pickup

Sensitivity

10 to 3500 Hz 2 to 10 g ±1 to ±2

24O30C Pickup

Sensitivity

10 Hz to 10 kHz 2 to 10 g ±1 to ±2

24040S Shock

Measurement

10 Hz to 10 kHz 50 to 5000 g ±3 to ±5

24050S Pickup

Sensitivity

3 to 20 kHz 4 to 200 g ±1 to ±3

24060S Special Vibration Tests, by Prearrangement

Pickup Sensitivity (24010C-24030C)

NIST calibrations of vibration exciters and pickups are performed by

comparison with the response characteristics of NIST standards or by ab- solute measurements. A calibration

consists of measuring the transfer function of the instrument, usually re- ferred to as the sensitivity. For a pickup it is the ratio of the electrical output to a mechanical input. The

magnitude of the latter is set in ac- cordance with the calibration

method, the type of vibration exciter,

and the frequency of vibration. The

magnitude of the output depends, of

course, on the nature of the test device. In the case of an accelerometer with signal conditioner, the practice has been to express the output in millivolts, and the input in units of gn, the standard acceleration of free

fall. The acceleration sensitivity is then given in mV/g. For chargeoutput devices without signal conditioners, the acceleration sensitivity is stated in picocoulombs per g (pC/g).

All measurements are performed at 23±3 °C and 50±10 percent r.h. The calibration of an accelerometer

is reported in tabular form as the sensitivity magnitude at a set of discrete

frequencies; the phase component can be furnished on request, at additional

cost. The NIST vibration standards are

periodically calibrated by reciprocity

and/or interferometric techniques,

two independent and absolute methods. The use of these standards in the

calibration of stable transducers fur- nishes calibration data with a typical

uncertainty of 1 to 2 percent depending on the frequency range.

Special Shock Measurement Services

(24040S)

The shock facility provides a comparison calibration of accelerometers

by subjecting them to half-sinewave

pulses with peak amplitudes of 50 to 5000 g and pulse widths from 0.2 to 40 milliseconds. Both time and fre- quency domain measurements can be

performed.

Special Tests of Pickup Sensitivity

(24050S)

This test measures the pickup sensitivity by the fringe-disappearance

method, using an automated Michelson interferometer. As presently configured, the system operates between

3 kHz and 20 kHz. The method re- quires precise setting of vibration amplitude to 121.10 nm; consequently,

the acceleration amplitude in the

stated frequency range increases from

about 4 to 200 g.

Special Vibration Tests (24060S)

Calibration of vibration and shock

measuring instruments to specifications different from those above as

35
well as other measurements can be

performed by prearrangement. For

example, a comparison calibration for frequencies greater than 10 kHz can

be performed on request. Consult

with the technical contacts cited at the beginning of this section.

References—Vibration Measurements

An Application of Parameter Estimation Theory in Low Frequency

Accelerometers, B. F. Payne and

M. R. Serbyn, 14th Transducer

Workshop, Telemetry Group,

Range Commanders Council, Colorado Springs, CO (June 1987).

A Description of NBS Calibration

Services in Mechanical Vibration

and Shock, D. C. Robinson, M. R. Serbyn, and B. F. Payne. Natl. Bur. Stand. (U.S.), Tech. Note

1232 (Feb. 1987).

An Automated Fringe Counting

Laser Interferometer for Low Fre- quency Vibration Measurements,

B. F. Payne, Proc. ISA Symp.,

Seattle, WA (May 1986).

Automation of Vibration Testing at the National Bureau of Standards,

B. F. Payne, Proc. 30th Tech.

Meeting, Inst, of Environ. Sciences

(May 1984).

An Automated System for the Measurement of Pickup Sensitivity, B. F. Payne and M. R. Serbyn,

NCSL 1983 Workshop and Symposium Proceedings, II- 1 1.1 -II- 1 1.22 (July 1983).

The Application of Back-to-Back

Accelerometers to Precision Vibration Measurements, B. F. Payne,

J. Res. Natl. Bur. Stand. (U.S.), 88,

No. 3, 171 (May-June 1983).

A Real-Time Active Vibration Controller, M. R. Serbyn and W. B. Penzes, ISA Transactions, 21, No.

3, 55 (1982).

Development of a Low-FrequencyVibration Calibration System, R. S. Koyanagi, Exp. Mech., 15, 443

(Nov. 1975).

Shock Calibration of Accelerometers,

C. Federman, W. Walston, and J. Ramboz, Minutes of the 8th Trans- ducer Workshop: Telemetry

Group, Inter-Range Instrumentation Group, Range Commanders

Council, Wright-Patterson AFB,

OH (Apr. 1975).

Piezoelectric Shakers for WideFrequency Calibration of Vibration

Pickups, E. Jones, B. Yelon, and

S. Edelman, J. Acoust. Soc. Am.,

46, No. 6, 1556 (June 1969).

Improved Transfer Standard for Vibration Pickups, E. Jones, D. Lee,

and S. Edelman, J. Acoust. Soc. Am., 41, No. 2, 354 (Feb. 1967).

Electrodynamic Vibration Standard

with a Ceramic Moving Element,

T. Dimoff, J. Acoust. Soc. Am.,

40, No. 3, 671 (Sept. 1966).

Calibration of Vibration Pickups at Large Amplitudes, E. Jones, S. Edelman, and K. S. Sizemore,

J. Acoust. Soc. Am., 33, No. 11, 1462 (Nov. 1961).

Calibration of Vibration Pickups by

the Reciprocity Method, S. Levy

and R. R. Bouche, J. Res. Natl. Bur. Stand. (U.S.), 57, No. 4, 227

(Oct. 1956).

36
Acoustic Measurements

Technical Contact:

Victor Nedzelnitsky

Tel: 301/975-6638

Mailing Address: A147 Sound, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 25010C Pressure Response: WE Type 640AA microphones or

equivalent (e.g., Tokyo Riko Type ECL MR103, Bruel & Kjaer Type 4160, Bruel & Kjaer Types 4144

or 4132 with DBOlll adapter). 50 to 10,000 Hz. 25020C Pressure Response: WE Type 640AA microphones or

equivalent (e.g., Tokyo Riko Type ECL MR103;

Bruel & Kjaer Type 4160; Bruel & Kjaer Types 4144

or 4132 with DBOlll adapter). 50 to 20,000 Hz. 25030C Pressure Response: Tokyo Riko Type ECL MRl 12, Bruel & Kjaer Type 4134, or equivalent half-inch microphones, 50 to 10,000 Hz. 25040C Pressure Response: Tokyo Riko Type ECL MRl 12, Bruel & Kjaer Type 4134, or equivalent half-inch microphones, 50 to 20,000 Hz. 25050C Free-Field Response: Tokyo Riko Type ECL MRl 12, Bruel & Kjaer Types 4133, 4134, 4165, 4166, or

equivalent half-inch microphones, 2,500 to 20,000 Hz. 25060S Special Tests of Acoustic Devices

25070S Special Tests of Earphones

Pressure and Free-Field Response of

Microphones (25010C-25050C)

Pressure calibrations (Test Nos.

250 IOC and 25020C) are performed on Type-L 1-inch microphones satis- fying the requirements of American

National Standard SI. 12- 1967

(R1977), Specifications for Laboratory Standard Microphones and its impending revision. The microphones

submitted for pressure calibration

must be suitable for use with the cali- brating couplers shown in Figures 6 and 10 of the applicable American

National Standard SI. 10-1966

(R1986). Pressure calibrations are reported

in terms of open-circuit voltage per

unit sound pressure applied uniformly

to the diaphragm. The open-circuit

voltage at the electrical terminals of a microphone may be influenced by

stray capacitance evident at these ter- minals. For Type-L microphones,

these capacitances are defined by the geometrical configuration of the

ground shield shown in Figures 6 and

13 of SI. 10-1966 (R1986). If the

ground shield dimensions are not adhered to in making use of the re- sponse levels reported by NIST,

errors may result. Pressure calibra- tions of Type-L microphones exhibit

typical uncertainties of approximately

0. 1 dB or less at frequencies from 50

Hz to 8 kHz, and 0.2 dB or less at frequencies from 8 kHz to 20 kHz.

Further information is contained in the references for acoustic measurements. Since American National Standards

Institute publications SI. 10-1966

(R1986) and SI. 12-1967 (R1977) were

issued, certain types of half-inch di- ameter precision microphones have

attained widespread use. Therefore,

NIST has developed procedures

(Test Nos. 25030C and 25040C) for determining the pressure response

levels of half-inch microphones by

comparison with NIST-owned TypeL standard microphones, which in turn are calibrated periodically by the

reciprocity technique. The technique

used, precautions to be observed, and

uncertainties of measurement are es- sentially the same as those given

above for one-inch microphones. Significantly different aspects of the pro- cedures for half-inch microphones,

such as ground shield configuration,

are described in the test report. Since

several half-inch laboratory standard

microphones have been available for

37
only a relatively short time, their long-term stability has yet to be determined.

The free-field response levels of

certain Type-L microphones (e.g., Western Electric Type 640AA con- denser microphones) can be computed from pressure response levels reported by NIST. However, certain

precautions must be taken, and there

is some degradation in accuracy. Therefore, for the most demanding

free-field measurement requirements,

NIST offers a calibration service

(Test No. 25050C) for determining

the free-field response levels for half- inch microphones. The calibrations are made over the frequency range of

2.5 kHz to 20 kHz at normal inci- dence. Response levels (sensitivity

levels) are reported in terns of opencircuit voltage per unit sound pres- sure (in the absence of the microphone) of a plane progressive wave

whose direction of propagation is normal to the plane of the dia- phragm. The calibrations are per- formed in a well-characterized ane- choic chamber. A typical uncertainty

in this calibration is approximately

0.15 dB or less at each frequency

within the range of 2.5 kHz to 20

kHz. Calibrations can be performed

with or without protective grids on

the microphone. For the most precise

free-field measurements, the customer

should contact the NIST staff person

cited at the beginning of this section

for recommendations prior to submitting the microphone to NIST for cal- ibration.

Special Tests of Acoustic Devices

(25060S)

Acoustical measurement services are

available by special arrangement.

These services include extended fre- quency ranges of calibration, additional data points, measurements at very low sound pressure levels, and

calibration of certain pistonphones

and acoustic calibrators. NIST has a

large general-purpose anechoic chamber available for special calibrations

requiring such a facility. The fre- quency-dependent and positiondependent acoustical performance of

this chamber, including extremely

low background noise, was carefully

controlled during design and construction and is documented in archival journal publications.

Special Tests of Earphones (25070S)

Earphones are tested on the

NIST 9-A Coupler from 125 to 8000

Hz. Measurements of audiometer/

earphone response and linearity can

be made at very low sound pressure

levels.

References—Acoustic Measurements

Free-Field Reciprocity Calibration of

Microphones, E. D. Burnett and

V. Nedzelnitsky, J. Res. Natl. Bur.

Stand. (U.S.), 92, No. 2, 129 (Mar.-

April 1987).

Traceability of Acoustical Instrument

Calibration to the National Bureau

of Standards, V. Nedzelnitsky,

Proc. INTER-NOISE 80, II, Dec.

8-10, 1980, Miami, FL, G. C. Maling, Jr., Ed., Poughkeepsie,

NY: Noise Control Foundation,

1043 (1980).

Calibration of Laboratory Condenser

Microphones, V. Nedzelnitsky,

E. D. Burnett, and W. B. Penzes,

Proceedings of the 10th Transducer

Workshop, Transducer Committee,

Telemetry Group, Range Commanders Council, Colorado Springs,

CO (June 1979).

Acoustical Properties of the National

Bureau of Standards Anechoic

Chamber, W. Koidan and G. R. Hruska, J. Acoust. Soc. Am., 64,

No. 2, 501 (Aug. 1978).

Specifications for Laboratory

Standard Microphones, American

National Standards Institute, SI. 12- 1967 (R1977), New York,

NY.

38
Method for Calibration of Microphones, American National Stan- dards Institute, SI. 10-1966 (R1986),

New York, NY.

Wedge Design for the National

Bureau of Standards Anechoic

Chamber, W. Koidan, G. R. Hruska, and M. A. Pickett,

J. Acoust. Soc. Am., 52, No. 4

(Part 1), 1071 (1972).

Calibration of Standard Condenser

Microphones: Coupler Versus

Electrostatic Actuator, W. Koidan,

J. Acoust. Soc. Am., 44, No. 5, 1451 (Nov. 1968).

Calibrations of Microphones, Vibration Pickups, and Earphones, R. K.

Cook, S. Edelman, and W. Koidan,

J. Audio Eng. Soc, 13, No. 4 (Oct.

1965).

Free-Field Correction for Condenser

Microphones, W. Koidan and D. S. Siegel, J. Acoust. Soc. Am., 36,

No. 11, 2233 (Nov. 1964).

Hydrogen Retention System for Pres- sure Calibration of Microphones in Small Couplers, W. Koidan, J. Acoust. Soc. Am., 35, No. 4, 614

(Apr. 1963).

Method of Measurement of | E'/I' | in the Reciprocity Calibration of Condenser Microphones, W. Koidan,

J. Acoust. Soc. Am., 32, No. 5, 611

(May 1960).

39
26030S-26070S

Ultrasonic Reference Block Measurements

Technical Contacts:

Gerald V. Donald G.

Blessing Eitzen

Tel: 301/975-6627 Tel: 301/975-6624

Mailing Address: A147 Sound, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 26030S Special Tests of Area/Amplitude Aluminum

Reference Blocks—Set of Eight Blocks

26040S Each additional block/measurement

26050S Special Tests of Distance/Amplitude Aluminum

Reference Blocks—Set of Fifteen Blocks

26060S Each additional block/measurement

26070S Special Tests of Amplitude or Velocity

Reference Blocks

Special Tests of Aluminum Reference

Blocks (26030S-26060S)

The ultrasonic response of 7075 alu- minum alloy reference blocks of 0.50

inch and greater metal path distances

is determined relative to an NIST ref- erence standard. The immersion,

pulse-echo, longitudinal wave, 5 MHz

quartz transducer testing system defined in the ASTM E-127 calibration

document is used with some procedural modifications. In the NISTdeveloped procedure, the interim ref- erence standards are calibrated

along with the customer's blocks. System precision and stability over

time are provided by the set of in- terim reference standard ("check

standard") blocks with flat-bottom

hole sizes of 3/64-, 5/64-, and 8/64-

inch diameter. Standard deviation

data, representing random errors as- sociated with the NIST system, are provided for the respective block and

hole sizes. The plus or minus two

standard deviation uncertainty levels range from about 3 to 10 percent of

block response, depending on the

block and hole sizes of the respective

check standards. A comparison of the customer's block value to the data

base of all blocks measured by NIST

is also available. Response following

the procedures of the ASTM Recommended Practice E-127 can also be

determined. In addition, the response

of some blocks with metal path dis- tances less than 0.50 inch can be obtained by special arrangement.

Special Tests of Amplitude or Velocity

Reference Blocks (26070S)

Steel and titanium ultrasonic refer- ence blocks can be calibrated using

procedures similar to those described

in ASTM E-428.

Ultrasonic transit-time measure- ments of the customer's supplied

blocks can be determined, from

which the material velocity may be

determined.

40
References—Ultrasonic Reference

Block Measurements

Standard Practice for Fabricating and

Checking Aluminum Alloy Ultra- sonic Standard Reference Blocks,

E- 127-82A, in Annual Book of

ASTM Standards, Vol. 03.03,

Philadelphia, PA, Amer. Soc. for Testing and Materials (1985).

An Assessment of Ultrasonic Refer- ence Block Calibration Methodology, G. V. Blessing, Natl. Bur. Stand. (U.S.), NBSIR 83-2710

(June 1983).

Recent Improvements to the ASTMType Ultrasonic Reference Block

System, D. J. Chwirut, Natl. Bur. Stand. (U.S.), NBSIR 79-1742

(Feb. 1979).

The Evaluation of Search Units Used

for Ultrasonic Reference Block

Calibrations, D. J. Chwirut and

G. D. Boswell, Natl. Bur. Stand.

(U.S.), NBSIR 78-1454 (Feb. 1978).

Improved Ultrasonic Standard Refer- ence Blocks, G.F. Sushinsky, D. G.

Eitzen, D. J. Chwirut, C. J. Bechtoldt, and A.W. Ruff, Natl. Bur. Stand. (U.S.), NBSIR 76-984

(Nov. 1976).

Procedures for the Calibration of

ASTM E127-Type Ultrasonic Ref- erence Blocks, D. J. Chwirut,

G. F. Sushinsky, and D. G. Eitzen,

Natl. Bur. Stand. (U.S.), Tech.

Note 924 (Sept. 1976).

41
26100C-26120S

Ultrasonic Transducer Measurements

Technical Contacts:

Steven E. Pick Donald G. Eitzen

Tel: 301/975-6629 Tel: 301/975-6624

Mailing Address: A147 Sound, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 26100C Ultrasonic Transducer Power Output; Aadiation

Pressure 26110C Ultrasonic System Power Output; Calorimeter

26120S Special Tests of Ultrasonic Transducers

Ultrasonic Transducer Power and

Frequency (26100C-26110C)

Measurements of total ultrasonic for- ward power radiated into a water

load are offered for the purpose of

characterizing ultrasonic systems and

transducers. Ultrasonic systems are characterized by measurement of out- put under operating conditions specified by the customer. Transducers for which an amplitude-modulated con- tinuous-wave electrical input voltage can accurately and reproducibly be

measured are characterized by a radi- ation conductance determined from

measurements of input voltage and

output power. A typical calibration

report for an ultrasonic system pro- vides the results of at least three measurements of output power for each

operating condition specified. Cali- bration reports for transducers typically present a single value of

radiation conductance derived from

at least 15 measurements spanning an

appropriate range of power. Reso- nance frequencies of transducers are determined from the results of iterative spot-frequency relative measure- ments of radiation conductance.

Continuous-wave ultrasonic power

is determined from the force required

to arrest the motion of a conical

target that diverts the output beam of

the transducer under test into a bank

of absorbers. Absolute power can be

measured at spot frequencies between

1 and 20 MHz. The overall uncertainty varies from 2.2 percent at 1 MHz to 7.6 percent at 20 MHz.

These estimates of uncertainty apply

to measurements made at power levels ranging from a few milliwatts to a few watts; the minimum detectable

power is about 10 microwatts while

high-power measurements are limited

by the onset of cavitation in the water load. Transducers of diameter no

greater than 45 mm can be tested in

this apparatus.

Pulsed ultrasonic power is measured using a specially designed

calorimeter. With pulsed excitation,

only ultrasonic systems comprising a transducer and an electrical driver can be tested. Transducers by themselves cannot be independently characterized with pulsed drive waveforms since the electrical input signals

cannot at present be adequately measured or characterized. Power levels ranging from 1 mW to several watts

at frequencies between 1 and 15 MHz

can be measured with an overall uncertainty less than 10 percent + 0.2 mW. Transducers with diameters as great as 26 mm can be accommodated. Measurements of continuous- wave power are also possible with

the calorimeter; its response time pre- cludes swept-frequency tests.

Special Tests of Ultrasonic Transducer

Power (26120S)

This service includes consultation,

customized testing, and the lending of

air-backed transducers for the pur- pose of transferring power measurements. Quartz transducers characterized by radiation conduc42
tance and thus suited for the repro- duction of arbitrary power levels are

available for frequencies of 2, 3, and

5 MHz and can be specially cali- brated for operation at odd overtones. Lithium niobate transducers

with built-in circuitry allowing the

field user to reproduce prearranged

power levels while measuring only dc

voltage are available for use at fre- quencies below 20 MHz approximated by odd multiples of 0.5 MHz.

References—Ultrasonic Transducer

Measurements

An Ultrasonic Absolute Power

Transfer Standard, S. E. Pick,

F. R. Breckenridge, C. E. Tschiegg, and D. G. Eitzen, J. Res.

Natl. Bur. Stand. (U.S.), 89, No. 2, 209 (Mar. 1984).

Ultrasonic Transducer Characterization at the NBS, E. R. Miller and

D. G. Eitzen, IEEE Trans. Sonics

and Ultrasonics, SU-26, No. 1, 28

(Jan. 1979).

Ultrasonic Transducer Power Output

by Modulated Radiation Pressure (with details), M. Greenspan, F. R. Breckenridge, and C. E. Tschiegg,

Natl. Bur. Stand. (U.S.), NBSIR

78-1520 (July 1978).

Ultrasonic Transducer Power Output

by Modulated Radiation Pressure,

M. Greenspan, F. R. Breckenridge,

and C. E. Tschiegg, J. Acoust.

Soc. Am., 63, No. 4, 1031 (Apr.

1978).

Ultrasonic Calorimeter for Beam

Power Measurements from 1 to 15 Megahertz, T. L. Zapf, M. E. Harvey, N. T. Larsen, and R. E.

Stoltenberg, 1976 Ultrasonics Symposium Proceedings, IEEE Cat. 76,

CH1120-ISU, Inst, for Electron,

and Electric. Engrs., New York,

NY (1976).

Ultrasonic Calorimeter for Beam

Power Measurements, T. L. Zapf,

M. E. Harvey, N. T. Larsen, and

R. E. Stoltenberg, Natl. Bur.

Stand. (U.S.), Tech. Note 686

(Sept. 1976).

Calibration of Quartz Transducers as Ultrasonic Power Standards by an

Electrical Method, T. L. Zapf,

1974 Ultrasonics Symposium Proceedings, IEEE Cat. 74, CH0896-

ISU, Inst, for Electron, and

Electric. Engrs., New York, NY

(1974).

43
26200C-26210S

Acoustic Emission Transducer Measurements

Technical Contacts:

Franklin R. Donald G.

Breckenridge Eitzen

Tel: 301/975-6628 Tel: 301/975-6624

Mailing Address: A147 Sound, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 26200C Acoustic Emission Transducer Amplitude and Phase

Sensitivity versus Frequency

2621 OS Special Tests of Acoustic Emission Transducers and

Sensors

Acoustic Emission Sensors (26200C)

The NIST acoustic emission trans- ducer calibration provides the voltage

output of a transducer per unit of

motion (displacement or velocity) of

the mounting surface as a function of

frequency. The calibration is based

upon the normal component of motion which would occur in the ab- sence of the transducer. A choice of

two different geometries for the test

is offered as follows: the surface- pulse test in which the transducer un- der test and the source of sound are both on a common plane surface of

the test block, and the through-pulse

test in which the transducer under

test and the source of sound are lo- cated on opposite faces of the test block.

The surface-pulse test method is as follows: a step function of "point"

force is generated on the surface of a

large steel block by breaking a glass

capillary. The transducer under test and the NIST standard capacitive

transducer are located on this same

surface and are equidistant from the

source. Both transducers experience

the motion of the seismic surface

pulse generated by the step function

force. The transient voltage outputs

from both transducers are recorded

and analyzed for frequency content. The frequency response of the trans- ducer under test is obtained by dividing the spectral amplitude from it by

that from the standard transducer,

frequency by frequency. The calibra- tion is absolute, since the sensitivity

of the standard transducer is known.

The magnitude and phase of the sensitivity of the transducer under test are obtained at discrete frequencies,

f„ = 9765.625n (Hz), where n= 1,2,3... The customer is provided with the

results in the form of graphs of magnitude and phase. These are piecewise linear functions constructed

through the data points. Within the

valid range of 0. 1 to 1 MHz, the uncertainty is approximately 10 percent.

At the option of the customer, the re- sults will be given with respect to normal displacement or velocity of

the mounting surface, on a linear scale or on a decibel scale. The through-pulse test method is similar to the surface-pulse test, ex- cept that the transducer under test and the source of sound are located

opposite each other on the top and

bottom plane surfaces of the 43-cmthick test block. For the throughpulse calibration, the reference signal

is obtained not from the standard

transducer but from a calculation

based on the measured force of the

capillary break.

44
26200C-26210S

References—Acoustic Emission

Transducer Measurements

Acoustic Emission Transducer Cali- bration by Means of the Seismic

Surface Pulse, F. R. Breckenridge,

J. Acoust. Emission, 1, No. 2 (Apr.

1985).

Calibration and Sensor Activities,

D. G. Eitzen, F. R. Breckenridge,

R. B. Clough, E. R. Fuller, N. N.

Hsu, and J. A. Simmons, Chapter

2.0 in Fundamental Developments

for Quantitative Acoustic Emission

Measurements, EPRI NP-2089, Research Project 608-1, Palo Alto,

CA, Electric Power Research Insti- tute, 2-1-2-52 (Oct. 1981).

Surface-Wave Displacement:

Absolute Measurements Using a Capacitive Transducer, F. R. Breckenridge and M. Greenspan,

J. Acoust. Soc. Am., 69, No. 4, 1177 (Apr. 1981).

Characterization and Calibration of

Acoustic Emission Sensors, N. N. Hsu and F. R. Breckenridge, Matls.

Eval., 39, No. 1, 60 (Jan. 1981).

Acoustic Emission: Some Applications of Lamb's Problem, F. R. Breckenridge, C. E. Tschiegg, and

M. Greenspan, J. Acoust. Soc. Am., 57, No. 3, 626 (Mar. 1975).

45
Chapter

A Pressure Measurements B Low-Pressure, Vacuum,

and Leak Measurements O Laboratory Thermometers

D Thermocouples, Thermocouple

Materials, and Pyrometer Indicators E Resistance Thermometry

F Radiation Thermometry

G Humidity Measurements
Thermodynamic Quantities 29010C-2904OS

Pressure Measurements

Technical Contacts:

Bernard E. James W.

Welch Behrens

Tel: 301/975-4826 Tel: 301/975-4857

Mailing Address: A55 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

290 IOC Deadweight Piston Gages

29020C Controlled Clearance Piston Gages

29030C Pressure Gages and Transducers

29035C Mercurial Barometers and Manometers

29040S Special Tests of Pressure Gages

Piston Gages and Pressure Transducers (29010C-29035C)

NIST provides measurement services

for the calibration of piston gages and

transducers operating with gas in the

range of 1.4 kPa to 17 MPa and with

oil in the range of 700 kPa to 400

MPa. Calibrations of customer piston

gages are done in the gage mode by

the cross-floating technique using

NIST working standard piston gages. NIST working standards for use with

gas have been calibrated at the low

end of the pressure range using the

NIST gas thermometer manometer

and at the high end of the range us- ing a controlled-clearance piston gage. The NIST working standards

for oil service have been calibrated

using two controlled-clearance piston gages. Systematic uncertainties associ- ated with such calibrations are shown

in Table 1.

Table 1: Estimated Systematic Uncertainties of Piston

Gage Calibrations in Gage Mode

Type of Instrument Range

Approx. Systematic

Uncertainty

Gas-operated PG 21 kPato 103 kPa ± 22 ppm*

83kPato 1 MPa ± 27 ppm*

690kPato 5 MPa ± 35 ppm*

690kPato 17 MPa ± 41 ppm*

Oil-operated PG 700 kPa to 100 MPa ± 77 ppm

28 MPa to 280 MPa ±73 to ± 150 ppm

40 MPa to 400 MPa ± 186 ppm

* These uncertainties are based on recent evaluations of NIST "transfer" piston gage standards. These estimates are in the process of further eval- uation and may be modified (look for announcements in SP250 Supplements).

Calibrations of transducers are performed in both the gage and absolute modes.

Special Tests of Pressure Gages

(29040S)

Special tests of pressure gages and

other pressure measuring devices may

be performed on request. This in- cludes, as a complement to the special test described in Test No. 30040S

for deadweight piston gages, an absolute mode test in the pressure range

21-103 kPa that can provide systematic uncertainties at a level below

that which is available in Table 1. A

minimum piston gage test will require

data at five or more pressures for each gas desired. Call for further in- formation about this service.

References—Pressure Measurements

Observations of Gas Species and

Mode of Operation Effects on Effective Areas of Gas-Operated Pis- ton Gages, B. E. Welch, R. E. Edsinger, V. E. Bean, and C. D.

Ehrlich, to be published.

47
Practical Uncertainty Limits to the

Mass Determination of a PistonGage Weight, R. S. Davis and

B. E. Welch, J. Res. Natl. Bur.

Stand. (U.S.), 93, No. 4 (July-Aug.

1988). Pressure Metrology: Primary Stan- dard Piston Gages, V. E. Bean,

Proc. Xth Conf. of the Intl. Assoc.

for the Advanc. of High Pressure

Sci. and Tech., Amsterdam (July

1985).

Elastic Distortion of Piston Gages,

J. Lazos-Martinez and V. E. Bean,

Proc. Xth Conf. of the Intl. Assoc.

for the Advanc. of High Pressure

Sci. and Tech., Amsterdam (July

1985). Factors Affecting the Precision of

Gas Operated Piston Gages at the Part Per Million Level, B. E. Welch, L. A. Guildner, and V. E. Bean, Proc. 31st Intl. Instrum. Symp., San Diego, CA, 9 (May

1985).

Note on the Results of the First Phase of an International Comparison in the Pressure Range 20-100

MPa Organized by the High Pres- sure Working Group of the Comite

Consultatif pour la Masse, J. C. Lagras, V. E. Bean, J. Jager, S. L. Lewis, and G. F. Molinar, J. Phys.

E: Sci. Instrum. 18, 361 (1985).

International Comparison in the Pres- sure Range 20-100 MPa Organized

by the High Pressure Working

Group of the Comite Consultatif

pour la Masse, J. C. Legras, V. E. Bean, J. Jager, S. L. Lewis, and

G. F. Molinar, BIPM Internal Technical Report 84/2, Intl. Bur. of Weights and Meas., Paris (1984). Pressure and Temperature Measurements in the Annulus between the

Piston and Cylinder of a Simple

Dead-Weight Piston Gauge, B. E. Welch and V. E. Bean, Rev. Sci. Instrum. 55, 1901 (1984).

Effects of Viscosity, Temperature,

and Rate of Rotation on Pressure Generated by a ControlledClearance Piston Gauge, J. K. N.

Sharma, K. K. Jain, V. E. Bean,

B. E. Welch, and R. J. Lazos, Rev.

Sci. Instrum. 55, 563 (1984).

A Method to Determine the Pressure Dependent Distortion of a Simple

Piston Gage Based on Dimensional

Metrology, B. E. Welch and V. E. Bean, High Pres. Sci. and Tech.,

22, II, 261, C. Homan, R. K.

MacCrone, and E. Whalley, Eds.,

Elsevier Science Publishing Co.,

Inc., New York (1984).

An Intercomparison of Pressure Stan- dards between IMGC and NBS,

J. C. Houck, G. F. Molinar, and

R. Maghenzani, J. Res. Natl. Bur.

Stand. (U.S.), 88, 253 (1983).

An Intercomparison of Pressure Stan- dards between LNE and NBS,

R. G. Driver, J. C. Houck, and

B. E. Welch, J. Res. Natl. Bur.

Stand. (U.S.), 86, No. 3 (May-June

1981).

Absolute High Pressure Measurements, V. E. Bean, High Pressure Science and Technology, B. Vodar

and P. Mardeau, Eds., 231, Pergamon Press, Oxford, England

(1980).

Piston Gages, P. L. M. Heydemann

and B. E. Welch, Chapter 4, Experimental Thermodynamics,

Vol. II, in Experimental Thermodynamics of Non-Reacting Fluids,

B. Le Neindre and B. Vodar, Eds., Part 3, 147, Butterworth and Co.,

London, England (1975).

Reduction of Data for Piston Gage

Measurement, J. L. Cross, Natl. Bur. Stand. (U.S.), Monogr. 65

(1963).

48
30O10C-3O06OS

3.

Low-Pressure, Vacuum, and Leak

Measurements

Technical Contacts:

Richard W.

Hyland

30010C-30021C,

30040C, 30050S

Tel: 301/975-4829

Sharrill Dittmann 30030C-30034C, 30050S

Tel: 301/975-4838

Charles D.

Ehrlich 30060S

Tel: 301/975-4834

Mailing Address: A55 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and Technology, 1-270 at Quince Orchard Rd., A52 Metrology,

Gaithersburg, MD 20899-0001

Test No. Items 30010C Absolute Low-Pressure Transducers

300 lie Up to Two Additional Transducers, Charge for Each

30020C Differential Low-Pressure Transducers Relative

to Vacuum

3002 IC Up to Two Additional Transducers, Charge for Each

30030C Molecular Drag Gages

3003 IC Molecular Drag Gages, Additional Ball or Gas

30032C Ionization Gages, 10"" to 10~' Pa in Nitrogen Gas

30033C Ionization Gages, Additional Filament or Gas,

lO""* to IQ-' Pa

30034C Ionization Gages, 10"^ to lO"" Pa, Nitrogen Gas

30040S Special Tests of Low-Pressure Gages

30050S Special Tests of Vacuum Gages

30060S Special Tests of Leak Artifacts

Low-Pressure Transducers (300 lOC30011C and 30020C-30021C)

Absolute low-pressure gages including capacitance diaphragm gages and

quartz spiral gages are calibrated

against the NIST Ultrasonic Interfer- ometer Manometer. This standard covers a range limited at the low end

by its 10 mPa (lO-* Torr) instability

and extending up to 1600 kPa (1200

Torr). The uncertainty of the standard is 15 ppm of reading plus 10 mPa. This standard is also used for the calibration of low-range differential gages, including ball gages.

Molecular Drag and Ionization Gages

(30030C-30034C)

A standard of the orifice flow type covers the range from 10"' to 10"^

Pa (10-^ to 10"* Torr) for most gases with an uncertainty of 1.5 percent be- tween 10"' and 10~^ Pa increasing to 6 percent at 10~^ Pa. Ionization gages

and molecular drag or spinning rotor gages are accepted for calibration but

all gages must be bakeable to 250 °C

and should be welded to "Conflat"

type flanges. Standard procedure is to calibrate the sensor and electronics as a package although ionization gage

controllers that do not regulate the

emission current or deliberately

change it will not be accepted for

calibration. An extra fee will be

charged for ionization gage calibra- tion below 10"* Pa. For an additional fee NIST will provide tubulated Bayard-Alpert ion- ization gages with tungsten filaments

and 2.75 in. "Conflat" type flanges.

These will be calibrated with the

user's electronics.

Special Tests of Low-Pressure Gages

(30040S) Instruments requiring special calibra- tion procedures or prolonged testing can often be accommodated as a special test. This includes, as a complement to the 29000 series of tests, the

determination of deadweight piston

gage effective area using the NIST

ultrasonic interferometer manometer

as the reference standard. This test can be done in either the gage or ab- solute mode for any inert gas. A minimum piston gage test will require

data for at least one gas in the absolute mode at five or more pressures. For further information contact R. W. Hyland.

49
Special Tests of Vacuum Gages

(30050S) Instruments requiring special calibra- tion procedures or prolonged testing can often be accommodated as a

special test. Consult with S. Dittmann

for further details.

Special Tests of Leak Artifacts

(30060S)

A special-test service is offered for fixed-reservoir helium permeation

leak artifacts in the range 10^ to 10"" mol/s (2x 10-^ to 2X 10-' atm

cc/s at 0 °C). The Report of Test

provides tabulated leak rates at 1 °C

intervals from 0 °C to 50 °C, based on

absolute measurements taken on the

Primary Leak Standard (referenced

to 23 °C), and temperaturedependence measurements taken on a controlled-temperature leak rate comparator system. Typical uncertainties

for the calibrated leaks (3 or) are between 5 and 10 percent. All leak arti- facts submitted for measurement must

have all-metal reservoir and tubing,

be of ultrahigh vacuum-type design,

ending in a standard 2.75" "conflat"

type flange on the vacuum end. The

leak element must be of a sealed glass

design, permeable to helium gas, and

structurally rugged. An easily observable customer identification number

or code must be engraved on the cir- cumference of the 2.75" flange. For

further information contact C. D.

Ehrlich.

Figure 8 summarizes the uncertainties of the NIST low-pressure and vacuum standards. Dashed lines are

target uncertainties expected from new standards under development or improvements to existing standards.

Figure 8. Uncertainties of NIST Low Pressure and

Vacuum Standards

Log Pressure (Torr) -10 -8 -6 -4 -2 0 2 4

1 1 1 1

1 Ultra High

1 1 1 Atmospheric Vacuum Pressure

Ultrasonic

| Manometers

Orifice Flow H \ _ Standards

Present Uncertainties \ Under Development

1 1 1 1 1

\\^

1 1 1

Log Pressure (Pa)

Richard l-lyland (left) and Charles Ehrlich discuss a

typical "reference leak" to be calculated on the NIST

primary leak standard.

50
References—Low-Pressure, Vacuum,

and Leak Measurements

The NBS Ultrasonic Interferometer

Manometer and Studies of GasOperated Piston Gages, C. R.

Tilford and R. W. Hyland, Pro- ceedings of the 11th World Cong,

of the Int. Meas. Conf. (IMEKO),

Metrology, 277, Houston, TX (Oct.

1988).

The NBS Primary High Vacuum

Standard, C. R. Tilford, S. Dittmann, and K. E. McCulloh, J. Vac. Sci. Technol. A6, 2853 (1988).

The Speed of Sound in a Mercury

Ultrasonic Interferometer Manometer, C. R. Tilford, Metrologia 24, 121 (1987).

Low-Range Flowmeters for Use with

Vacuum and Leak Standards, K. E. McCulloh, C. R. Tilford, C. D.

Ehrlich, and F. G. Long, J. Vac.

Sci. Technol., A5, 376 (1987).

Summary Abstract: Present Status of

the Leak Standards Program at the

National Bureau of Standards,

C. D. Ehrlich, J. Vac. Sci. Technol., A5, 125 (1987).

Transfer Leak Studies and Comparisons of Primary Leak Standards at the National Bureau of Standards

and Sandia National Laboratories, R. W. Hyland, C. D. Ehrlich, and

C. R. Tilford, J. Vac. Sci. Technol., A4, 334 (1986).

A Note on Flow Rate and Leak Rate

Units, C. D. Ehrlich, J. Vac. Sci. Technol., A4, 2384 (1986).

Zero Stability and Calibration Results

for a Group of Capacitance

Diaphragm Gages, R. W. Hyland

and C. R. Tilford, J. Vac. Sci. Technol., A3, 1731 (1985).

Zero Stability of Spinning Rotor

Vacuum Gages, K. E. McCulloh,

S. D. Wood, and C. R. Tilford,

J. Vac. Sci. Technol., A4, 1738

(1985).

Long-Term Stability of Two Types

of Hot Cathode Ionization Gages,

S. D. Wood and C. R. Tilford,

J. Vac. Sci. Technol., A3, 542

(1985).

Sensitivity of Hot Cathode Ionization

Gages, C. R. Tilford, J. Vac. Sci. Technol., A3, 546 (1985).

Reliability of High Vacuum Measurements, C. R. Tilford, J. Vac. Sci. Technol., Al(2), 152 (Apr. -June

1983).

Ultrasonic Manometers for Low and

Medium Vacua Under Development at NBS, P. L. M. Heydemann, C. R. Tilford, and R. W.

Hyland, J. Vac. Sci. Technol., 14, 597 (Jan.-Feb. 1977).

51
31010C-31260S

Laboratory Thermometers

Technical Contact:

Jacquelyn A. Wise

Tel: 301/975-4822

Mailing Address: B128 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and Technology, 1-270 at Quince Orchard Rd., A242 Physics,

Gaithersburg, MD 20899-0001

Attn: J. Wise

Test No. Items 31010C Laboratory Thermometers (0 to 150 "C)

(32 to 300 °F)

31020C Laboratory Thermometers (151 to 300 °C)

(301 to 600°F)

31030C Laboratory Thermometers (301 to 538 °C)

(601 to 1000 °F)

31040C Laboratory Thermometers ( - 1 to - 1 10 °C)

(31 to -166°F)

31050C Laboratory Thermometers (Liquid N2)

(-196°C or -320 °F)

31060C Laboratory Thermometers (Liquid O2)

(-183 "C or -297 "F)

31070C Calorimetric Thermometer

31080C Beckmann Thermometer

31100C Quantity Tests of Liquid-in-Glass Thermometers

3 1 1 lOS Special Tests of Thermometers (0 to 1 50 "C)

(32 to 300 °F)

31 120s Special Tests of Thermometers (151 to 300 °C)

(301 to 600 °F)

31130S Special Tests of Thermometers (301 to 538 "C)

(601 to 1000 °F)

31140S Special Tests of Thermometers ( - 1 to 1 10 °C)

(31 to -166 °F)

31150S Special Tests of Thermometers (Liquid N2)

(-196°C or -320 °F)

31160S Special Tests of Thermometers (Liquid O2)

(-183 °C or -297 °F)

3 1200s Preliminary Exam or Ineligible Thermometer

31250S Additional copy of report

31260S Special Thermometry Services, by Prearrangement

Laboratory Thermometers

(31010C-31100C)

This service provides for the calibra- tion of a variety of thermometers

covering the range from — 196 to + 538 °C (-320 to + 1000 °F).

Thermometers belonging to the

large and varied group, which may

be classed as laboratory or "chemical" thermometers, are regularly

accepted. These are of the liquidin-glass type with either solid-stem or enclosed scale. Ordinary household or meteorological thermometers

will not, in general, be accepted unless the scale is graduated on the

glass stem itself and the thermometer

can be readily detached from its mounting for insertion in a testing bath. Every thermometer submitted

must be uniquely identified by a serial number and must pass a preliminary

examination for fineness and uniformity of graduation; for cleanliness of

the mercury and capillary bore; for freedom from moisture, gas bubbles,

and cracks in the glass; for adequacy

or omission of gas filling where

needed; for insufficient annealing; and

for misnumbered graduations. When

these or other serious defects are found, the thermometer is returned

untested. The thermometers to be calibrated are placed in a constant temperature

bath along with the NIST primary

standard—a calibrated platinum resis- tance thermometer. The primary

standard maintains calibrations trace- able to the International Practical

Temperature Scale of 1968 (IPTS68), with an accuracy of ^5 mK at the lower range and ~2 mK at the

higher range. (See Table 2.)

52
31010C-31260S

Table 2: Thermometer Calibration Uncertainties

Type of Thermometer Range

(Total Immersion)

Uncertainty

Mercury-in-glass

(graduations: 0.1-0.2 "C)

Mercury-in-glass

(graduations: 1-2 °C)

Organic liquid-in-glass

0 to 100 °C

0 to 300 "C

300 to 500 °C

-200 to0°C

0.03 to 0.05 °C

0.2 to 0.5 °C

0.5 to 1.0 °C

0.2 to 0.5 "C

Jackie Wise calibrates a group of liquid-in-glass

thermometers using a standard platinum resistance

thermometer

Special Tests of Thermometers

(31110S-31160S)

Special tests may be conducted on

temperature-measuring devices such

as industrial grade platinum resistance

thermometers, digital thermometers,

and thermistors. Laboratory personnel should be contacted before submitting items. Figure 9 summarizes the relative NIST uncertainties for different types

of temperature-measuring instru- ments, including thermometers, ther- mocouples, and pyrometers. See also following sections.

Figure 9. Uncertainties for NIST Calibration of

Temperature Measuring Instruments

(Relative to IPTS-68 and EPT-76)

10'' -

10"

I

10"

•i 10"

10"

10

-IPTS-68- -EPT-76-

0.1 1 .0 10 100

Temperature (K) 1000 10,000

References—Laboratory Thermometers

ASTM Standard El -8 8, Specification

for ASTM Thermometers, Annual

Book of ASTM Standards 14.03, 1, Amer. Soc. for Test, and Matls.,

Phil., PA (1988).

ASTM Standard E77-84, Methods of

Verification and Calibration of

Liquid-in-Glass Thermometers, Annual Book of ASTM Standards

14.03, 59, Amer. Soc. for Test, and

Matls., Phil., PA (1988).

Thermometer Calibration: A Model

for State Calibration Laboratories,

J. A. Wise, R. J. Soulen, Natl. Bur.

Stand. (U.S.), Monogr. 174 (Jan.

1986).

Liquid-in-Glass Thermometry, J. A.

Wise, Natl. Bur. Stand. (U.S.),

Monogr. 150 (Jan. 1976).

53
32010C-32150S

D. Thermocouples, Thermocouple Materials,

and Pyrometer Indicators

Technical Contacts:

George W. Burns

32010C-32101C, 32150S

Tel: 301/975-4817

Margaret G. Scroger 32010C-32101C, 32150S

Tel: 301/975-4818

Jacquelyn A. Wise

32110C-32147C

Tel: 301/975-4822

Mailing Address: B128 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

For 32010C-32101C, 32150S

[Attn: G. Burns or M. Scroger, Bldg. 221, Room B229]

For 32110C-32147C

[Attn: J. Wise, Bldg. 221, Room A242]

Comparison Calibrations, Temperature Measured with Thermocouple:

Test No. Items Temp. Min. Est. TC Range Points Length Temp. Uncert. Type °C mm °C °C

320 IOC S 0-1450 r interv. Table 700 0-1100 0.5 1450 2 32020C R 0-1450 700 0-1100 0.5 1450 2 32030C B 0-1750 1000 0-600 (3jLiV)

600-1100 0.5 1450 2 1750 3 32031C B 800-1750 1000 800-1100 0.5 1450 2 1750 3

Comparison Calibrations, Temperature Measured with Thermocouple:

Test No. ItemsTemp, Min. Est. TC Range Points Length Temp. Uncert. Type °C mm "C °C

32040C

3204 IC

32042C

32043C

32044C

32050C

E

JK

N

T

0-1000

0-760

0-1100

0-1100

0-400

4 to 15 4 to 15 4 to 15 4 to 15 4 to 15700

700

700

700

700

Comparison calibration, 2 point minimum, per point, for all items above

32060C Each additional table of results at 1° intervals, for Type S, R, or B at later date 3206 IC Each additional table of results at 1° intervals, for Type S, R, or B at time of test 32070C Thermocouple materials tested against Pt standard, 4 to 15 points, 700 mm minimum lengths

Calibration at Metal Freezing Points, Minimum

Diameter 0.4 mm, Freezing Point Determination at Au, Ag, 630.74 "C and Zn

32090C S 0-1450 Table, 1° interv. 1000 at freezing 0.2 and equations to points

generate table 0 to 1100 0.3 1450 2

3209 IC Type S, freezing point determination, per point, 2

point minimum

Calibration of Pyrometer Indicators 32100C Portable Potentiometer, first dial or range 32101C Portable Potentiometer, each additional dial or range

54
32010C-32150S

Comparison Calibrations, Temperature Measured with Platinum Resistance Thermometer:

Test No. Items

Comparison Calibration of Thermocouples or Thermocouple Materials Tested against Pt

Thermoelectric Standard, Temperature Measured

with Platinum Resistance Thermometer, Minimum

Length 36 Inches, 2 Point Minimum

321 IOC Range - 110 to +300 °C and Liquid N2 (- 196 °C) or - 166 to 600 °F and Liquid N2 (-320 °F)

32120C 301 to 538 °C or 601 to 1000 °F 32130C Liquid O2 ( - 183 °C) or (-297 °F)

Table at one degree intervals for Type T thermocouple for any of the following options:

(The cost of the table will be in addition to the

calibration per point covered under fee schedule items numbered 321 10C-32130C.)

32141C Option 1: Table from -190 to +300 °C

( — 310 to +572 °F), calibration points at —183,

-110, -50, +100, +200, +300 °C

32142C Option 2: Table from - 190 to + 100 °C

(-310 to +212 °F), calibration points at -183,

-110, -50, +50, +100°C

32143C Option 3: Table from - 1 10 to +300 °C

(— 166 to +572 °F), calibration points at — 110, —50, + 100, +200, +300 °C

32144C Option 4: Table from - 1 10 to + 100 °C

(- 166 to +212 °F), calibration points at - 110, -50, + 50, +100°C

32145C Option 5: Table 0 to 300 °C (32 to 572 °F), calibration points at +100, +200, +300 °C

32146C Option 6: Table from - 1 10 to 0 °C (- 166 to + 32 °F), calibration points at — 1 10, -50 °C. 32147C Option 7: Table from - 190 to 0 °C (-310 to + 32 °F), calibration points at -183, -110, -50 °C

321 SOS Special Tests of Thermocouples and Thermocouple

Materials

Thermocouples, Thermocouple

Materials, and Pyrometer

Indicators (32010C-32147C)

Calibration services for all commonly

used types of thermocouples are pro- vided by NIST from - 196 to 1750 °C depending upon the wire or thermocouple type. The thermocouples are calibrated by one or a combination of three general methods, depending on the thermocouple type,

the temperature range, and the accu- racy required. All three methods

provide traceability to the IPTS-68.

In the first method, thermocouples

are calibrated by comparison with a standard thermocouple maintained at NIST. In the second method, thermocouples are calibrated by comparison

with a standard platinum resistance

thermometer. In the third method,

thermocouples are calibrated at three

defining temperatures on the IPTS

the freezing points of Zn, Ag, and

Au, as well as at 630.74 °C. Below

0 °C the thermocouple calibration is carried out in a cryostat, while above

0 °C stirred liquid baths, metal

freezing-point cells, and electric tube-type furnaces are employed for the calibrations. Vacuum or inert gas furnaces are also available for testing

thermocouples.

Only the bare wires are required to perform the thermocouple calibrations. It is preferable not to send insu- lating and protecting tubes as the rate of breakage of these in shipment is high. If the thermocouple is furnished

mounted (as in a protection tube as- sembly), a nominal charge will be

made for dismantling the mounting

and the various parts will be returned

to the sender without reassembling

them. Thermocouple length requirements listed in the appendix are ex- clusive of lead wire. Lead wire need

not be sent with thermocouples. All

thermocouple calibration data fur- nished in reports will be on the basis of a reference junction temperature

of 0 °C or 32 °F. The calibration re- sults will be given in degrees C or F,

as requested by the customer. The

55
calibration of a thermocouple will not be undertaken if it will likely not

yield the specified accuracy or if it possesses unusual characteristics that would prevent the carrying out of

the calibration or test at a reasonable

cost. Only unused base-metal thermocouples and thermocouple materials

will be accepted for test.

Special Tests of Thermocouples and

Thermocouple Materials (32150S)

For requirements not covered by cal- ibrations described above, special

arrangements may be made by contacting one of the Temperature and

Pressure Division staff members identified at the beginning of this section.

References—Thermocouples

ASTM Standard E220-86, Standard

Method for Calibration of Thermocouples by Comparison Techniques, Annual Book of ASTM

Standards, 14.01, 225, Amer. Soc.

for Test, and Matls., Philadelphia,

PA (1987).

ASTM Standard E230-87, Temperature-Electromotive Force (EMF)

Tables for Thermocouples, Annual

Book of ASTM Standards, 14.01,

242, Amer. Soc. for Test, and

Matls., Philadelphia, PA (1987).

American National Standard,

Temperature Measurement Thermocouples, ANSI-MC96. 1-1982,

Instr. Soc. of Amer., Res. Triangle

Park, NC (1982).

Manual on the Use of Thermocouples

in Temperature Measurement,

ASTM STP 470B, Amer. Soc. for Test, and Matls., Philadelphia, PA

(1981).

Accurate Thermocouple Thermometry, L. A. Guildner and G. W.

Burns, High Temperatures—High

Pressures, 11, 173 (1979).

International Electrotechnical Commission Standard, Thermocouples,

Part I: Reference Tables, lEC Publication 584-1, Intl. Electrotech.

Com., Geneva (1977).

Thermocouple Reference Tables

Based on the IPTS-68, R. L. Powell, W. J. Hall, C. H. Hyink,

Jr., L. L. Sparks, G. W. Burns,

M. G. Scroger, and H. H. Plumb,

Natl. Bur. Stand. (U.S.), Monogr.

125 (1974).

Methods of Testing Thermocouples

and Thermocouple Materials,

W. F. Roeser and S. T. Lonbarger,

Natl. Bur. Stand. (U.S.), Circular

590 (1958).

56
jj^ Resistance Thermometry

Technical Contacts:

William R. Bigge

Tel: 301/975-4823 Gregory F. Strouse

Tel: 301/975-4803

Mailing Address: B128 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, B04

Physics, Gaithersburg, MD 20899-0001

Attn: W. R. Bigge or G. F. Strouse

Test No. Items 33010C Long Stem PRT (-50 °C to +500 or +630 °C)

33020C Long Stem PRT ( - 183 °C to +500 or +630 °C)

33030C Calorimetric Type PRT (-50 to +150 °C)

I 33040C Capsule Type PRT (13 K to 600 K)

33050C Capsule Type PRT ( - 183 °C to +300 °C)

33060S Special Tests of Germanium Resistance

Thermometers (2 to 20 K)

33070C Additional Copy of Table from Results of 33010C-33050C at Time of Test 33080C Additional Copy of Table from Results of 33010C-33050C at Later Date

33090S Minimum Charge for Unsuitable Thermometer

33100S Special Tests of Resistance Thermometers

33110S Special Tests of Thermometric Fixed-Point Devices

33120M Measurement Assurance Program for Temperature

Platinum Resistance Thermometers

(33010C-33050C)

NIST provides calibration services

for standard platinum resistance ther- mometers (SPRTs) from 13.81 to 903 K. Both long-stem and capsuletype SPRTs are calibrated, providing

direct access to the IPTS-68. The

reproducibility of the calibration

measurements of SPRTs is better

than ±0.3 mK and the accuracy of

overall calibration is ± 1 mK. The re- producibility of triple point of water

cells used for calibration of SPRTs is ±50 jiiK or better while that for zinc

and tin freezing-point cells is ±0.1

mK. The precision of comparison cal- ibration of long-stem type SPRTs in terms of the reference standard

SPRTs at the oxygen boiling point

(-183 °C) is better than ±0.1 mK.

The stability of the reference SPRTs

in this temperature range is also about ±0.1 mK. The NIST temperature scale in the range 13 to 90 K is based on stable reference standard

SPRTs of the capsule type and has a precision of about ±0.1 mK down to about 20 K. Below 20 K, the precision degrades to about ±0.2 mK as the SPRTs become less sensitive. To qualify for testing, either

long-stem or capsule platinum resis- tance thermometers must meet two

conditions. They must reasonably be

expected to meet the requirements of

the IPTS-68 for a standard interpolating instrument (i.e., a four lead resis- tor of high-purity platinum hermetically sealed in a protecting tube).

Second, they must be compatible

with the NIST highest-precision cali- bration equipment. It is important

that, insofar as possible, resistance

thermometers be protected from any

mechanical shock that could alter their calibration. To be shipped, the

thermometer must be softly sup- ported within a case but not be free to rattle. This necessitates the use of

packing material that does not be- come compacted. The thermometer

case should in turn be softly packed

inside a shipping container. The

outside shipping container must be

sufficiently rigid and strong that it will not appreciably deform under

the treatment usually given by shippers. Styrofoam is not sufficiently

rigid to be used as an outside container. Thermometers will not be

returned in containers that are

57
obviously unsuitable, such as those

closed by nailing. Suitable containers

will be provided, for a fee, when a thermometer shipping container is not

satisfactory for re-use.

Special Tests of Germanium

Resistance Thermometers and

Thermometric Fixed Point Devices

(33060S, 33100S, and 33110S)

Special tests of various resistance

thermometers and thermometric fixed

point devices may be made by pre- arrangement with the Temperature

and Pressure Division.

Measurement Assurance Program for Temperature (33120M)

The purpose of this MAP service is to assure the accuracy of the calibra- tion of temperature standards (—183

to +630 °C temperature range) made

by participating laboratories when us- ing platinum resistance thermometry.

Special arrangements may be made if participants are interested in only a portion of this temperature range. The MAP transport standard consists of a set of three commercial

glass-sheathed standard-type platinum

resistance thermometers (SPRTs)

packaged in a special shock-proof

shipping container (mechanical shock

or sudden temperature excursions

may result in shifts in calibration).

These SPRTs are used to assess both

the reproducibility and the accuracy

of calibrations performed by the participating laboratory.

MAP participants should use the

techniques described in NBS Monograph 126 or NBS Special Publication 250-22 and the same fixed points

as in the NIST calibrations, or an SPRT previously calibrated by NIST.

In order to achieve high accuracy,

SPRTs used as standards should be of

the matte-finish type to avoid systematic errors arising from light pipe ef- fects in the glass sheath. The participant must have a triple point of water cell and a calibrated resistance

bridge.

After unpacking the transport stan- dard and inspecting the SPRTs for

damage, the participant should measure the resistances of the SPRTs at the triple point of water using the

triple-point cell. A preliminary check

of the resistances at the water triple

point is used as a "go/no go" check

to ensure that the thermometers have

not been damaged in shipment.

These measurements are reported

by telephone to NIST; if the values

are consistent with the data taken by

NIST before shipment, the participant should proceed with further

measurements. Data are taken by

NIST and the participants at the

fixed points defined in the IPTS-68.

NIST provides a worksheet on which

the participant can record the data. The participant then calculates the

thermometer constants from the ex- perimental data, records them, and

prepares tables of resistance versus temperature.

The SPRTs are recalibrated upon

return to NIST and the participant's

data are compared with NIST's cali- brations. NIST provides a plot of the

participating laboratory's temperature

deviation from NIST values and a written analysis of the data, including

any pertinent observations. In a typi- cal transfer, the participant makes

several measurements over a period

of 2 to 3 months. A typical turn- around time from the date NIST re- ceives the participant's data until a

test report is sent to the participant is 3 to 4 weeks.

The best NIST SPRT calibrations

have precisions of about 0. 1 to

0.2 mK. Sources of error that may

contribute to the total uncertainty in- clude changes in the calibration of

the measurement instruments,

changes in the SPRT itself, and uncertainty of the degree of purity of

the materials used as fixed-point

references (e.g., zinc). As a result of

quantifying these sources of error, NIST currently assigns an uncertainty of 1 mK to the values assigned

to the MAP transport standards. A

standards laboratory conscientiously

participating in this MAP and having

suitable equipment should be able to closely approximate this uncertainty.

58
Former participants in the temperature MAP have had uncertainties that ranged from close to 1 mK to hundredths of a kelvin. No rigid recommendations can be

given concerning how often a participant should utilize the temperature

MAP service. Experience has indi- cated that when temperature measurements are in a state of statistical control, using in-house check stan- dards and control charts to monitor

the process, the participant should be

able to go at least 3 years between

transfers from NIST without significantly degrading the confidence in the correctness of the measurements.

References—Resistance Thermometry

Reproducibility of Some Triple Point

of Water Cells, G. T. Furukawa

and W. R. Bigge, Temperature, Its Measurement and Control in Sci- ence and Industry, Vol. 5, 291,

Amer. Inst. Phys., New York, NY

(1982).

Standard Reference Materials:

Application of Some Metal SRM's

as Thermometric Fixed Points,

G. T. Furukawa, J. L. Riddle,

W. R. Bigge, and E. R. Pfeiffer, Natl. Bur. Stand. (U.S.), Spec.

Publ. 260-77 (Aug. 1982).

A Measurement Assurance Pro- gram—Thermometer Calibration,

G. T. Furukawa and W. R. Bigge,

in Testing Laboratory Performance, Evaluation, and Accreditation, Natl. Bur. Stand. (U.S.), Spec.

Publ. 591, 137 (Aug. 1980).

Comparison of Freezing Temperature

of National Bureau of Standards

SRM-740 Zinc Standards, G. T. Furukawa and J. L. Riddle, Comite

Consultatif de Thermometrie, May

9-11, 1978, Sevres, France. The International Practical Temperature Scale of 1968 in the Region

90.188 K to 903.89 K as Maintained at the National Bureau of

Standards, G. T. Furukawa, J. L. Riddle, and W. R. Bigge, J. Res.

Natl. Bur. Stand. (U.S.), 80A, 477

(May-June 1976).

The International Practical Temperature Scale of 1968 in the Region

12.81 K to 90.188 K as Maintained

at the National Bureau of Standards, G. T. Furukawa, J. R.

Riddle, and W. R. Bigge, J. Res.

Natl. Bur. Stand. (U.S.), 80A, 477

(May-June 1973).

Platinum Resistance Thermometry,

J. L. Riddle, G. T. Furukawa, and

H. H. Plumb, Natl. Bur. Stand.

(U.S.), Monogr. 126 (Apr. 1973).

Investigation of Freezing Temperatures of National Bureau of Stan- dards Tin Standards, G. T. Furukawa, J. L. Riddle, and W. R.

Bigge, Vol. 4 of Temperature, Part

I, 247, Instr. Soc. of Amer., Pitts- burgh, PA (1972).

59
35010C-35070S

Radiation Thermometry

Technical Contacts:

Ronald L. William R. Wilkinson Waters

Tel: 301/975-2325 Tel: 301/975-2328

Mailing Address: A221 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 35010C Optical Pyrometers (1 range between 800 to 2400 °C, 4 to 12 points)

35020C Optical Pyrometers (per range in addition up to 4200 °C)

35030C Additional Interpolated Values

35040C Optical Pyrometers (3 or fewer points, 800 to 4200 °C)

35050C Ribbon Filament Lamp (6 to 16 points, 800 to 2300 °C)

35060C Ribbon Filament Lamp (5 or fewer points, 800 to 2300 °C)

35070S Special Tests of Radiation Pyrometers

Optical Pyrometers and Ribbon

Filament Lamps (35010C-35060C)

These calibration services provide ac- cess to the IPTS-68 as realized by

NIST for the temperature range

800 °C to 4200 °C. High-precision

monochromatic visual and automatic

optical pyrometers are calibrated in that temperature range. Uncertainties

in routine testing vary from ±3 °C at 1064 °C, and ±8 °C at 2800 °C, to ±30 °C at 4200 °C. Ribbon filament

lamps are calibrated using the NIST

photoelectric pyrometer, and reports

of brightness temperature at 655 nm

versus direct current are issued. Uncertainties in routine testing vary

from ±0.75 °C at 1064 °C to ±2 °C

at 2300 °C.

The radiation thermometry portion

of IPTS-68 is defined in terms of a

fixed temperature for the freezing

point of gold (1064.43 °C) and the

Planck equation for the radiation of a blackbody source. In practice, temperature scales are realized by constructing a gold point blackbody and

a variable temperature blackbody,

and then measuring spectral radiance

ratio at a red wavelength (approximately 650 nm) in terms of the

Planck equation. Gold point blackbodies are reproducible to ±0.02 °C,

but the temperature assignment of the

freezing point of gold is uncertain by

about ±0.5 °C. The spectral radiance

ratio measurements can be performed

with an uncertainty of 0.2 to 0.3 percent. Higher accuracies than available

in the routine tests described above

can be provided as special tests subject to the IPTS uncertainties noted.

Calibrations at wavelengths other

than 650 nm can be provided in the

wavelength range 250 to 2500 nm

subject to an additional uncertainty

due to the quality of the variable

temperature blackbody.

Special Tests of Radiation Pyrometers

(35070S)

Calibrations at wavelengths other

than 650 nm can be provided in the

wavelength range 250 nm to 2500 nm

subject to an additional uncertainty

due to the quality of the variable

temperature blackbody. Absorbing

glass filters used for range changing

in optical pyrometers can also be cali- brated as special tests.

References—Radiation Thermometry

NBS Measurement Services: Radi- ance Temperature Calibrations,

W. R. Waters, J. H. Walker, and

A. T. Hattenburg, Natl. Bur.

Stand. (U.S.), Spec. Publ. 250-7

(Oct. 1987).

The International Practical Temperature Scale of 1968, Amended Edition of 1975, Metrologia, 12, 7

(1976).

60
35010C-35070S

Corrections in Optical Pyrometry and

Photometry for the Refractive In- dex of Air, W. R. Blevin, Metrologia, 8, 146 (1972).

Vacuum Tungsten Strip Lamps with

Improved Stability as Radiance

Temperature Standards, T. J. Quinn and R. D. Lee, 5th Symposium on Temperature, 395, Instr. Soc. Am., Res. Triangle Park, NC

(1971).

High-Accuracy Spectral Radiance

Calibration of Tungsten-Strip

Lamps, H. J. Kostkowski, D. E. Erminy, and A. E. Hattenburg,

Adv. Geophys. 14, 111 (1970).

The NBS Photoelectric Pyrometer

and Its Use in Realizing the Inter- national Practical Temperature

Scale above 1063 °C, R. D. Lee,

Metrologia, 2, No. 4, 150 (Oct.

1966).

Theory and Methods of Optical Pyrometry, H. J. Kostkowski and

R. D. Lee, Natl. Bur. Stand. (U.S.),

Monogr. 41 (Mar. 1962).

61
36010C-36070S

a Humidity Measurements

Technical Contacts:

Gregory E. Scace

Tel: 301/975-2626

Peter H. Huang

Tel: 301/975-2621

Mailing Address: B312 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, B349

Physics, Gaithersburg, MD 20899-0001

Test No. Items 36010C Dew-Point Hygrometers ( + 25 to - 15 °C)

36020C Dew-Point Hygrometers (-70 to - 15 °C)

36030C Electric Hygrometers

36040C Electrolytic Hygrometers

36050C Aspirated Hygrometers

36060C Pneumatic Bridge Hygrometers

36070S Special Tests of Humidity

Hygrometers (36010C-36060C)

NIST provides calibration services

for a wide variety of humiditymeasuring instruments. Calibrations

are performed by subjecting the in- strument under test to atmospheres of

known moisture content produced by

the NIST two-pressure humidity generator. The instruments and ranges of

calibration are listed below:

A. Dew-Point Hygrometers cali- brated over the dew/frost range

of- 80 to +80 °C. B. Electric Hygrometers classified under this category are sensors which

sorb water vapor as a function of rel- ative humidity; associated with this sorption is a corresponding change in an electric parameter (that is, resis- tance, capacitance). The range of calibration is 3 to 98 percent relative humidity over the temperature

range -55 to +80 °C. C. Psychrometers are a wet-dry

bulb hygrometer (aspirated psy- chrometers). The contact person

should be consulted for the special features of the psychrometer which

are necessary before the instrument can be calibrated at NIST.

D. Electrolytic Hygrometers are devices which electrolyze water into gaseous oxygen and hydrogen by the

application of a voltage in excess of

the thermodynamic decomposition

voltage for water, and then measure

the electrolysis current. The range

of calibration is 1 to 31,000 ppm by

volume.

E. Pneumatic Bridge Hygrometers are instruments which measure

the variation of the pressure drop

across two combinations of nozzles,

operating at critical flow, with a des- iccant between one pair of nozzles. The range of calibration in mixing ratio (gram water vapor/gram dry air)

is 0.0005 to 0.015. Figure 10 illustrates typical NIST

uncertainties for measurement of humidity standards with atmospheric air at atmospheric pressure.

Figure 10. NIST Uncertainties for Measurements of

hiumidity Standards with Atmosptieric Air at Atmosptieric

Temperature

1000

100

r 10

-70

Frost Point, °C

-50 -30

Dew Point, °C

10 10 30 50

"T

Gravimetric

Two-Pressure Generator

0.1

1.0 c:

10

0.001 0.01 0.1 1 Mixing Ratio, g/kg

10 100

100

62
Special Tests of Humidity (36070S)

Tests for response time, hysteresis,

and stability can be provided upon

request.

References—Humidity Measurements

Vapor Pressure Formulation for Ice, A. Wexler, J. Res. Natl. Bur.

Stand. (U.S.), 81 A (Phys. and

Chem.), No. 1, 5 (Jan.-Feb. 1977).

The NBS Two-Pressure Humidity

Generator, Mark 2, S. Hasegawa

and J. W. Little, J. Res. Natl. Bur.

Stand. (U.S.), 81 A (Phys. and

Chem.), No. 1, 81 (Jan.-Feb. 1977).

Vapor Pressure Formulation for Water in Range 0 to 100 "C, A revision, A. Wexler, J. Res. Natl. Bur.

Stand. (U.S.), 80A (Phys. and

Chem.), Nos. 5 and 6, 775 (Sept.-

Dec. 1976).

A Correlation for the Second Inter- action Virial Coefficients and Enhancement Factors for Moist Air, R. W. Hyland, J. Res. Natl. Bur.

Stand. (U.S.), 79A (Phys. and

Chem.), No. 4, 551 (July-Aug.

1975).

The NBS Standard Hygrometer,

A. Wexler and R. W. Hyland,

Natl. Bur. Stand. (U.S.), Monogr.

73 (May 1964).

63
Chapter

A Photometric Measurements B Spectrophotometric Measurements O Radiometric Measurements D Radiometric Standards in the Far

Ultraviolet E Laser Power and Energy
Optical Radiation i\/ieasurements 37010C-37180S

Photometric Measurements

Technical Contact:

Donald A. McSparron

Tel: 301/975-2321

Mailing Address: B306 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

370 IOC Luminous Intensity Standard (100 W Frosted

Tungsten Lamp, 90 candelas)

37020C Luminous Intensity Standard (100 W Frosted

Tungsten Lamp, color temp., 2700 K)

37030C Luminous Intensity Standard (100 W Frosted

Tungsten Lamp, color temp., 2856 K)

37040C Luminous Intensity Standard (500 W Frosted

Tungsten Lamp, 700 candelas)

37050C Luminous Intensity Standard (500 W Frosted

Tungsten Lamp, color temp., 2856 K)

37060C Luminous Intensity Standard (1000 W Frosted

Tungsten Lamp, 1400 candelas)

37070C Luminous Intensity Standard (1000 W Frosted

Tungsten Lamp, color temp., 2856 K)

37080C Luminous Flux Standard (25 W Vacuum Lamp

about 270 lumens)

37090C Luminous Flux Standard (60 W Gas-Filled Lamp

about 870 lumens)

37100C Luminous Flux Standard (100 W Gas-Filled Lamp

about 1600 lumens)

371 IOC Luminous Flux Standard (200 W Gas-Filled Lamp

about 3300 lumens)

37120C Luminous Flux Standard (500 W Gas-Filled Lamp

about 10,000 lumens)

37130C Luminous Flux Standard (Miniature Lamps 7 sizes 6 to 400 lumens)

37 HOC Airway Beacon Lamps for Color Temperature

(500 W, 1 point in range, 2000-3000 K)

37150C Each additional color temp.

37160C Color temperature equation (4 points and

interpolation equation)

37170C Opal Glass Luminous Directional Transmittance

Standards

371 808 Special Photometric Tests

65

General Information

Calibration services in this area pro- vide access to the photometric scales realized and maintained at NIST.

Lamp standards of luminous intensity,

luminous flux, and color temperature

as described below are calibrated on

a routine basis. Luminous Intensity Standards

(37010C-37070C)

Luminous intensity standard lamps

supplied by NIST [100-W (90-140

cd), 500-W (approximately 700 cd)

and 1000-W (approximately 1400 cd)

tungsten filament lamps with C-13B

filaments in inside-frosted bulbs and

having medium bipost bases] are cali- brated at either a set current or a

specified color temperature in the
range 2700 to 3000 K. Approximate

3-sigma uncertainties are 1 percent

relative to the SI unit of luminous in- tensity and 0.8 percent relative to NIST standards.

Luminous Flux Standards

(37080C-37130C)

Luminous flux standards—geometrically total Vacuum tungsten lamps of 25 W and

60-, 100-, 200-, and 500-W gas filled tungsten lamps that are submitted by

customers are calibrated. Lamps

must be base-up burning and rated

at 120 V. Approximate 3-sigma uncertainties are 1.4 percent relative to SI units and 1.2 percent relative to NIST standards. Luminous flux stan- dards for miniature lamps producing

6 to 400 Im are calibrated with uncertainties of about 2 percent.

Airway Beacon Lamps

(37140C-37160C)

Color temperature standard lamps

supplied by NIST (airway beacon

500-W medium bipost lamps) are cali- brated for color temperature in the

range 2000 to 3000 K with 3-sigma

uncertainties ranging from 10 to 15 degrees.

Opal Glass Luminous Directional

Transmittance Standards (37170C)

Flashed opal glasses, 51 mmx51 mm,

are calibrated for luminous directional transmittance (exitant lumi- nance per incident illuminance). The

glasses are masked with a diaphragm

limiting the useful area to a circle 1.9 cm in diameter.

Special Tests of Photometric Devices

(37180S)

Lamp standards of luminous intensity can be calibrated at any color temperature in the range 2000 K to 3200 K. Photometric values can be

computed for special sources measured spectrally on the Facility for Automatic Spectral Calibrations

(FASCAL). See test 39060S for details.

Reference—Photometric Measurements

NBS Measurement Services: Photometric Calibrations, R. L. Booker

and D. A. McSparron, Natl. Bur.

Stand. (U.S.), Spec. Publ. 250-15

(Oct. 1987).

66
3801OC-381OOS

Spectrophotometric Measurements

Technical Contact:

p. Yvonne Barnes

Tel: 301/975-2345

Mailing Address: B306 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 38010C Spectral Transmittance Filters (Cobalt Blue Glass)

38020C Spectral Transmittance Filters (Copper Green Glass)

38030C Spectral Transmittance Filters (Carbon Yellow Glass)

38040C Spectral Transmittance Filters (Selenium Orange

Glass)

38050C Wavelength Standards (Holmium Oxide Glass) 38060S Special Tests of Spectral Transmittance and

Reflectance 38070M Measurement Assurance Program for Retroreflectance—Complete Package

38071M Retroreflectance MAP—Sheeting Standards or

Prismatic Standard with Colored Filters 38072M Retroreflectance MAP—Sheeting Standards and

Prismatic Standard without Colored Filters 38073M Retroreflectance MAP—Sheeting Standards or

Prismatic Standard without Colored Filters 38074M Retroreflectance MAP—Colored Filters Only

38080M Measurement Assurance Program for Transmittance

38090S Special Tests of X-Ray and Photographic Step

Tablets

381(X)S Special Tests of Microcopy Resolution Test Charts

Spectral Transmittance Filters (38010C-38040C)

NIST supplies standards of spectral

transmittance for checking the photometric scale of spectrophotometers.

These are either 30-mm polished glass

disks or 51 -mm polished glass squares, 2 to 3 mm thick, designated

as cobalt blue, copper green, carbon

yellow, and selenium orange. Infor- mation provided to the user includes

values of transmittance at 25 °C at 10 nm intervals from 380 to 770 nm, the

estimated uncertainty of each value,

and data as to the effect of temperature change on transmittance at each

wavelength.

Wavelength Standards (38050C)

Holmium oxide glass standards are

also supplied for checking the ultravi- olet and visible wavelength calibra- tions of recording spectrophotometers

having a bandpass less than 2 nm. These are made of polished Corning

3130 glass, 51x51 mm, 2.5 mm thick. A table of wavelengths of minimum

transmittance is provided in the re- port to the user.

Special Tests of Spectral Transmittance and Reflectance (38060S)

Measurements of spectral transmit- tance can be made for the wavelength region 190 to 2500 nm. Measurements of absolute spectral re- flectance factors and of spectral specular reflectance can be made for the

wavelength region 250 to 2500 nm. However, arrangements for these

measurements on submitted speci- mens must be made before shipment.

The decision as to whether or not to perform the measurements and selec- tion of the instruments to be used will

rest with NIST. Specimens not ac- cepted for measurement will be re- turned. Accuracy and precision

estimates will be given. Estimates will be dependent upon the optical characteristics of the submitted specimens.

67
Measurement Assurance Programs for Retroreflectance (38070M-38074M)

These Measurement Assurance Pro- grams (MAP's) verify, within certain

Hmits, how well a laboratory can measure coefficient of luminous intensity. The verification is accomplished

by means of a MAP package. The

MAP package contains two white

bead sheeting retroreflectors, one col- orless prismatic retroreflector, and

seven colored glass filters. The ele- ments in this package are measured

by NIST, then by the participating

laboratory, and finally by NIST.

Quality control procedures are maintained by using NIST master stan- dards.

The use of three retroreflectors enables determination of how vvell the

participant can measure coefficient of

luminous intensity for white or colorless samples of three kinds of geometries. The luminous transmittance of

the seven colored glass filters can be

used as a diagnostic tool to check

measurements of coefficient of lumi- nous intensity of colored retroreflectors. This is accomplished by

checking the conformance of the

source-receiver combination to CIE

Illuminant A and photopic response,

respectively.

The coefficient of luminous intensity of each of the bead sheeting stan- dards is measured at six combinations

of observation and entrance angles.

The coefficient of luminous intensity

of the prismatic retroreflector is measured at 18 combinations of entrance and observation angles. The luminous

transmittance of the filters is pro- vided only for the spectral conditions

of source and receiver specified

above.

A general testing laboratory will probably need the service utilizing

the complete MAP package. However, some laboratories may be specialized. For this reason, we list five options that offer not only the complete package, but also some selected

components. These options are the

following:

A. Complete MAP package;

B. Sheeting standards or prismatic standard with colored filters; C. Sheeting standards or prismatic standard without colored fil- ters;D. Sheeting standards and prismatic standard without colored fil- ters; and

E. Colored filters only.

Measurement of even the complete

MAP package achieves only part of

the goal of a MAP service. To fully

benefit from the MAP procedure, we

suggest that the participant have on hand several check standards to be

measured while also measuring the

MAP package. These check stan- dards can then be measured periodically to determine any gross error in measurement procedure, and a control chart can be constructed. A control chart is a plot of measurement

result versus time, and normally the

measurement process is considered to be under control if measurements fall within ±3 standard deviations from

the mean. For retroreflectance measurements where geometric errors are

large, the standard deviation obtained

after changing geometrical parameters may be large compared with that obtained from repeated measurements

without changing the apparatus.

Thus, the total variation for a given

instrument can be obtained only by

repetition over a period of time and

realignment of the experimental apparatus.

The uncertainties of retroreflec- tometer measurements have three

sources: uncertainties associated with

values assigned by NIST to the MAP

package, participant uncertainties,

and uncertainties due to environment

and sample interaction. Repeated

measurements without changing the

apparatus show that the NIST ran- dom error is small relative to the sys- tematic errors. A large fraction of the

latter arises when the retroreflector is rearranged and realigned for making

measurements with different measure- ment parameters.

68
Measurement Assurance Program for Transmittance (38080M)

The Transmittance Measurement Assurance Program (MAP) provides a means for a laboratory to assess the

accuracy of its spectral transmittance

measurement capabilities. A laboratory that participates in this program

will be sent a package of trans- mittance filters, which have been

measured at NIST. These are to be

measured by the laboratory on its spectrophotometer(s) and returned,

together with the measurement results, to NIST. NIST will then re- measure the filters and send a final analysis of the result to the participating laboratory. The range of filter measurements provided in the MAP

package permits an evaluation of the

accuracy of a laboratory's spectral

transmission measurements and will often reveal the cause of any systematic errors that exist. The contents of the MAP package

include seven neutral density filters with nominal transmittances ranging

from 0.92 to 0.001. The filters are

available in three sizes. The filter holders are 51x51 mm, 51x38 mm,

or standard cuvette. In addition, the

package contains one didymium glass

filter or cuvette-sized holmium oxide

solution that is to be used for wavelength scale calibration. Several

wavelengths of transmittance minima

and points of inflection have been

measured by NIST for the didymium

filter. These wavelengths have been

shown to be stable over long periods

of time; therefore, these didymium fil- ters are not normally measured by

NIST with every use of the MAP

package. The didymium filter is useful for triangular bandpasses between

1.5 and 10.5 nm. The holmium oxide

solution has been certified at several

wavelengths for bandpasses up to 3.0 nm.

It is strongly suggested that the

participating laboratory acquire a set of check standards similar to the

NIST filters for maintaining a control

chart and measurement assurance.

Special Tests of X-Ray and

Photographic Step Tablets (38090S)

Special tests for visual transmission of

density ranges from 0 to 4 (by inte- grating sphere or by opal glass dif- fuser) and reflection optical density can be performed by prior arrange- ment. Tablets submitted must be free of scratches, fingerprints, abrasions,

and foreign matter and must have

steps of uniform density. The visual transmission density is measured in accordance with ANSI Standard

PH2.19/ISO 5/2-1986. The visual re- flection density of 45V0° is measured

in accordance with ANSI Standard

PH2.17/ISO 5/4-1985.

Special Tests of Microcopy Resolution Test Charts (38100S) Test charts conforming to ISO Stan- dard 3334, NMA Standard MS 104- 1972, and MIL-M-9868D, can be

tested by special arrangement.

References—Spectrophotometric

Measurements

National Scales of Spectrometry in the U.S., J. J. Hsia, Advances in Standards and Methodology in Spectrophotometry 1987, Elsevier

Science Publishers, B. V., Amsterdam, pp. 99-109 (1987).

NBS Measurement Services: Spectral

Reflectance, V. R. Weidner and

J. J. Hsia, Nafl. Bur. Stand. (U.S.),

Spec. Publ. 250-8 (July 1987).

NBS Measurement Services: Regular

Spectral Transmittance, K. L. Eckerle, J. J. Hsia, K. D. Mielenz,

and V. R. Weidner, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-6

(July 1987).

White Opal Glass Diffuse Spectral

Reflectance Standards for the Visi- ble Spectrum (SRM's 2015 and

2016), V. R. Weidner, Natl. Bur.

Stand. (U.S.), Spec. Publ. 260-82

(1983).

Extension of a Reference Spectrophotometer into the Near Infrared,

K. L. Eckerle, V. R. Weidner, J. J. Hsia, and Z. W. Chao, Natl. Bur. Stand. (U.S.), Tech. Note 1175

(Apr. 1983).

69
Measurement Assurance Program

Transmittance Standards for Spectrophotometric Linearity Testing:

Preparation and Calibration, K. L. Eckerle, V. R. Weidner, J. J. Hsia,

and K. Kafadar, J. Res. Natl. Bur.

Stand. (U.S.), 88(1), 25 (1983).

Second-Surface Mirror Standards of

Spectral Specular Reflectance

(SRM's 2023, 2024, 2025), J. C. Richmond, J. J. Hsia, V. R. Weidner, and D. B. Wilmering, Natl. Bur. Stand. (U.S.), Spec. Publ.

260-79 (Oct. 1982).

Proposed Standards for the NBS

Retroreflectance MAP, K. L. Eckerle and J. J. Hsia, Color Res. and Appl., 7(3), 235 (1982).

NBS 45 "/Normal Reflectometer for Absolute Reflectance Factors, J. J. Hsia and V. R. Weidner, Metrologia, 17, 97 (1981).

NBS Specular Reflectometer—Spectrophotometer, V. R. Weidner and

J. J. Hsia, Appl. Opt., 19, 1268

(Apr. 1980).

New Reference Retroreflectometer,

K. L. Eckerle, J. J. Hsia, V. R. Weidner, and W. H. Venable, Jr., Appl. Opt., 19(8), 1253 (1980).

Photometry and Colorimetry of

Retroreflection: State-of-Measurement Accuracy Report, K. L. Eckerle, Natl. Bur. Stand. (U.S.),

Tech. Note 1125 (July 1980).

Inverse-Fourth Apparatus for Photometric Calibrations, D. A. Swyt

and J. G. LaRock, Rev. Sci. lu- strum., 49(8), 1083 (Aug. 1978).

Basic Considerations of Densitometer

Adjustment and Calibration, R. E. Swing, Natl. Bur. Stand. (U.S.),

NBSIR 75-682 (Feb. 1975).

Establishing a Scale of DirectionalHemispherical Reflectance Factor

1 : The Van den Akker Method,

W. H. Venable, Jr., J. J. Hsia, and

V. R. Weidner, J. Res. Natl. Bur.

Stand. (U.S.), 82, 1, 29 (July-Aug.

1977).

New Reference Spectrophotometer,

K. D. Mielenz, K. L. Eckerle,

R. P. Madden, and J. Reader,

Appl. Opt., 12, 7, 1630 (July 1973).

The Optics of Densitometry, R. E. Swing, Opt. Eng., 12, 6, 185

(Nov.-Dec. 1973).

Basic Considerations of Densitometer

Adjustment and Calibration, R. E. Swing, Natl. Bur. Stand. (U.S.),

Report 10970 (Dec. 1972).

Permanence of Glass Standards of

Spectral Transmittance, K. S. Gibson and M. A. Belknap, J. Res.

Natl. Bur. Stand. (U.S.), 44, 463

(May 1950).

70
39010C-39080S

Radiometric Measurements

Technical Contacts:

John K. Jackson 39010C-39060S

Tel: 301/975-2330

Jeanne M.

Houston 39070C

Tel: 301/975-2327

Douglas B. Thomas

39080S

Tel:301/975-2323

Mailing Address: A221 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 39010C Spectral Radiance Ribbon Filament Lamps (225 to 2400 nm)

39020C Spectral Radiance Ribbon Filament Lamps (225 to 800 nm)

39030C Spectral Radiance Ribbon Filament Lamps (650 to 2400 nm)

39040C Spectral Irradiance Quartz-Halogen Lamps (250 to 1600 nm)

39045C Spectral Irradiance Quartz-Halogen Lamps (250 to 2400 nm)

39050C Spectral Irradiance Deuterium Lamps (200 to 350 nm)

39060S Special Tests of Radiometric Sources 39070C Photodiode Spectral Response Rental Package

39080S Special Tests of Radiometric Detectors

Spectral Radiance Ribbon Filament

Lamps (39010C-39030C)

These spectral radiance standards are supplied by NIST. Tungsten, ribbon

filament lamps (30A/T24/13) are pro- vided as lamp standards of spectral

radiance. The lamps are calibrated at 34 wavelengths from 225 to 2400 nm,

with a target area 0.6 mm wide by

0.8 mm high. Radiance temperature

ranges from 2650 K at 225 nm, and

2475 K at 650 nm to 1610 K at 2400

nm, with corresponding uncertainties

of 2, 0.6, and 0.4 percent. For spectral radiance lamps, errors are stated

as the quadrature sum of individual

uncertainties at the three standard deviation level. See also related tests 40010C-40040S, next section. Figure 1 1 summarizes the measure- ment uncertainty for NIST spectral

radiance calibrations.

Figure 1 1. Uncertainties for NIST Spectral Radiance

Calibrations

500

a> 200 -

100 -

0.4 0.6 1 2

Wavelength in Micrometers

Spectral Irradiance Lamps

(39040C-39050C)

These spectral irradiance standards

are supplied by NIST. Lamp stan- dards of spectral irradiance are pro- vided in two forms. Tungsten

filament, 1000-watt quartz halogen

type FEL lamps are calibrated at 31 wavelengths in the range 250 to 2400 nm. At the working distance of 50 cm, the lamps produce 0.2 W/cm^ at 250 nm, 220 W/cm' at 900 nm, 115

W/cm^ at 1600 nm, and 40 W/cm^ at 2400 nm, with corresponding uncertainties of 2.2, 1.3, 1.9, and 6.5 percent. For spectral irradiance lamps,

errors are stated as the quadrature sum of individual uncertainties at the

three standard deviation level. Deuterium lamp standards of spectral ir- radiance are also provided and are

calibrated at 16 wavelengths from

200 to 350 nm. At the working

71
39010C-39080S

distance of 50 cm, the spectral irradi- ance produced by the lamp ranges

from about 0.5 W/cm^ at 200 nm and

0.3 W/cm' at 250 nm to 0.07 W/cm'

at 350 nm. The deuterium lamps are intended primarily for the spectral re- gion 200 to 250 nm. The approximate

uncertainty relative to SI units is 7.5 percent at 200 nm and 5 percent at 250 nm. The approximate uncertainty

in relative spectral distribution is 3 percent. It is strongly recommended

that the deuterium standards be compared to an FEL tungsten standard over the range 250 to 300 nm each

time the deuterium lamp is lighted to take advantage of the accuracy of the

relative spectral distribution. Figure 12 summarizes the measure- ment uncertainty for NIST spectral

irradiance calibrations of type FEL

lamps.

Figure 12. Uncertainties for NIST Spectral Irradiance

Calibrations of Type FEL Lamps

0.1 0.2 0.4 0.6 1 2 4 6 Wavelength in Micrometers

Special Tests of Radiometric Sources

(39060S)

Spectroradiometric source calibra- tions are performed on the Facility

for Automatic Spectral Calibrations

(FASCAL). This instrument has the

capability of performing spectral radi- ance measurements from 200 to 2400

nm, radiance temperatures from

1050 K to 2700 K, and adjustable

spectral bandpass down to 0.1 nm.

Spectral irradiance measurement capability from 200 to 2400 nm at flux levels down to 0.1 W/cm^ is also

available. For both spectral radiance

and irradiance measurements a wide

variety of sources and measurement

geometries are possible. Special tests utilizing the capabilities of FASCAL

are occasionally performed depending on the availability of the equipment

and associated personnel.

Photodiode Spectral Response Rental

Package (39070C)

Photodiode response packages can be

rented from NIST. Absolute spectral

responsivity calibrations can be obtained by leasing one of the NIST

Detector Response Transfer and In- tercomparison Packages. This is a well-characterized radiometer that

utilizes a silicon photodiode as the

detector element. Its calibration is re- ported in units of A/W at a number

of wavelengths in the 250 to 1064 nm

range. A precision aperture is pro- vided for calibrations in units of A

cm^/W. The duration of the lease is sufficient to enable the transfer of the

calibration to a laboratory's own in- house standards, and the performance

of specific diagnostic tests to check

the laboratory's capability to perform

spectral response transfer measurements. At present, the calibration is based on the self-calibrated silicon photodiode technique and electrical substitution radiometry using cw laser

lines and several atomic emission

lines as monochromatic radiation sources for the characterization measurements. The absolute spectral re- sponse is reported at 10 nm intervals

from 250 to 960 nm, and at two dis- crete wavelengths outside this range

(1014 and 1064 nm). The estimated

uncertainty ranges from 1 to 6 percent, depending on the wavelength

and the particular radiometers. The

radiometers cover a range of detector current from 10 ' to 10"'* A. This

corresponds to a radiant power range

of about 1 nw to 1 mw.

72
Special Tests of Radiometric Detectors (39080S)

Special tests of radiometric detectors

generally used in the ultraviolet, visi- ble, and infrared regions of the spec- trum can be performed. Types of

detectors that may be submitted for

special test include but are not limited to (1) radiometric quality solidstate photodiodes, (2) 100 percent

quantum efficient radiometers, (3) electrically calibrated pyroelectric ra- diometers, and (4) electrically cali- brated radiometers. Examples of

detector characteristics that can be

determined in a special test include

spectral response (A/W), quantum ef- ficiency (electrons/photon), linearity,

and uniformity (over surface area).

Since special tests of this type are unique, details of the tests should be

discussed with J. Houston or D. Thomas prior to submitting a for- mal request.

References—Radiometric Measurements

NBS Measurement Services: The

NBS Photodetector Spectral Response Calibration Transfer Pro- gram, E. F. Zalewski, Natl. Bur.

Stand. (U.S.), Spec. Publ. 250-17

(1988).

NBS Measurement Services: Spectral

Irradiance Calibrations, J. H.

Walker, R. D. Saunders, J. K.

Jackson, and D. A. McSparron,

Natl. Bur. Stand. (U.S.), Spec.

Publ. 250-20 (Sept. 1987).

NBS Measurement Services: Spectral

Radiance Calibrations, J. H.

Walker, R. D. Saunders, and A. T. Hattenburg, Natl. Bur. Stand.

(U.S.), Spec. Publ. 250-1 (Jan.

1987).

Silicon Photodiode Device with

100% External Quantum Effi- ciency, E. F. Zalewski and C. R. Duda, Appl. Opt., 22, 2867 (1983).

Silicon Photodiode Absolute Spectral

Response—Self-Calibration Using a Filtered Tungsten Source, C. G.

Hughes III, Appl. Opt., 21, 2129

(1982).

Silicon Photodiode Absolute Spectral

Response Self-Calibration, E. F. Zalewski and J. Geist, Appl. Opt.,

19, 1214 (1980).

Spectral Response Self-Calibration

and Interpolation of Silicon Photodiodes, J. Geist, E. F. Zalewski,

and A. R. Schaefer, Appl. Opt. 20,

3795 (1980).

Spectral Irradiance Standard for the

Ultraviolet: The Deuterium Lamp,

R. D. Saunders, W. R. Ott, and

J. M. Bridges, Appl. Opt. 17, 593

(1978).

The 1973 NBS Scale of Spectral Irra- diance, R. D. Saunders and J. B. Shumaker, Natl. Bur. Stand. (U.S.),

Tech. Note 594-13 (1977).

Spectral Radiometry: A New Approach Based on Electro-Optics,

J. Geist, M. A. Lind, A. R.

Schaefer, and E. F. Zalewski, Natl. Bur. Stand. (U.S.), Tech. Note 954

(1977).

Fundamental Principles of Absolute

Radiometry and the Philosophy of

This NBS Program (1968 to 1971),

J. Geist, Natl. Bur. Stand. (U.S.),

Tech. Note 594-1 (1972).

High-Accuracy Spectral Radiance

Calibration of Tungsten-Strip

Lamps, H. J. Kostkowski, D. E. Erminy, and A. T. Hattenburg,

Adv. Geophys., 14, 111 (1970).

73
40010C-40040S

^\ Radiometric Standards in the Far Ultraviolet

m^m D.l Standard Sources

Technical Contacts:

\

,1 1^

Mervin Bridges

Tel: 301/975-3228

Mailing Address: A167 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 400 IOC Spectral Irradiance Standard, Argon Mini-Arc

(140 to 330 nm)

40020C Spectral Radiance Standard, Argon Mini-Arc

(115 to 330 nm)

40030C Spectral Irradiance Standard, Deuterium Arc Lamp

(165 to 200 nm)

40040S Special Tests of Radiometric Devices in the Near and

Vacuum Ultraviolet

Source Calibrations in the Ultraviolet

(40010C-40040S)

NIST maintains a collection of sec- ondary standard sources such as ar- gon maxi-arcs, argon mini-arcs, and

deuterium arc lamps in the near and vacuum ultraviolet radiometric stan- dards program to provide calibrations

for user-supplied sources. The cali- brations of these sources are traceable

to a hydrogen arc whose radiance is calculable and which NIST maintains

as a primary standard. The collection

also includes tungsten strip lamps and

tungsten halogen lamps whose cali- brations are based on a blackbody

rather than a hydrogen arc. Customer-supplied sources are calibrated

in both radiance and irradiance by

comparing them with NIST sec- ondary standards.

Argon arcs are used to calibrate

other sources in the wavelength

range 115 nm to 330 nm for radiance

and 140 nm to 330 nm for irradiance.

The lower wavelength limit is deter- mined in radiance by the cutoff of the

magnesium fluoride windows used in the arcs and in irradiance by the de- crease in signal produced by the addition of a diffuser. Deuterium arc lamps are used in the range 165 nm

to 200 nm, with the low wavelength

cutoff due to the onset of blended

molecular lines. The high wavelength

limit is the starting point of the range

of another calibration group at NIST.

(See tests 39010C-39050C, previous

section.) The tungsten lamps are used

at 250 nm and above, since their sig- nals are too weak at shorter wavelengths. It should be noted that the

wavelength range of the NIST arcs

partially overlaps the range of tungsten lamps, thus providing an independent check on calibrations. An argon mini-arc lamp supplied

by the customer is calibrated for spectral irradiance at 10-nm intervals

in the wavelength region 140 to 300 nm. Absolute values are obtained by

comparison of the radiative output

with laboratory standards of both

spectral irradiance and spectral radi- ance. The spectral irradiance measurement is made at a distance of 50

cm from the field stop. Uncertainties

are estimated to be less than ±10

percent in the wavelength region 140

to 200 nm and within ±5 percent in the wavelength region 200 to 330 nm. A measurement of the spectral trans- mission of the lamp window is in- cluded in order that the calibration

be independent of possible window

deterioration or damage. The uncertainties given here and below are taken to be two standard deviations

(2cr), i.e., as having a confidence limit of about 95 percent.

The spectral radiance of argon

mini-arc radiation sources is deter- mined to within an uncertainty of less than 7 percent over the wavelength

range 140-330 nm and 20 percent over

the wavelength range 115 to 140 nm.

74
The calibrated area of the 4-mm di- ameter radiation source is the central 0.3-mm diameter region. Typical val- ues of the spectral radiance are: at 250 nm, L^ = 30 mW cm"^ nm"' sr~'; and at 150 nm, Lx = 3 mW cm~^ nm"'

sr '. The transmission of the demountable lamp window and that of an additional MgF2 window are determined individually so that the user may check periodically for possible

long-term variations. The deuterium arc lamp is cali- brated at 10 wavelengths from 165 to 200 nm, at a distance of 50 cm, at a spectral irradiance of about 0.5 W/

cm^ at 165 nm, 0.3 W/cm' at 170 nm,

and 0.5 W/cm^ at 200 nm. The ap- proximate uncertainty relative to SI

units is estimated to be less than 10 percent. The lamp is normally supplied by NIST and requires 300 mA

at about 100 V.

References—Source Calibrations in the Ultraviolet

Radiometric Calibrations of Portable

Sources in the Vacuum Ultraviolet,

J. Z. Klose, J. M. Bridges, and

W. R. Ott, J. Res. Natl. Bur. Stand.

(U.S.), 93, 21 (1988).

NBS Measurement Services: Radiometric Standards in the Vacuum

Ultraviolet, J. Z. Klose, J. M.

Bridges, and W. R. Ott, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-3

(June 1987).

Radiance of a Pt/Cr-Ne Hollow

Cathode Spectral Line Source,

J. Z. Klose and J. M. Bridges,

Appl. Opt., 26, 5202 (1987).

VUV Spectral Irradiance Calibrations: Method and Applications,

W. R. Ott, J. M. Bridges, and J. Z. Klose, Opt. Lett., 5, 225 (1980).

Spectral Irradiance Standard for the

Ultraviolet: The Deuterium Lamp,

R. D. Saunders, W. R. Ott, and

J. M. Bridges, Appl. Opt., 17, 593

(1978).

Spectral Radiance Calibrations be- tween 165-300 nm: An Interlaboratory Comparison, J. M. Bridges,

W. R. Ott, E. Pitz, A. Schultz,

D. Einfield, and D. Stuck, Appl.

Opt., 16, 1788 (1977).

VUV Radiometry, 3: The Argon

Mini-Arc as a New Secondary

Standard of Spectral Radiance,

J. M. Bridges and W. R. Ott, Appl.

Opt., 16, 367 (1977).

NBS UV Radiometric Standards,

W. R. Ott, Natl. Bur. Stand. (U.S.),

Spec. Publ. 456, 107 (1976).

75
40510C-40599S

^\ Radiometric Standards in the Far Ultraviolet

m^m D.2 Standard Detectors in the

Far Ultraviolet

Technical Contacts:

L. Randall Nils Swanson

Canfield Tel: 301/975-3729

Tel: 301/975-3728

Mailing Address: A251 Physics, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 405 IOC Detector Standard, Windowless Photodiode

(5 to 122 nm)

405 lie Recalibration of Detector Standard (5 to 122 nm)

40520C Detector Standard, Windowless Photodiode

(18 to 122 nm)

4052 IC Recalibration of Detector Standard (18 to 122 nm)

40530C Detector Standard, Windowless Photodiode

(52 to 122 nm)

4053 IC Recalibration of Detector Standard (52 to 122 nm)

40540C Uncalibrated Windowless Photodiode

40560C Detector Standard, Windowed Photodiode

(116 to 254 nm)

4056 IC Recalibration of Detector Standard (1 16 to 254 nm)

40599S Special Tests on Detectors from the Near Ultraviolet (320 nm) to the Soft X-Ray Region (5 nm)

Detector Calibrations in the Ultraviolet (40510C-40599S)

Calibrated transfer standard detectors

for the far ultraviolet are available

from NIST to cover the spectral re- gion 5 to 254 nm. Users are furnished

with the quantum efficiency as a function of wavelength, with quantum efficiency defined as the number

of photoelectrons per incident photon. Two detector types are available

to cover this range: (1) a windowless

photodiode with an AI2O3 photocathode for the wavelength region

5 to 122 nm; and (2) a MgFjwindowed photodiode with a semitransparent CsTe photocathode for the wavelength region 116 to 254 nm. The detectors have been extensively

studied regarding radiometrically important parameters such as photocathode spatial uniformity and

temporal stability of photoemission.

The probable errors in the measured quantum efficiencies are 8 to 15 percent in the 5- to 122-nm windowless photodiode region and 6 to 10 percent in the 116- to 254-nm windowed photodiode region. Probable

error means that there is a probability

of 0.5 that the true quantum effi- ciency values lie within the stated er- ror range about the values measured.

Apparatus at the NIST electron storage ring facility, SURF-II, is used by Randall Canfield to calibrate pfiotodiodes.

All calibrations are based on the

rare gas ionization chamber as an absolute detector. In the windowless re- gion 5 to 92 nm, working standards

are calibrated directly against such a reference, while at longer wavelengths it is necessary to transfer the

calibration derived from the ioniza- tion chamber at shorter wavelengths

with the use of a special uniformly

76
40510C-40599S

"gray" thermopile. The shortest portion of the windowless region in- volves the use of a beamline at the

NIST electron storage ring facility,

SURF-II, while the calibrations

above 50 nm are conducted using

plasma light sources in a laboratory

environment.

Outgoing detectors are calibrated

by direct intercomparison with pre- calibrated working standards that are

periodically recalibrated. Windowless

AI2O3 photodiodes are fabricated in- house; the windowed CsTe photodiodes are procured commercially and

tested for stability and spatial homogeneity. Only those photodiodes

meeting stringent NIST quality specifications are selected as transfer stan- dards. The calibration costs include

the cost of the detector and screening

services unless a recalibration of pre- viously used detectors is requested.

Special detectors that do not lend

themselves to convenient on-site cross-calibration may also be cali- brated at NIST if the detectors merit

radiometric application and if the

NIST calibration facilities are suitable and available for the particular

device.

References—Detector Calibrations in the Ultraviolet

Far Ultraviolet Detector Standards,

L. R. Canfield and N. Swanson,

J. Res. Natl. Bur. Stand. (U.S.), 92,

97 (1987).

NBS Measurement Services: Far Ultraviolet Detector Standards, L. R. Canfield and N. Swanson, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-

2 (June 1987).

Time Response of NBS Windowless

XUV Radiometric Transfer Standards, E. B. Saloman, Appl. Opt.

14, 1764 (1975).

77
42110C-42180S

Laser Power and Energy

Technical Contacts:

Thomas R. Scott Aaron A. Sanders Kathy Hillen

Tel: 303/497-3651 Tel: 303/497-5341 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M. C. 724.02, National Institute of

Standards and Technology, 325 Broadway, Boulder,

CO 80303-3328

Test No. Items

42 HOC Laser Power and Energy Meter Calibrations 42120M Laser Power and Energy Measurement Assurance Program (MAP)

42130C Optical Fiber Power Meter Calibrations 42140M Optical Fiber Power Meter Measurement Assurance Program (MAP)

42150M Low-Level Laser Measurement Assurance Program

(MAP)

42160C Pulsed 10.6-fi,m Laser Calibrations 421 70S Special Tests for Laser Power and Energy Meters, by

Prearrangement

421 SOS Special Tests for Optical Fiber Power Meters, by

Prearrangement

Laser Power and Energy—General

Information

The National Institute of Standards

and Technology develops and maintains the U.S. national standards for the measurement of laser power and

energy. These standards are realized

in the form of several types of iso- peribol (constant temperature environment) calorimeters. The calorimeters compare absorbed laser radiation

to an equivalent quantity of electrical energy. Well-characterized transfer standards (calibrated against the

primary standards) are also maintained as laboratory standards for cal- ibrations and for use in Measurement

Assurance Program (MAP) intercomparisons. The primary standards and

secondary transfer standards are used

in specially designed calibration sys- tems that allow various power and

energy meters to be compared to the

standards. Table 3 summarizes the

measurement capabilities of the primary standard measurement systems

and lists typical calibration uncertainties.

Table 3: Primary Standard Measurement Capabilities

Primary Typical

Standard Wavelength Range Power Range Uncertainty

C-series 488.0, 514.5 nm 1 jaW - 1 W ±0.5-1.0%

632.8 nm 1 jaW - 20 mW ±0.5-1.0%

830 nm 100 /xW- 20 mW ±0.5-1.0%

1.06 jLim 1 mW - 1

W

±0.5-1.0%

1.32 /xm 100 jaW - 100 mW ±0.5-1.0%

1.53 jam 100 /xW - 1 mW ±0.5-1.0%

Q-series 1.06 jam (Q-switched) < 1 10 mJ/pulse ±1.1-1.9%

Kl -series 10.6 jam 1 W - 300 W ±1.6-2.5%

K2-series 10.6 jam 40 mW- 40 W ±2.5-3.5%

Laser Power and Energy Meter

Calibration (42110C)

Within the ranges listed in Table 3, NIST can perform calibrations at the

power or energy and wavelength

specified by the owner. The instru- ment is sent to NIST where it is then

compared to the appropriate primary

reference calorimeter using a cali- brated beamsplitter measurement sys- tem. Normally, no adjustments are made to the test instrument. At the

completion of the calibration measurements, the instrument and a cali- bration report are sent to the owner. The calibration report summarizes

the results of the measurements and

provides a detailed listing of the asso- ciated measurement uncertainties. These calibration measurements are accomplished using a calibrated

beamsplitter arrangement in which

both the standard and the test meter

are exposed to the laser beam

78
42110C-42180S

simultaneously. All the significant

parameters (e.g., electrical calibration

coefficient, absorptivity, window

transmission) for each of the standard

calorimeters used in these measure- ments have been evaluated for each

laser wavelength used. Based on first principles of thermodynamics and lin- ear system analysis, the characteristic

voltage response of the standard

isoperibol calorimeters can be correlated to the quantity of energy ab- sorbed. Because the reference

calorimeters measure energy, laser

stability is not required when cali- brating other energy detectors. However, when calibrating power meters,

either a stable laser is used or else the

voltage of the test meter is integrated

to give an energy measurement. The

data acquisition and analysis for these

systems are computer controlled.

The laser sources used for these

calibration measurements with the

primary standards consists of the fol- lowing types: (1) helium-neon (632.8

nm), (2) helium-neon (1.53 jLtm), (3) argon ion (488.0 & 514.5 nm), (4) Nd:YAG (1.064 ju,m, cw &

Q-switched), (5) Nd:YAG (1.32 /xm),

(6) diode laser (830 nm), and (7) car- bon dioxide (10.6 ju-m).

Laser Power and Energy Measurement

Assurance Programs (42120M)

The Measurement Assurance Pro- gram (MAP) service is available at the wavelengths and powers listed in Table 3. The laser MAP intercomparisons are implemented by means

of transfer standards which have been

evaluated and characterized relative to the national primary standards.

The measurement system and primary

standards discussed above are used to calibrate the transfer standards for the intercomparisons. The characteristics of these transfer standards are well understood, and their associated

accuracies do not differ significantly

from those associated with direct

comparisons to the primary stan- dards. For a specified wavelength

and power or energy, the appropriate

transfer standard is selected and sent from NIST to the MAP participant.

The participant calibrates the NIST

transfer standard using his measure- ment system and then returns both

his data and the transfer standard to NIST. Before and after the NIST

transfer standard is shipped to the

participant, NIST performs calibra- tion measurements on the detector to provide continuity during the inter- comparison process. At the completion of the intercomparison sequence,

NIST evaluates the participant's measurement results relative to the NIST

calibration results on this same meter. A MAP intercomparison report is then submitted to the participant

summarizing the intercomparison and

listing the associated measurement

uncertainties.

Optical Fiber Power Meter

Calibrations (42130C)

Optical fiber power meters are cali- brated using an automated calibration

system in which the test meter and

the laboratory standard are alter- nately exposed to a stable laser source. Table 4 summarizes the current capabilities of this system. The

laboratory standard used for these

measurements is an electrically cali- brated pyroelectric radiometer

(ECPR), which has been calibrated

against the C-series primary standard

calorimeter. Various laser sources are used to provide collimated beams ap- proximately 3 to 4 mm in diameter

for the optical power meter calibrations.

Table 4: Measurement Capabilities

Laboratory Typical

Standard Wavelength Window Power Range Uncertainties ECPR 850 nm 100 jxW ±0.5-1.0%

ECPR 1300 nm 100 jLtW ±0.5-1.0%

ECPR 1550 nm 100 ixW ±0.5-1.0%

79
42110C-42180S

, Optical Fiber Power Meter

Measurement Assurance Program

(MAP) (42140M)

NIST maintains a set of calibrated

transfer standards that are available

for MAP intercomparisons of optical

fiber power meters. These transfer standards are calibrated using the optical fiber power meter calibration

system discussed above at the wavelengths listed in table 4.

Low-Level Laser Measurement

Assurance Program (MAP) (42150M)

NIST has designed and constructed

special silicon and germanium diode

detectors to measure pulse energy

and peak power of low-level,

1.064-jLtm laser pulses of about 10- to 100-ns duration. These diode detectors have been evaluated for spatial

uniformity, bandwidth, and linearity,

and are used as transfer standards for intercomparison measurements. The

output response of each detector has

been calibrated against a transfer standard, which, in turn, has been

calibrated against the C-series

calorimeter. The system for calibrat- ing these transfer standards uses a cw Nd:YAG laser beam, which is acousto-optically modulated to pro- duce short, well-defined pulses. The

beam intensity is attenuated to low

levels using a multiple reflection precision wedge beamsplitter. The transfer standards are available for intercomparisons at the levels listed in table 5.

Table 5: Low-Level MAP Transfer Standards

Transfer Standard Energy/Power Range Typical Uncertainty

Silicon PIN 10" ''-lO"" J/cmVpulse ±8-10%

Germanium PIN lO^^-lO"'^ J/cmVpulse ±15%

Silicon APD IQ-^-lQ-'* W/cm^ (peak) ±9-12%

Pulsed 10.6-j(xm Laser Calibrations

(42160C)

NIST can perform responsivity and

energy calibrations on instruments designed to measure pulsed laser radiation at a wavelength of 10.6 jam. For

these measurements a transfer stan- dard (calibrated against the K-series

calorimeters) is used in a beamsplitter

arrangement in which a transversely

excited atmospheric pressure (TEA)

CO2 laser is used as the radiation source. The TEA laser, surrounded

by a shielded aluminum enclosure, is composed of both a high-pressure cell containing the gain medium (mixture

of carbon dioxide, helium, and nitro- gen) and a low-pressure gain cell also containing the same gain medium.

The low-pressure cell causes the laser to operate at a single longitudinal

mode (SLM). To determine responsivity, the output voltage waveform

of the instrument being calibrated is acquired with a transient digitizer and

numerically integrated with a computer. The voltage integral is then di- vided by the incident energy as measured by the transfer standard

and beamsplitter system. At the completion of the responsivity or energy

measurements, a calibration report is sent, along with the detector, to the owner. Table 6 summarizes the capability of this pulsed measurement sys- tem.

Table 6: Pulsed CO2 Calibrations

Pulse Typical Measurement Width Pulse Energy Uncertainty

Responsivity 200 ns 5-60 mJ/pulse (SLM TEMoo) ±5-15%

Energy 200 ns 5-300 mJ/pulse (multi-spatial mode) ±5%

80
Special Tests for Laser Power and

Energy Meters, by Prearrangement

(42170S) Laser calibrations or measurements

not specifically mentioned above may

be arranged by contacting NIST and

discussing the particular requirements

with the appropriate NIST personnel.

Special-test measurements could in- clude, for example, calibrations at wavelengths or power levels not

listed above or other unique measure- ments such as impulse response or

linearity measurements. Low-level

laser calibrations are also included in

this category. All these measurements

must be prearranged with NIST.

Special Tests for Optical Fiber Power

Meters, by Prearrangement (42180S)

The special tests in this category in- clude optical fiber power meter measurements not listed above. For

example, this category would be used

for power meters using fiber connectors or meters that have small-area

detectors. All these special-test

measurements must be prearranged

with NIST.

References—Laser Power and Energy

NBS Laser Power and Energy Measurements, T. R. Scott, Proc. SPIE

O-E LASE '88, Optoelectronics

and Laser Applications in Science

and Engineering (1988).

A System for Measuring Energy and

Peak Power of Low-Level 1.064- jum Laser Pulses, A. A. Sanders

and A. L. Rasmussen, Natl. Bur. Stand. (U.S.), Tech. Note 1058

(Oct. 1982).

Documentation of the NBS C, K, and

Q Laser Calibration Systems,

W. E. Case, Natl. Bur. Stand.

(U.S.), NBSIR 82-1676 (Sept.

1982).

A System for Measuring the Characteristics of High Peak Power Detectors of Pulsed CO2 Radiation,

P. A. Simpson, Natl. Bur. Stand.

(U.S.), Tech. Note 1023 (Sept.

1980).

Quality Assurance Program for the

NBS, C, K, and Q Laser Calibration Systems, W. E. Case, Natl. Bur. Stand. (U.S.), Int. Report,

NBSIR 79-1619 (Aug. 1979).

A System for Calibrating Laser Power Meters for the Range

5-1000 W., E. D. West and L. B. Schmidt, Natl. Bur. Stand. (U.S.),

Tech. Note 685 (May 1977).

An NBS Measurement Assurance

Program, A. A. Sanders and A. R. Cook, Proc. Electro-Optics Laser

Conference (1976).

Absolute Reference Calorimeter for Measuring High-Power Laser

Pulses, D. L. Franzen and L. B. Schmidt, Appl. Opt. 15, 3115 (Dec.

1976).

A Calorimeter for High-Power CW

Lasers, R. L. Smith, T. W. Russell,

W. E. Case, and A. L. Rasmussen,

IEEE Trans. Instr. Meas., Vol. IM21, No. 4 (Nov. 1972).

A Reference Calorimeter for Laser

Energy Measurement, E. D. West,

W. E. Case, A. L. Rasmussen, and

L. B. Schmidt, J. Res. Natl. Bur.

Stand. (U.S.), 76A, No. 1, 13 (Jan.-

Feb. 1972).

Data Analysis for Isoperibol Laser

Calorimetry, E. D. West, Natl. Bur. Stand. (U.S.), Tech. Note 396

(Feb. 1971).

Theory of Isoperibol Calorimetry for Laser Power and Energy Measurement, E. D. West and K. L. Churney, J. Appl. Phys. 41, No. 6, 2705

(May 1970).

References—Optical Fiber Power

Meter Measurements

Calibrated Optical Fiber Power

Meters: Errors Due to Variations

in Connectors, Xiaoyu Li and

R. L. Gallawa, Fiber & Integrated

Optics, Vol. 7 (to be published in 1988).

Calibration of Optical Fiber Power

Meters: The Effect of Connectors,

R. L. Gallawa and Xiaoyu Li,

Appl. Opt. 26, 1170 (Apr. 1987).

Optical Fiber Power Meters: A

Round Robin Test of Uncertainty, R. L. Gallawa and Shao Yang,

Appl. Opt. 25, 1066 (Apr. 1986).

8 1
Chapter

A Radioactivity Sources B Neutron Sources and Neutron

Dosimetry

C Dosimetry of X Rays, Gamma Rays,

and Electrons D Dosimetry for High-Dose Applications
I Ionizing Radiation H^easurements 43010C-43090S

Jacqueline M. Pamela A. Hodge Cassandra Beck

Calhoun 43030C-43050C Administrative

Tel: 301/975-5538 Tel: 301/975-5544 and Logistics

Tel: 301/975-5531

Mailing Address: CI 14 Radiation Physics, National Insti- tute of Standards and Technology, Gaithersburg, MD

20899-0001

Test No. Items 43010C Gamma-Ray-Emitting Radionuclides in Solution (Half Lives Greater Than 1 5 Days)

43020C Gamma-Ray-Emitting Radionuclides in Solution (Half Lives Less Than 15 Days)

43030C Alpha-Particle-Emitting Solid Sources, NIST 2 -rra proportional counter 43040C Alpha-Particle-Emitting Solid Sources, NIST 0.8 Tra defmed-solid-angle counter 43050S Alpha-Particle-Emitting Solid Sources, using both

counting systems

43060S Special Tests of Beta-Particle-Emitting Solution Sources—Liquid Scintillation Counting

43070S Special Tests of Beta-Particle-Emitting Solution

Sources, Other Techniques

43090S Special Tests of Alpha-Particle-Emitting Solid Sources

Radioactivity Sources—General

Information (43010C-43090S)

The National Institute of Standards

and Technology offers calibration

services for over 50 radionuclides.

Calibrations are provided that meet

the requirements of industry, re- search, environmental monitoring,

and the life sciences. Radioactivity

calibration services are available for alpha-particle solid sources, betaparticle solutions, and gamma-ray

solutions.

In order to offer such a broad

range of services, NIST must place

stringent limitations on the physical

and chemical form and activity range

of sources that can be accepted. To

ensure that these specifications are understood, it is essential that there

be good communication between the technical user and the technical contact at NIST. When planning to have

a source calibrated, the user should

discuss the following points with the

NIST contact: A. Type of calibration: Often, more than one type of calibration is available for a given source. A

cobalt-60 source, for example, may be

calibrated in terms of total activity or gamma-ray-emission rate. (Inquiries

regarding the calibration of radioactive sources for exposure rate should

be directed to the Dosimetry Group.

See tests 47010C to 47040S.) The re- quired total uncertainty in the cali- bration should also be discussed.

B. General packaging and shipping requirements: Two general re- quirements apply to all sources submitted for calibration: (1) all shipments must conform to applicable

Nuclear Regulatory Commission

(NRC) and Department of Transportation (DOT) packaging and

transport; and (2) source descriptions,

including approximate activity, must

be provided in advance. The NIST

Health Physics Group must approve

the receipt of radioactive material,

and sources may be refused if the

necessary information is not available. C. Reports of Calibration: A Report of Calibration is sent upon completion of a radioactivity calibration

service. If the user has particular re- quirements for documentation of the

calibration, these should be discussed

with the technical contact at NIST

before the services are performed.

D. Sample Preparation, Packaging, and Shipping: All samples submitted for calibration must be

chemically and physically stable. The

83
chemical form of solutions suggested

for beta-particle emitters and gammaray emitters are described later in this document. A special lot of borosili- cate-glass ampoules must be used for gamma-ray emitters. Empty ampoules

are provided for this purpose. The

volume of material in the ampoule

should be 5.0±0.2 mL.

Packaging for all sources must be

in compliance with DOT and NRC

regulations. Copies of regulations

may be obtained from Operations Division, Office of Hazardous Materials,

Department of Transportation, Washington, DC 20950. Postal regulations

prohibit the mailing of radioactive

materials that require a caution label under DOT regulations.

Alpha-particle solid sources must

be supplied in special source nolders

designed so that the active area is not touched by any material. For sources

to be measured in the 2 77a counter

(calibration 43030C), the diameter of

the source must be less than 10 cm

and that of the active surface less than 9 cm. For the 0.8 va counter

(calibration 43040C), the maximum

diameter is 1.6 cm.

All sources arriving at NIST are checked by the Health Physics

Group for radiation level and source

integrity. Sources should be shipped

to the attention of the technical contact at NIST, addressed, for example,

as follows:

National Institute of Standards

and Technology

Attn: Jacqueline M. Calhoun

Health Physics (Radioactivity

Group)

Quince Orchard and Clopper

Roads

Gaithersburg, MD 20899-0001

Gamma-Ray-Emitting Solution

Sources (43010C-43020C)

Tables 7 and 8 list 39 radionuclide so- lutions that may be calibrated in the

NIST "47r"y ionization chamber. The

sources must be submitted flamesealed in the special ampoules pro- vided by NIST. The operation of

this type of chamber is described in NCRP Report 58, A Handbook of

Radioactivity Measurements Procedures, Section 4.4 "Ionization Chambers," and in NBS SP 250-10,

Radioactivity Calibrations with the

"477" Gamma Ionization Chamber

and other Radioactivity Calibration

Capabilities (see references).

Table 7: Specifications for Calibration of Gamma-Ray

Emitting Solutions Which Are Submitted for Calibration

Radionuclides Having Half Lives Greater Than 1 5 Days

Suggested Chemical Form"' Nominal "3or" Uncer. Limits

of lonization- Activity

Radio- Chamber Range^'

nuclide Calibration"" (MBq) Carrier Solution (%)

"Na 1.6 0.4-40 NaCl 1 M HCl

0.8 0.4-40 ScCh 1 MHCl

^•Cr 1.0 2-60 CrCh 0.5 M HCl

-"*Mn 1.2 2-60 MnClz 1 MHCl

"Co 0.8 2-60 C0CI2 1 MHCl

'"Fe 1.4 0.4-40 FeClj 1 MHCl

^°Co 0.8 0.4-40 C0CI2 1 MHCl

"Se 2.4 2-60 H2Se63 1 M HNO3

2.0 2-60 SrCb 1 M HCl

SSy 0.7 0.4-40 YCI3 1 MHCl

'O'Cd- 109m^g(d)

1.7 2-60 CdCl2 1.3 MHCl*

-"°Ag 0.9 0.4-40 AgNOs 1 M HNO3

"^Sn- 3.0 2-60 SnCh or 4 MHCl

SnCU

•"Ba 1.5 2-60 BaCh 1 MHCl

'^^Cs 1.0 2-60 cscr 1 M HCl

'"Cs- 1.5 2-60 CsCl 1 MHCl

'^'Ce 1.0 2-60 CeCl3 1 M HCl

•^'Ce 2.0 2-60 CeCl, 1 M HCl

•"Eu 1.6 0.4-40 EUCI3 1 M HCl

0.8 0.4-40 EuCb 4M HCl

1.5 2-60 EUCI3 4 MHCl

.69Yb 2.5 2-60 YbCl3 0.1 M HCl*

2.3 2-60 KAu(CN)4 lOgL-'KCN*

lOgL"' KCl*

1.4 2-60 Hg(N03)2 0.1 M HNO3

The total estimated uncertainty will depend upon the activity level and chemical form. The source activity should be in the indicated range when it arrives

at NIST. The calibration scheduling must be coordinated with the NIST technical contact. This information is based in large part on the NIST Standard Refer- ence Materials for these radionuclides. For those radionuclides marked

with an asterisk, the carrier should be discussed with the NIST technical contact. '""The calibration for ""Cd — '"''"Ag is in terms of gamma-ray-emission

rate rather than activity.

84
43010C-43090S

Table 8: Specifications for Calibration of Gamma-Ray

Solution Sources

Radionuclides Having Half Lives Less Than 15 Days

Radionuclide

Nominal "3o-" Uncer. Limits

of lonization- Chamber

Calibration*"*

Suggested Chemical Form''

Activity

Range""

(MBq) Carrier Solution (%)

2*Na 0.8 0.4 -40 NaCl 1 M HCl

«^Ga 1.4 0.4 -40 GaCh 2 M HCl

''Mo-'''"Tc 1.6 2 -60 Molybdate 4 M HNO3

99171^^ 1.5 2 -60 No carrier Saline added/

pertechnetate

"'In 1.3 2 -60 InCl2 3 M HCl

123j 1.5 2 -60 KI, NajSOj 0.01 M LiOH*

1.3 2 -60 KI, NazSOj 0.01 M LiOH*

•«Ba-'«La 3.4 0.4 -40 Ba(N03)2, 1 M HCl

La(N03)3

2.4 2 -60 Hg(N03)2 O.IMHNO3

1.3 2 -60 KAu(CN)4 lOgL-'KCl,

lOgL-'KCN

201^2 1.9 2 -60 T(N03)3 0.9 M HNO3

203pb 1.7 2 -60 PbCl2 0.5 M HCl

The total estimated uncertainty will depend upon the activity level and chemical form.

'''' The source activity should be in the indicated range when it arrives at NIST. The calibration scheduling must be coordinated with the NIST

technical contact.

'^^ This information is based in large part on the NIST Standard Refer- ence Materials for these radionuclides. For those radionuclides marked

with an asterisk, the carrier should be discussed with the NIST technical

contact.

Alpha-Particle-Emitting Solid Sources

(43030C-43050C)

Alpha-particle sources may be cali- brated using the National Institute of

Standards and Technology 2 ira proportional counter, or the National Institute of Standards and Technology

0.8 na defmed-solid-angle counter. The former calibration is in terms of

alpha-particle-emission rate into 2 wa

steradians, while the latter is in terms

of total activity. A more detailed

comparison of these counting systems

is given in NCRP Report 58 (Section

3.7) and in NBS SP 250-5, AlphaParticle Calibrations. Backscattering

corrections for a variety of source- mount materials are discussed in the

references given. The source thick- ness must be such that more than 99.5

percent of the emitted alpha particles

have an energy greater than 400 keV.

Further specifications for these cali- bration services are given in Table 9. Test 43050C includes calibration of

the same source using both counting

systems.

Table 9: Specifications for Calibrations Using the 2 ttu Proportional Counter and the 0.8 ira Defined Solid

Angle Counter

Calibration 43030C

Calibration 43040C

Counting System

Sources Calibrated For:

NIST 2 TTa proportional counter

NIST 0.8 77-a defmed-solidangle-counter

Alpha-particleemission

rate into 2 na

steradians either above 400 KeV or

extrapolated to zero KeV (in s-')

Total activity

(in Bq)

Nominal Uncertainty (

So-) 1.5 percent

Activity Range ~(0.4- 10'')s" Maximum Source Diameter

10 cm (9 cm

active surface)

1.5 percent

_(40_10'*)s-'

1.6 cm

The total estimated uncertainty will depend upon the activity level and

source geometry.

Special Tests of Beta-Particle-Emitting

Solution Sources (43060S and 43070S)

Beta-particle-emitting solutions that conform to the physical, chemical,

and activity specifications for measurement are assayed by liquid-scintil- lation counting. The specifications are shown in Table 10. Solutions should

be approximately 5 mL in volume

and flame-sealed in glass vials or ampoules. The suggested radioactivity

concentration range is 20 to 2000

kBq/g.

85
43010C-43090S

Table 10: Specifications for Special Tests of

Beta-Particle-Emitting Solution Sources

Suggested Chemical Composition'

Radio- Nominal

nuclide Uncertainty"''

(%)

Carrier Solution

1.0 H2O H2O

''*C 1.5 Na2C03 0.001 M NaOH

32p(c) 1.0 H3PO4 0.0034 M H3PO4

33p 1.0 H3PO4 0.0034 M H3PO4

1.0 Li2S04 0.1 MHCl

^''Cl 2.0 NaCl H2O

''St 1.0 SrCl2 1 MHCl

1.0 SrCh/YCb 1 MHCl

90y 1.0 YCI3 1 MHCl

1.0 PmCh 1 M HCl

2C14-pj 2.0 T1(N03)3 1 M HNO3

The total estimated uncertainty will depend upon the activity level and chemical form. The chemical composition is critical for these calibratiors c-nd should be discussed before sending the source. This calibration includes a half-life fit to determine the "P impurity.

No examination is made for beta- particle-emitting impurities, except in the case of phosphorus-32 where a

half-life fit is made. The sources will be examined for gamma-ray emitting

impurities.

Measurement of beta-particleemitting solutions by techniques other

than liquid-scintillation may be made

by special arrangement.

Special Alpha-Particle-Emitting Solid

Sources (43090S)

Special arrangements may be made

for measurements of solid alphaparticle-emitting sources with emission rates exceeding 1.1 X lO'* Bq.

References—Radioactivity Sources

NBS Measurement Services: Radioactivity Calibrations with the "47r" Gamma Ionization Chamber and

Other Radioactivity Calibration

Capabilities, J. M. Calhoun, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-

10 (Oct. 1987).

NBS Measurement Services: AlphaParticle Calibrations, J. M. R. Hutchinson, Natl. Bur. Stand.

(U.S.), Spec. Publ. 250-5 (July

1987).

NCRP Report 58, A Handbook of

Radioactivity Measurements Procedures, Section 3.7 —Alpha-Particle

Counting, W. B. Mann, Ed., Natl. Council Rad. Protect, and Meas.,

Washington, DC (1985).

Study of the Scattering Correction

for Thick Uranium-Oxide and

Other a-Particle Sources,

I: Theoretical, L. L. Lucas and

J. M. R. Hutchinson, Int. J. Appl.

Radiat. Isotopes, 27, 35 (1976).

Study of the Scattering Correction

for Thick Uranium-Oxide and

Other a-Particle Sources,

II: Experimental, J. M. R. Hutchinson, L. L. Lucas, and P. A.

Mullen, Int. J. Appl. Radiat. Iso- topes, 27, 43 (1976).

Backscattering of Alpha Particles

from Thick Metal Backings as a Function of Atomic Weight,

J. M. R. Hutchinson, C. R. Naas,

D. H. Walker, and W. B. Mann,

Int. J. Appl. Radiat. Isotopes, 19, 517 (1968).

An Experimental Study of the

Backscattering of 5.3 MeV-Alpha

Particles from Platinum and Monel

Metal, D. H. Walker, Int. J. Appl.

Radiat. Isotopes, 16, 183 (1965).

86
44010C-44100S

Neutron Sources and Neutron Dosimetry

Technical Contacts:

E. Dale Robert B. George P. Edward W.

McGarry Schwartz Lamaze Boswell 44010C, 44020C, 44060C, 44100S 44070C-44090C, 44010C-44060C

44100S Tel: 301/975-6203 4410DS Tel: 301/975-6207

Tel: 301/975-6205 Tel: 301/975-6202

Mailing Address: A135 Reactor, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

440 IOC Radioactive Neutron Sources (10^ to 10* n/s)

44020C Radioactive Neutron Sources (10* to 10'° n/s)

44060C Personnel Protection Instrumentation, Californium Source Bare and Moderated

44070C Activation Detector Dosimetry, Thermal Neutrons 44080C Activation Detector Dosimetry, Californium Fission Neutrons 44090C Activation Detector Dosimetry, ^^^U Cavity Fission Source

44100S Special Tests of Neutron Sources and Dosimeters

Radioactive Neutron Sources

(44010C-44020C)

NIST provides calibration services

for radioactive neutron sources with

emission rates from 5 X 10^ to 1 X 10'° neutrons/second. Emission rates are determined by the Manganous Sulfate

Bath Method to an accuracy of about

1.2 percent (one sigma) depending

upon the details of source encapsulation. Sources to be calibrated are compared in the bath to the emission

rate of NIST- 1, the national standard

Ra-Be photoneutron source. The

emission rate of NIST-1 (1.2 X 10^ n/s

in January 1989) has an assigned uncertainty of ±0.85 percent (one

sigma).

Ed Boswell operates the manipulator arm from operator's side of shield wall. The MfiSOa bath facility can be

seen in background through shield window.

Personnel Protection Instrumentations

(44060C)

Neutron personnel instruments, both

passive (e.g., dosimeters) and active

(e.g., remmeters) are calibrated on

the basis of a certified free-field doseequivalent or dose equivalent rate. Two ^"Cf source-driven neutron

fields are available on a routine basis for this purpose: bare source and

heavy-water moderated ""Cf fission neutron sources. Thermal and filtered neutron beams are also available for special requirements under Test No.

44100S. For both bare and moderated

"'Cf source exposures, maximum

dose-equivalent rates are about 2 rem/h. The calibration uncertainty is in the range of ±5 percent (Icr), in- cluding a ±4 percent component for the dose equivalent conversion factor.

87
44010C-44100S

Activation Detector Dosimetry

(44070C-44090C)

Passive neutron detectors, generally

activation foils, can be irradiated to a

certified neutron fluence (or average

fluence rate) in fission spectrum or Maxwellian thermal neutron fields. Irradiation parameters are given in Table 11.

Table 11: Irradiation Parameters for Fission Spectrum

and Maxwellian Thermal Neutron Fields

Neutron Field

Typical

Maximum

Fluence

(n/s)

Typical

Maximum

Fluence Rate

(n/cm^)

Accuracy

do-) (%)

^"Cf Fission Source 5X10'^ 2X10' <±1.3(^^

^'^U Cavity Fission

Source*^' 5X10'= 4x10'° <±2.3^'

Thermal Neutrons

Beam*'-"' ixio'^ 8x10' ±2.5

Isotropic >1X10'^ 2x10" ±2.5

Threshold detectors only. Maximum size of detector disks- 12.7 mm

dia. X about 3 mm thick. Radial gradient of fluence: about 20 percent

center-to-edge. Uncertainty includes neutron scattering corrections. Maxwellian distribution corresponding to a temperature of about 40 °C.

Special Tests of Neutron Sources and

Dosimeters (44100S)

Other tests of dosimetry instrumentation may be undertaken by special ar- rangement with the Ionizing

Radiation Division. In particular for personnel protection instruments, a thermal beam can provide dose

equivalent rates of up to approximately 1 rem/h across a 30-cm di- ameter circle, and three monoenergetic filtered neutron beams may

be used to investigate neutron re- sponse as a function of energy. Energies and typical dose equivalent rates for the filtered beams are 2 keV

(8 mrem/h), 24 keV (15 mrem/h),

and 144 keV (120 mrem/h).

References—Radioactive Neutron

Sources

NBS Measurement Services: Neutron

Source Strength Calibrations at NBS by the Manganese Sulfate

Bath Method, E. D. McGarry and

E. W. Boswell, Natl. Bur. Stand.

(U.S.), Spec. Publ. 250-18

(Mar. 1988).

Neutron Source Calibrations at NBS

for Calibration Checks of Neutron

Radiation Instruments, V. Spiegel,

Jr., Proc. of Symp. on Meas. for the Safe Use of Radiation, Natl. Bur. Stand. (U.S.), Spec. Publ. 456,

87 (Nov. 1976).

Calibration of Thermal Neutron Absorption in Cylindrical and Spherical Neutron Sources, V. Spiegel,

Jr., and W. M. Murphey, Metrologia, 7, 34 (Jan. 1971).

The Correction Factor for Fast Neutron Reactions on Sulphur and

Oxygen in the Manganous-SulfateBath Calibration of Neutron

Sources, W. M. Murphey, Nucl.

Instrum. Methods, 37, 13 (1965).

Absolute Calibration of the National

Bureau of Standards Photoneutron

Source: III. Absorption in a Heavy

Water Solution of Manganous Sulfate, R. H. Noyce, E. R. Mosburg,

Jr., S. B. Garfinkel, and R. S. Caswell, J. Nucl. Eng., 17, No. 7, 313 (1963).

Absolute Calibration of the National

Bureau of Standards Photoneutron

Standard: I., J. A. DeJuren, D. W.

Padgett, and L. F. Curtiss, J. Res.

Natl. Bur. Stand. (U.S.), 55, 63

(Aug. 1955).

References—Personnel Protection

Instrumentation

NBS Measurement Services: Neutron

Personnel Dosimetry, R. B. Schwartz, Natl. Bur. Stand. (U.S.),

Spec. Publ. 250-12 (July 1987).

Calibrations and Use of Filtered

Beams, R. B. Schwartz, Proc. Intl. Specialists Symp. on Neut. Stand,

and Applic, Gaithersburg, MD,

Natl. Bur. Stand. (U.S.), Spec.

Publ. 493, 250 (Oct. 1977).

88
The Design and Construction of a DjO-Moderated '"Cf Source for Calibrating Neutron Personnel

Dosimeters Used at Nuclear Power

Reactors, R. B. Schwartz and

C. M. Eisenhauer, U.S. Nucl. Reg.

Com. Doc. NUREG/CR-1204

(Jan. 1980).

References—Activation Detector Dosimetry

NBS Measurement Services: Activation Foil Irradiations at NBS by

Californium Fission Sources, G. P. Lamaze and J. A. Grundl. Natl. Bur. Stand. (U.S.), Spec. Publ. 250-

13 (Mar. 1988).

NBS Measurement Services: Activation Foil Irradiations at NBS by

Reactor Cavity Sources, G. P. Lamaze and J. A. Grundl, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-

14 (Mar. 1988).

Derivation of Neutron Exposure

Parameters from Threshold Detector Measurements, J. A. Grundl,

Proc. Sixth ASTM-Euratom Symp.

on Reactor Dosimeter, Jackson,

WY (June 1987).

Compendium of Benchmark Neutron

Fields for Reactor Dosimetry, J. A.

Grundl and C. M. Eisenhauer,

Natl. Bur. Stand. (U.S.), NBSIR

85-3151 (Apr. 1985).

The U.S. ^''U Fission Spectrum Stan- dard Neutron Field Revisited, E. D. McGarry, C. M. Eisenhauer,

D. M. Gilliam, J. A. Grundl, G. P. Lamaze, and A. Fabry, Proc. Fifth

ASTM-Euratom Symp. on Reactor

Dosimetry, Geesthacht, Germany

(Sept. 1984).

National Standards for Neutron Measurements, J. A. Grundl, Proc. of a Meeting on Traceability for Ionizing Radiation Measurements, Natl. Bur. Stand. (U.S.), NBS Spec.

Publ. 609 (Feb. 1982).

Utilization of Standard and Reference

Neutron Fields at NBS, C. M.

Eisenhauer, D. M. Gilliam, J. A.

Grundl, and V. Spiegel, Proc. Sec- ond ASTM-Euratom Symp. on Reactor Dosimetry, Palo Alto, CA

(Oct. 1977).

A Californium-252 Fission Spectrum

Irradiation Facility for Neutron

Reaction Rate Measurements,

J. A. Grundl, V. Spiegel, C. M.

Eisenhauer, H. T. Heaton II, D. M.

Gilliam (NBS), and J. Bigelow

(ORNL), Nucl. Tech. 32, 315

(Mar. 1977).

89
46010C-48020S

C. Dosimetry of X Rays, Gamma Rays,

and Electrons

Technical Contacts:

Bert M. Coursey

All Tests

Tel: 301/975-5584

Paul G. Lamperti

Tests 46010C46050S

Tel: 301/975-5591

James T. Weaver, Jr. Tests 47010C,

47011C, 47040S

Tel: 301/975-5586

Christopher G.

Soares

Tests 47030C47036C, 47040S, 48010M-48020S

Tel: 301/975-5589

Mailing Address: C214 Radiation Physics, Center for Radiation Research, National Institute of Standards and

Technology, Gaithersburg, MD 20899-0001

Shipment of Instruments: National Institute of Standards

and Technology, 1-270 at Quince Orchard Road, C214

Radiation Physics, Gaithersburg, MD 20899-0001

For: 46010C-46050S; Attn: P. J. Lamperti

For: 48010M-48020S; Attn: C. G. Soares

Shipment of Sources: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, B131

Radiation Physics, Gaithersburg, MD 20899-0001

For: 47010C-47040S;

Attn: Health Physics/J. T. Weaver

(for Gamma-Ray Sources)

Attn: Health Physics/C. G. Soares

(for Beta-Particle Sources)

Test No. Items

C.l X-Ray and Gamma-Ray Measuring Instruments 460 IOC Radiation Detectors—Calibration/Correction

Factor, One Beam Quality (See Table 12) 460 lie Each Additional Beam Quality or Condition

46020C Passive Dosimeters—Irradiation of Up to Six, One

Beam Quality at One Set-Up

4602 IC Up to Six Additional Dosimeters at Same Set-Up

and Beam Quality

46030S Special Tests of High-Gain Electrometers—Charge

Sensitivity, One Set of Switch Positions, with

46010C/46011C, by Previous Arrangement

46040S Special Tests of X-Ray Penetrameters, ArdranCrookes Type

46050S Special Tests of X-Ray and Gamma-Ray Measuring

Instruments C.2 Gamma-Ray Sources, Beta-Particle Sources, and Measuring Instruments 470 IOC Gamma-Ray Sources Similar to NIST Standards

•""Co or '"Cs Having Air-Kerma Strengths 10 to 1500 ixGy mVh, and '''l or '''^Ir Having Air-Kerma

Strengths 0.1 to 30 ju-Gy mVh

4701 IC Each Additional Gamma-Ray Source of Same

Radionuclide

47030C Beta-Particle Sources Calibrated for Surface Dose Rate 47035C Beta-Particle Sources Calibrated for Radiation

Protection

47036C Ionization Chambers Calibrated with Beta-Particle Sources for Radiation Protection

47040S Special Tests of Gamma-Ray and Beta-Particle Sources

C.3 Dosimetry of High-Energy Electron Beams

480 lOM Dose Interpretation of NIST-Packaged

Ferrous-Ferric (Fricke) Dosimeters Irradiated by

Customer—Three Dosimeters (Two for Irradiation,

One Control) 4801 IM Each Additional Dosimeter

48020S Special Tests of Electron-Beam Dosimeters

CO Special Instructions for Using

Electron and Photon Dosimetry

Calibration and Test Services

(46010C-48020S)

The NIST dosimetry calibration and

test services for x rays, gamma rays, beta particles, and electrons are per- formed in NIST's laboratories at Gaithersburg, Maryland. Inquiries

90
should be addressed to the appropriate technical contacts listed at the beginning of this section. The name and

telephone number of an individual

who can answer technical questions

that may arise must be given in any

inquiry, order, or shipment.

Upon receipt of a purchase order, a report number is assigned. Calibrations are generally performed in the

sequence established by those numbers, except when greater efficiency can be achieved by combining similar

calibrations, or when work for a cali- bration laboratory is given a higher

priority. Arrangements for calibration

must be made in advance by letter or

telephone, so that the instrument or source to be calibrated will not be

shipped to NIST until the time of its scheduled calibration approaches. In- quiry should be made as to scheduling and turn-around time.

Except for negligence by its per- sonnel, NIST assumes no responsibility for loss of or damage to the

instruments or sources while in its possession. The risk should be covered by insurance.

The report of calibration or test will carry a DG number (e.g., DG

9876/89). Subsequent reference to

that calibration or test should cite the

DG number.

C.l X-Ray and Gamma-Ray Measuring Instruments (46010C-46050S)

X-ray measuring instruments are cali- brated in terms of air kerma or exposure by a substitution method in an

x-ray beam at a point where the rate has been determined by means of a standard free-air ionization chamber.

In order to provide instrument cali- brations over a wide range of x-ray beam qualities, many combinations of

generating potential and filtration are

available. These are listed in Table 12

as lightly (L), moderately (M), and

heavily (H) filtered beams. Two

beam qualities that do not fit into

these categories are considered as special (S) qualities. Cobalt-60 and

cesium- 137 gamma-ray beams are also

available. The beam qualities are

identified by beam codes given in the

first column. The calibration beam

qualities requested should be appropriate to the instrument submitted.

Gamma-ray measuring instruments

are calibrated in terms of air kerma,

exposure, or absorbed dose at points

in the collimated cobalt-60 and ce- sium- 137 gamma-ray beams that have

been standardized by means of

graphite cavity chambers or a graphite calorimeter. Rates at the

time of calibration are computed

from the original beam standardization data and appropriate decay corrections. Ionization chambers

submitted for an air kerma or exposure calibration should have sufficient wall thickness to provide electron

equilibrium for the gamma-ray energy

selected. Ionization chambers submitted for an absorbed-dose calibration

must be suitable for calibration in a phantom.

An ionization chamber and elec- trometer combination, with the elec- trometer marked in terms of air kerma, exposure, or absorbed dose, is calibrated by providing a dimensionless correction factor for the elec- trometer scale. An ionization

chamber and electrometer combination marked in electrical units is cali- brated as follows: (1) the chamber is calibrated in terms of air kerma, ex- posure, or absorbed dose per unit charge using an NIST electrometer;

(2) the customer's electrometer is checked for linearity and charge measurement accuracy; and (3) the combination of chamber and electrometer

is checked for consistency. An ionization chamber submitted without an

electrometer is calibrated in terms of

air kerma, exposure, or absorbed dose

per unit charge. Calibration can be

based on measurements for positive or negative polarizing potential, or on

the mean of measurements for both

potentials, as requested. The ratio of

ionization currents for full and half polarizing potentials and the corre- sponding ionization current will be

stated in the calibration certificate.

91
Table 12: X-Ray Beam-Quality Parameters

Beam Added Filter Half-Value Homogeneity Effective Exposure Rate Code Layer Coefficient Energy Min. Max.

Al Cu Sn Pb Al Cu Al Cu (keV) (juGy/s) (mGy/s)

(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm)

LIO 0. 0.029 79 0.009 15 L15 0. 0.050 74 0.009 37 L20 0. 0.071 76 0.009 29 L30 0.265 0.22 60 0.009 4 L40 0.50 0.49 57 0.009 4 L50 0.639 0.75 58 0.009 4 L80 1.284 1.83 58 0.009 4 LlOO 1.978 2.8 59 0.009 4 M20 0.230 0.152 79 0.009 4.4 M30 0.50 0.36 64 0.009 3 M40 0.786 0.73 66 0.009 4 M50 1.021 1.02 0.032 66 62 0.009 4 M60 1.51 1.68 0.052 68 64 7 2 MlOO 5.0 5.0 0.20 72 55 9 3 Ml 50 5.0 0.25 10.2 0.67 87 62 9 4 M200 4.1 1.12 14.9 1.69 95 69 9 3 M250 5.0 3.2 18.5 3.2 98 86 9 2 M300 4.0 6.5 22. 5.3 100 97 4 0.7

HIO 0.105 0.048 89 0.009 0.03 H15 0.500 0.152 87 0.009 0.03 H20 1.021 0.36 88 0.009 0.03 H30 4.13 1.23 0.038 93 94 0.009 0.03 H40 4 05 0 26 2.9 0.093 94 95 0.009 0.03 H50 4.0 0.10 4.2 0.142 92 90 38 3 0.6 H60 4.0 0.61 6.0 0.24 94 89 46 0.2 0.04 HlOO 4.0 5.2 13.5 1.14 100 94 80 0.04 0.02 H150 4.0 4.0 1.51 17.0 2.5 100 95 120 0.3 0.09 H200 4.0 0.60 4.16 0.77 19.8 4.1 100 99 166 0.2 0.05 H250 4.0 0.60 1.04 2.72 22 5.2 100 98 211 0.3 H300 4.1 3.0 5.0 23 6.2 99 98 252 0.4 0.03

S75 1.504 1.86 63 0.009 4 S60 4.0 2.8 0.089 75 70 3 0.5

137^ 10.8 662 13 0.9 ""Co 14.9 1250 13 22

For the x-ray beam codes, the letter indicates light, moderate, heavy, and special filtration and the number

is the constant potential in kilovolts. The inherent filtration is approximately 1.0 mm Be for beam codes LIO-LIOO, M20-M50, H10-H40, and S75; and 3.0 mm Be for beam codes M60-M300, H50-H300, and S60. The half-value layers for '"Cs and '*Co are calculated. The homogeneity coefficient is taken as 100 x (1st HVL)/(2nd HVL).

The calibration distance is 25 cm for beam codes LIO, L15, HIO, and H15; 50 cm for beam codes L20-L100,

M20-M50, H20-H40, and S75; and variable for the remaining beam codes. To get exposure in R multiply air kerma in mGy ^ g

in mR

92
46010C-48020S

Ionization chambers are tested,

prior to calibration, for leakage, stabi- lization time, short-term stability, re- combination loss, and connection to the atmosphere. Chambers found unsuitable for calibration will be re- turned with a statement of the reason

for rejection. A charge may be made

for time incurred on the tests. Each instrument submitted to NIST for dosimetry calibration or

test must be uniquely identified, usually by the manufacturer's name,

model number, and instrument serial number. When the serial number is lacking, an alternative identifying

mark should be provided. If none is found, NIST will mark the piece

with an identification number. If the

apparatus submitted has been cali- brated previously by NIST, the serial number or identifying mark should be

given on the new order so that a continuing record of stability can be

maintained.

All shipments to NIST of instru- ments for dosimetry calibration must

be in reusable containers. Even if properly packed, there can be no as- surance that a calibrated instrument

has maintained its calibration during

shipment unless a method of verifying instrument stability has been es- tablished. Measurement should be

made of the instrument response both

before and after shipment, using a long-lived radioactive source and a highly reproducible measurement

procedure. A long-term record of in- strument stability using a suitable

constancy check procedure is the

most effective method for assuring

the validity of the instrument

calibration. Irradiation of passive dosimeters,

for readout by the customer, is avail- able for most of the beam qualities

listed in Table 12. These irradiations are generally in terms of air kerma or exposure; for passive dosimeters suit- able for insertion in a phantom, irra- diation in terms of absorbed dose can be provided by in-phantom irradia- tion using cobalt-60 gamma rays.

X-ray penetrameters, of the

Ardran-Crookes type, can be cali- brated using constant x-ray generating potentials up to 300 kV. These

penetrameters are used for measure- ment of the generating potential of

diagnostic x-ray units.

C.2 Gamma-Ray Sources, BetaParticle Sources, and Measuring

Instruments (47010C-47040S)

Sources submitted to NIST for^ dosimetry calibration are subject to the following conditions:

A. Preparation: Sources submitted for calibration must be sealed so

that there can be no escape of any ra- dioactive material, including any

gaseous decay products. The sources,

shielding, and packaging must be free of contamination. Contaminated or

leaking sources cannot be measured

and may cause considerable loss of

time and damage to laboratory facilities. Sources must have been sealed

for a sufficient time to be substantially in radioactive equilibrium with

their decay products when these contribute to the emitted radiation. B. Packaging for shipment: Packages must be in compliance with the

regulations of the Department of

Transportation as specified in DOT

49CFR 1 73 .40 1 - 1 73.478. Radionuclides

must be packaged as Limited Quantities (DOT 49CFR173.421) or in Type

A packages (DOT 49CFR173.412 and

173.433). Type A packages must bear

the appropriate radioactive-hazard la- bels (DOT 49CFR 172.403). If the source is considered by the shipper to be in DOT Special Form, a Special

Form certificate must be furnished to NIST in strict compliance with DOT

49CFR173.476. Copies of the codes

are available from the Government

Printing Office, Washington, DC

20402.

All shipments to NIST of gammaray and beta-particle sources should

be in reusable containers. A drawing

showing the source container and a description of the method of source removal should be provided before

the shipment is received at NIST.

93
Postal regulations preclude shipment

of dosimetry sources via the Postal

Service.

If the nature of the shipment re- quires a Type B container subject to an NRC quality assurance program,

documentation should be supplied to NIST certifying that the use of the

container by NIST is part of the pro- gram of the shipper. C. Possession of licensed materials: In submitting a source for cali- bration, it is necessary for the

submitter to certify that he is duly

authorized to possess the source un- der license by the applicable authority. In the case of individuals residing

in a State that has entered into agree- ment with the Nuclear Regulatory

Commission, State regulations are applicable to all sources. In :he case of

other individuals, NRC regulations

are applicable. This certification may

be by letter, by a suitable statement on the purchase order covering the

calibration fee, or by a clear copy of

the submitter's Possession License for the source. Calibration in terms of air kerma

strength (air kerma rate in free space

times the square of the distance of the

calibration point from the source center along the perpendicular bisector)

is provided for gamma-ray sources of

cobalt-60, cesium- 137, iridium- 192,

and iodine- 125. Calibration in terms of absorbeddose rate is provided for suitable en- capsulated beta-particle sources; the

dose rate to a low-atomic-number

material (graphite or plastic) is deter- mined by measurement with an ex- trapolation chamber. The betaparticle sources may be either small- area sources such as ophthalmic applicators, or large-area plaques, and

will be calibrated for absorbed dose

rate to water either at the source sur- face or at a specified distance.

Ionization chambers to be cali- brated with beta-particle sources must

be parallel-plate chambers with thin

walls. They can be calibrated with

the radionuclides ""Sr + '°Y, or ^^^l, or '*'Pm.

C.3 Dosimetry of High-Energy

Electron Beams (48010M-48020S)

Dosimeters are provided twice a year

to users requesting assistance with

absorbed-dose measurements in highenergy electron beams. The dosimeters consist of ferrous sulfate (Fricke)

solution in radiation-resistant silica- glass spectrophotometer cells. The

user irradiates all but one of the three

furnished dosimeters to between 50

and 80 Gy (5000 and 8000 rad) to water at electron energies between 5 and 50 MeV, employing the irradia- tion geometry (field size, phantom,

position of dosimeter in phantom)

given in the "Protocol for Dosimetry

of High-Energy Electrons," Physics

in Medicine and Biology 11, 505

(1966).

After irradiation, the dosimeters

are returned to NIST for spectrophotometric evaluation of the ferric-ion concentration in terms of absorbed

dose in the phantom, using the eG

product given in "Radiation Dosimetry: Electron Beams with Energies

between 1 and 50 HeV," ICRU Report 35 (1984).

References—Dosimetry of X Rays,

Gamma Rays, and Electrons

C.l X-Ray and Gamma-Ray

Measuring Instruments NBS Measurement Services: Calibration of X-Ray and Gamma-Ray

Measuring Instruments, P. J. Lamperti, T. P. Loftus, and R. Loevinger, Natl. Bur. Stand.

(U.S.), Spec. Publ. 250-16 (Mar.

1988).

The Photon-Fluence Scaling Theo- rem for Compton-Scattered Radiation, J. S. Pruitt and R. Loevinger,

Med. Phys., 9, 176 (1982).

The Graphite Calorimeter as a Stan- dard of Absorbed Dose for Cobalt60 Gamma Radiation, J. S. Pruitt,

S. R. Domen, and R. Loevinger,

J. Res. Natl. Bur. Stand. (U.S.), 86,

495 (1981).

94
Uncertainty in the Delivery of Absorbed Dose, R. Loevinger and

T. P. Loftus, Ionizing Radiation

Metrology, International Course at Varenna, Italy, 1974, E. Casnati,

Ed., G-6, 459, Editrice Compositori, Bologna (1977).

Medical Dosimetry Standards Pro- gram of the National Bureau of

Standards, R. Loevinger, Proc. Symp. on Natl, and Intl. Standardization in Rad. Dosimetry, Atlanta,

GA, Dec. 5-9, 1977, Intl. Atomic

Energy Agency, Vienna (1978).

(This article provides references

for earlier publications on NBS ex- posure and absorbed-dose stan- dards.)

Exposure Spectra from the NBS Vertical-Beam ^°Co Gamma-Ray

Source, M. Ehrlich and C. G.

Soares, Natl. Bur. Stand. (U.S.),

NBSIR 76-1117 (1976).

Spectrometry of a *'°Co Gamma-Ray

Beam Used for Instrument Calibration, M. Ehrlich, S. M. Seltzer, M.

J. Bielefeld, and J. I. Trombka,

Metrologia, 12, 169 (1976).

C.2 Gamma-Ray Sources, Beta-Particle

Sources, and Measuring Instruments NBS Measurement Services: Calibration of Gamma-Ray-Emitting

Brachytherapy Sources, J. T. Weaver, T. P. Loftus, and R. Loevinger, Natl. Bur. Stand.

(U.S.), Spec. Publ. 250-19 (1988).

NBS Measurement Services: Calibration of Beta-Particle Radiation In- strumentation and Sources, J. S. Pruitt, C. G. Soares, and M.

Ehrlich, Natl. Bur. Stand. (U.S.),

Spec. Publ. 250-21 (Apr. 1988).

NBS Measurement Services: Calibration of Beta-Particle-Emitting Ophthalmic Applicators, J. S. Pruitt, Natl. Bur. Stand. (U.S.), Spec.

Publ. 250-9 (July 1987).

Calibration of Beta-Particle Ophthalmic Applicators at the National

Bureau of Standards, J. S. Pruitt,

J. Res. Natl. Bur. Stand. (U.S.), 91,

165 (1986).

The Effect of Altitude on Beta-Ray

Source Calibrations, J. S. Pruitt,

Rad. Protec. Dosim. 11, 151 (1984).

Exposure Standardization of lodine125 Seeds Used for Brachytherapy,

T. P. Loftus, J. Res. Natl. Bur. Stand. (U.S.), 89, 295 (1984).

Standardization of Iridium- 192

Gamma-Ray Sources in Terms of

Exposure, T. P. Loftus, J. Res.

Natl. Bur. Stand. (U.S.), 85, 19 (1980).

Medical Dosimetry Standards Pro- gram of the National Bureau of

Standards, R. Loevinger, Proc. Symp. on Natl, and Intl. Standardization in Rad. Dosimetry, Atlanta,

GA, Dec. 5-9, 1977, Intl. Atomic

Energy Agency, Vienna (1978).

(This article provides references

for earlier publications on NBS ex- posure and absorbed-dose stan- dards.)

Standardization of Cesium- 137

Gamma-Ray Sources in Terms of

Exposure Units (Roentgens), T. P. Loftus, J. Res. Natl. Bur. Stand.

(U.S.), 74A, 1 (1970).

C.3 Dosimetry of High-Energy

Electron Beams

NBS Measurement Services: Fricke

Dosimetry in High-Energy Electron Beams, C. G. Soares, E. L.

Bright, and M. Ehrlich, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-4

(1987).

Uniformity of High-Energy ElectronBeam Calibrations, M. Ehrlich and

P. J. Lamperti, Phys. Med. Biol.

14, 305 (1969).

Proposed National Bureau of Stan- dards Program for the Calibration

of Instruments Used in HighEnergy Electron and X-Ray

Beams, M. Ehrlich, Ann. N.Y.

Acad. Sci. 161, 139 (1969).

95
49010C-49050S

Dosimetry for High-Dose Applications

Technical Contacts:

Dene G. Jimmy C. William L. Hocken Humphreys McLaughlin

Tel: 301/975-5577 Tel: 301/975-5582 Tel: 301/975-5559

Mailing Address: C214 Radiation Physics, National Insti- tute of Standards and Technology, Gaithersburg, MD

20899-0001

Test No. Items 49010C Calibration Irradiations of Customer-Supplied

Dosimeters with ^"Co Gamma Rays

49020C Dose Interpretation of NIST Transfer Dosimeters

Irradiated by Customer

49030C Dose Interpretation of Each NIST Transfer Dosimeter in Addition to Those Supplied

under 49020C

49040S Special Tests of Dosimeters by Reading with

Spectrophotometer, Optical Density at One to Five Wavelengths (Each Dosimeter)

4904 IS Spectrophotometric Readings of Dosimeters,

Ultra-Violet and Visible Spectrum Scan (Each Dosimeter)

49050S Special Measurement Services for Dosimeter

Response and Dose Distributions

Calibration Services and Special Tests

of Dosimeters (49010C-49050S)

The following dosimetry services are

for individual users of intense radiation fields, in particular large

gamma-ray sources and electron ac- celerators up to approximately 10 MeV. These services include the administering of known absorbed doses

of photons to customer-supplied

dosimeters; supplying calibrated

transfer standard dosimeters to cus- tomers for irradiation and subsequent

readout and dose interpretation; and

special measurement services such as

the determination of temperature dependence, dose-rate dependency or

reproducibility of dosimeter response.

Calibration of Dosimeters Irradiated

with *"Co Gamma Rays (49010C)

Calibration irradiations are available

for customer-supplied dosimeters

(such as solid radiochromic or liquid

chemical types) or test samples that are sent to NIST, where they are packaged appropriately to provide

electron equilibrium conditions. They

are irradiated in the NIST standard

cobalt-60 calibration facility to

specific agreed-upon absorbed dose

values in the nominal "high-dose"

range of 10-10^ grays (10'- 10* rads).

The dosimeters are then sent back to the customer for analysis and evaluation. Dosimeters should not exceed

dimensions of 1 cm X 2 cm X 5 cm.

Dene Hocken and Jimmy Humphreys use a cobalt-60

irradiator, consisting of 24 cobalt-60 sources sur- rounded by a massive lead shield, with an automatic

timer assembly to calibrate dosimeters.

96
49010C-49050S

Transfer Reference Standard

Dosimeters (49020C and 49030C)

NIST provides transfer standards in the form of sets of calibrated ra- diochromic dosimeters packaged in appropriate equilibrium materials

such as polystyrene or aluminum.

The sealed, packaged dosimeters are

sent to the customer for irradiation to nominal agreed-upon absorbed dose

levels in a prescribed geometrical ar- rangement. The unopened packaged

dosimeters are then returned to NIST

to be read and evaluated and the re- sults reported, thus providing calibra- tion of the customer irradiator. The

absorbed dose range that is suitable for use with the transfer dosimeters is

1 to 50 kGy (0. 1 to 5 Mrad) in water,

silicon, aluminum, graphite, or certain

plastics.

Special Tests of Dosimeters:

Spectrophotometric Reading

(49040S-49041S)

Dosimeters may be read at several

specific ultraviolet or visible optical

wavelengths or as a spectral scan over an appropriate wavelength re- gion of interest.

Special Measurement Services for Dosimeter Response and Dose

Distributions (49050S)

Tests of dosimeter response, such as temperature dependence, dose rate dependence, and dose distributions in specific irradiation geometries, can be

provided as special measurement ser- vices. These dose distribution measurements can include dose profiles in heterogenous absorbers and at inter- faces of different materials.

References—High-Dose Dosimetry

NBS Measurement Services: Dosimetry for High-Dose Applications,

J. C. Humphreys, D. Hocken, and

W. L. McLaughlin, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-11

(Mar. 1988).

Dosimetry for Industrial Radiation

Processing, W. L. McLaughlin,

J. C. Humphreys, and A. Miller, Natl. Bur. Stand. (U.S.), Spec.

Publ. 609 (1982).

A National Standardization Pro- gramme for High-Dose Measurements, W. L. McLaughlin,

Technical Report No. 205, 17, Intl. Atomic Energy Agency, Vienna

(1981).

Dye Film Dosimetry for Radiation

Processing, J. C. Humphreys and

W. L. McLaughlin, IEEE Trans. Nucl. Sci., NS-28, 2, 1797 (Apr.

1981).

The Measurement of Absorbed Dose

and Dose Gradients, W. L. McLaughlin, Radiat. Phy. Chem.,

15, 9 (1980).

Dosimetry Standards for Industrial

Radiation Processing, W. L. McLaughlin, National and International Standardization of Radiation

Dosimetry, 1, Intl. Atomic Energy

Agency, Vienna (1978).

97
Chapter

A Resistance Measurements B Impedance Measurements C Voltage Measurements D Precision Ratio Measurements E Phase Angle Measurements F Power and Energy Measurements,

Low-Frequency

G Microwave Measurements H Noise Temperature Measurements

/ Electromagnetic Field Strength and Antenna Measurements J Pulse Waveform Measurements
Electromagnetic Measurements 51100S-51163C

1

Resistance Measurements

A. 1 DC Resistance Standards and

Measurements

Technical Contacts:

Ronald F. Norman B. Denise D. Dziuba Belecki Prather

Tel: 301/975-4239 Tel: 301/975-4223 Administrative and Logistics

Tel: 301/975-4221

Mailing Address: B146 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 51100S Special Resistance Measurement Services, by

Prearrangement

51110M Measurement Assurance Program Services for Resistance 51130C Standard Resistor, Thomas-Type, 1 Q. 51131C Standard Resistor, Evanohm Wirewound High

Precision, 10 kfl 51132C Standard Resistor, Four-Terminal, 0.0001 Cl 51133C Standard Resistor, Four-Terminal, 0.001 O

51134C Standard Resistor, Four-Terminal, 0.01 fi 51135C Standard Resistor, Four-Terminal, 0.1 H

51136C Standard Resistor, Four-Terminal, 1 fl 51137C Standard Resistor, Four-Terminal, 10 fl 51138C Standard Resistor, Four-Terminal, 100 H

51139C Standard Resistor, 1 kH

51 HOC Standard Resistor, 10 kil 51141C Standard Resistor, 100 kO

51142C Standard Resistor, 1 MH

51143C Standard Resistor, 10 Mfl

51144C Additional Voltage

51145C Standard Resistor, 100 Mfl

Test No. Items

5 1 1 46C Additional Voltage

51147C Standard Resistor, 1 Gfi

5 1 148C Additional Voltage

51149C Standard Resistor, 10 on

5 1 1 50C Additional Voltage

51151C Standard Resistor, 100 G£l

5 1 1 52C Additional Voltage

51153C Standard Resistor, 1 TCi

51154C Additional Voltage

51 160C Standard Resistor for Current Measurements

(Shunts), One Range, One Current Not to Exceed

300 A (May & Nov.)

51161C Standard Resistor for Current Measurements

(Shunts), One Range, One Current between 300 A

and 1000 A (May & Nov.)

51162C Standard Resistor for Current Measurements

(Shunts), Additional Range of a Multi-Range

Resistor (May & Nov.)

51163C Standard Resistor for Current Measurements

(Shunts), Additional Determination at Another

Current Level (May & Nov.)

99
Special DC Resistance Measurements,

by Prearrangement (51100S)

Testing or evaluation of prototype re- sistance standards or measuring in- struments; unique resistance

measurements; and other calibration

services not specified below, such as the determination of the pressure coefficient of Thomas-type resistors, the

determination of the temperature coefficient of standard resistors, and the

calibration of resistance standards in

oil at temperatures other than 25 °C, are carried out under this test number. Such measurements are made at the discretion of the NIST technical

staff in a manner specifically agreed

upon by the customer and the expert

involved. Testing of component resis- tors will only be considered under

the rare circumstance that the behavior of the resistors has been observed

to approximate that of state-of-the-art standards under the same conditions.

Measurement Assurance Program

Services for Resistance (51110M)

Resistance MAP transfers are generally carried out at the 1-ohm and

10-kilohm levels. Four wellcharacterized commercial standard

resistors are used as transport stan- dards. The suggested measurement

schedule at the client laboratory consists of measurements on each trans- port resistor three times a week for a period of 4 to 6 weeks, depending

upon the settling time of the resistors due to transportation effects. Participation in this program is generally not advisable unless one is required to support resistance measurements at or near state-of-the-art accuracies and is willing to adopt a system for the continuous surveil- lance of standards during the inter- vals between NIST MAP transfers. A

successful transfer requires a considerable amount of data collection and

a willingness to become involved in the data analysis process. Data supplied in the course of routine NIST

calibrations suffice for normal measurement requirements of standards

laboratories if proper methods are

used by the laboratory to quantify the

additional uncertainties caused by

transportation and the laboratory's

own measurement process.

Special Standard Resistors 1 SI and

10 kSl (51130C and 51131C)

Thomas-type 1 ohm resistors or their equivalent are calibrated directly

against the NIST 1 ohm reference

group that is used to maintain the U.S. legal ohm. Special 10-kilohm

standard resistors designed for air or

011 use are calibrated directly against

the NIST 10-kilohm working stan- dards. The special 10-kilohm standard

resistors (Evanohm wirewound highprecision or equivalent) are characterized by resistance corrections

within 10 ppm of nominal value, temperature coefficients of 0±1 ppm/°C

at the operating temperature, and

drift rates of < 1 ppm/year.

The customer resistors are acclimatized in their respective test environments for approximately 1 week prior

to their calibration. Measurement

parameters of temperature and current level are as follows:

Resistor Medium Temperature Current

(°C)

1 fl oil 25.00+0.003 100 mA

lOkfl oil 25.00±0.01 1mA

lOkfi air 23.0 ±1.0 1 mA

The temperature of the customer re- sistor at the time of the measurement

is given in the report of calibration. Since the Thomas-type resistor exhibits a significant pressure coefficient, the barometric pressure at the

time of the measurement is also re- ported. Uncertainties are based upon

(1) the random behavior of the measurement process as characterized by

data from a large population of indi- vidual calibrations, and (2) an esti- mate of the systematic errors. Uncertainties are listed in Table 13 on the next page.

Standard Resistors lO ^-lO" il (51132C-51142C)

Standard resistors with nominal

decade values in the range between

100
10 * and 10^ ohm are calibrated by

comparison with NIST working stan- dards of equivalent value. In general,

these standards are characterized by

(1) resistance corrections within 500

ppm of nominal value, (2) temperature coefficients of <10 ppm/°C at the temperature of use, and (3) drift rates of <5 ppm/year. Normally,

standard resistors are measured in an

011 bath maintained at 25.0±0.05 °C,

and at a power level of <0. 1 W. Resistors in temperature-controlled en- closures with fixed terminations are

also accepted for calibration. At the

levels of accuracy involved, four- terminal measurements are required

for resistors whose nominal values

are 100 ohms or less. Uncertainties

are based upon (1) the random behavior of the measurement process as characterized by data from a large

population of individual calibrations,

and (2) an estimate of the systematic

errors. Uncertainties are given in Table 13.

Table 13: Calibration Uncertainties

for DC Resistance Standards

Nominal Maximum

Test Resistance Terminal Power Uncertainty

Number (ohms) Connection (mw) (ppm)

51130C 1 (Thomas) 4 10 0.08 51131C 10"* (Special) 5 10 1 51132C 10-* 4 100 20 51133C 10-^ 4 100 12 51134C 10-2 4 100 7 51135C 10-' 4 100 5 51136C 1 4 100 3 51137C 10 4 100 4 51138C 10^ 2 100 4 51139C 10^ 2 100 5 51140C 10-* 2 100 7 51141C 10' 2 100 10 51142C 10^ 2 100 15 51143C 10^ 3

* 20-2000

51145C 10' 3

* 100-2000

51147C 10" 3

* 2000

51149C lO'o 3

* 2000

51151C 10" 3

* 2000

51153C 10'^ 3

* 2000

Resistors at this level are tested at customer-specified voltages up to 1 kV.

High-Valued Standard Resistors:

lO'-lO" SI (51143C-51154C)

High-value standard resistors in the range between 10' and 10'' ohms are

calibrated in an air bath maintained at a temperature of 23.0±0.5 °C and at a relative humidity of 35 ±5 percent.

Customer resistors are compared 1:1 with NIST working standards of the same nominal value up to and including the 10'" ohms level. Above 10'" ohms, 10:1 and 100:1 ratio techniques

are employed. The maximum test voltage is 500 volts for resistors < 10'" ohms and 1000 volts for resis- tors >10'" ohms. Uncertainties depend upon the stability and per- formance of the specific resistor involved and are given in Table 13. Only resistors that are mounted in a shielded enclosure with a permanent

identifying number and have suitable terminations are accepted for calibration. The resistance of thin-film, highvalued resistance standards is fre- quently highly voltage dependent.

Hence, the magnitude of the test voltage should be specified by the

customer when a resistor is submitted

for calibration. The temperature, rela- tive humidity, and test voltage of the

resistor are given in the report of cal- ibration.

High-Current Standard Resistors

Shunts (51160C-51163C)

Four-terminal standard resistors for use in the precise measurement of

high direct currents (shunts) are cali- brated by NIST only during May and

November of the calendar year. Ar- rangements should be made with

NIST prior to submitting a resistor for calibration. Normally only resis- tors of 0.04 percent accuracy or better are calibrated. The maximum test current available is 1000 amperes.

The uncertainty of measurement depends largely upon the performance

of the customer resistor involved.

101
Jack Neal adjusts the NIST measuring system for calibrating 10,000-ohm

standard resistors. Some customers' standards can be seen in tfie batli to the

right of the central column.

References—DC Resistance

Monitoring the U.S. Legal Unit of

Resistance via the Quantum Hall

Effect, M. E. Cage, R. F. Dziuba,

B. F. Field, T. E. Kiess, and C. T. Van Degrift, IEEE Trans. Instrum. Meas., IM-36, 222 (June 1987).

The NBS Ohm Past-Present-Future, R. F. Dziuba, Proc. Meas. Science

Conf., Irvine, CA (Jan. 1987).

A Test of the Quantum Hall Effect as a Resistance Standard, M. E. Cage,

R. F. Dziuba, and B. F. Field,

IEEE Trans. Instrum. Meas., IM34, 301 (1985).

Automated NBS 1-Ohm Measurement System, K. R. Baker and

R. F. Dziuba, IEEE Trans. In- strum. Meas., IM-32, 154 (1982).

An Integrated System for the Precision Calibration of Four-Terminal

Standard Resistors, T. E. Wells and

E. F. Gard, IEEE Trans. Instrum. Meas., IM-20, 253 (Nov. 1971).

Calibration Procedures for Direct

Current Apparatus, P. Brooks,

Natl. Bur. Stand. (U.S.), Monogr.

39 (Mar. 1962).

Measurement of Multimegohm Resistors, A. H. Scott, J. Res. Natl. Bur. Stand. (U.S.), 50, No. 3 (Mar.

1953).

Precision Resistors and Their Measurement, J. L. Thomas, Natl. Bur.

Stand. (U.S.), Circular 470 (Oct.

1948).

Methods, Apparatus, and Procedures

for the Comparison of Precision

Standard Resistors, F. Wenner,

J. Res. Natl. Bur. Stand. (U.S.), 25, Res. Paper RP1323 (Aug. 1940).

102
Resistance Measurements

m A.2 High-Voltage Standard Resistors

References—High-Voltage Standard

Resistors

High-Voltage Divider and Resistor

Calibrations, M. Misakian, Natl. Bur. Stand. (U.S.), Tech. Note

1215 (July 1985).

Technical Contacts: Special Shielded Resistor for HighVoltage Measurements, J. H. Park,

J. Res. Natl. Bur. Stand., 66C,

No. 1, 1924 (Jan.-Mar. 1962).

Martin Misakian

Tel: 301/975-2426

Robert E. Hebner, Jr. Tel: 301/975-2403

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

[Attn: M. Misakian, Bldg. 220, Room B344]

Test No. Items

5 12 IOC High-Voltage Standard Resistors

A routine calibration service is maintained for resistors designed for do

high-voltage applications. This ser- vice is for nearly corona-free resistors designed for dc operation between 10 kV and 150 kV.

Resistors can be hand-carried or shipped to NIST. If they are shipped,

they should be packaged in sturdy

reusable containers. The design of

many high-voltage resistors makes

them vulnerable to shear-type forces, so provisions should be made to minimize the likelihood of damage due to such forces when the device is in the

shipping container.

High-Voltage Standard Resistors

(51210C)

103
1310S

Resistance Measurements

a A.3 High-Frequency Standard Resistors

Technical Contacts:

George M. Free Ramon L. Jesch Kathy Hillen

Tel: 303/497-3609 Tel: 303/497-3496 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 51310S High-Frequency Standard Resistors, Two-Terminal

George Free calibrates a customer's high-frequency

standard resistor using the NIST twin-tee impedance

bridge.

References—High-Frequency Standard

Resistors

The Measurement of Lumped

Parameter Impedance: A Metrology Guide, R. N. Jones, Natl. Bur.

Stand. (U.S.), Monogr. 141 (June

1974).

Impedance of Lumped Circuits, L. E. Huntley and R. N. Jones, Proc. IEEE, 55(6), 900 (June 1967).

High-Frequency Standard Resistors

(51310S)

The overall frequency range covered

is 10 kHz to 250 MHz. The range of

resistance that can be calibrated depends upon the measurement fre- quency, as follows:

Frequency Range Resistance Range

10 kHz-2 MHz O.m to 1 MH

2 MHz- 10 MHz 50 n to 1 MVl

10 MHz- 100 MHz 20 Vl to 50 kH

100 MHz-250 MHz 20 ft to 20 kft Measurement uncertainties are given

in the reference; the minimum uncertainty provided is ±0.1 percent.

Reports of Calibration or Tests for

resistors will include the inductance

or capacitance associated with the resistor. Equivalent series values are normally given for inductive resistors and equivalent parallel values for ca- pacitive resistors.

104
1.

Resistance Measurements

A.4 AC Resistors

Technical Contacts:

T. Michael Barry A. Bell Souders Tel: 301/975-2419

Tel: 301/975-2406

Mailing Address: B162 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 51410S Special Tests of AC Resistors, by Prearrangement

Special Tests of AC Resistors (51410S)

Properly designed four-terminal ac

resistors in the range of 0. 1 ohm to 0.001 ohm can be measured at current ratings not to exceed 50A. The

values for the ac resistance and phase

angle (or time constant) can be re- ported for frequencies between 50 Hz

and 10 kHz. To be accepted for test, resistors must have phase angles no

greater than 0.01 radian at all re- quested test frequencies.

This service is offered as a specialtest service; fees will be based on actual costs. Prior arrangements are

essential.

i

References—AC Resistors

An Audio Frequency Four-Terminal

Resistance Bridge, T. M. Souders,

IEEE Trans. Instrum. Meas., IM23, No. 4, 342 (Dec. 1974).

105
52110S-52181C

JC7 Impedance Measurements (Except Resistors)

m^m B. 1 Low-Frequency Capacitance and

Inductance Measurements and Standards

Technical Contacts:

Bruce F. Field

Tel: 301/975-4230

Norman B. Belecki

Tel: 301/975-4223

Denise D.

Prather

Administrative and Logistics

Tel: 301/975-4221

Mailing Address: B146 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

521 lOS Special LF Impedance Measurements, by

Prearrangement

52130C Standard Fixed, Fused-Silica Dielectric Capacitor

(10 and 100 pF at 100, 400, or 1000 Hz)

52131C Additional Frequency Points 52 HOC Fixed Three-Terminal, High-Precision Standard

Capacitor with Coaxial Connectors (1 frequency

high accuracy under controlled conditions, 100, 400, or 1000 Hz)

52141C Additional Frequency Points 52150C Physical Tests to Qualify Three-Terminal Air

Capacitor for Measurement under 52 HOC

52160C Fixed Three-Terminal Standard Capacitor with

Coaxial Connectors (1 frequency, laboratory

conditions, 100, 400, or 1000 Hz)

52161C Additional Frequencies

52170C Two- or Three-Terminal Solid Dielectric Standard

Capacitor (66-2/3, 100, 400, 1000, or 10,000 Hz)

5217 IC Additional Frequencies and/or steps (for decade

capacitors)

52180C Fixed Inductor, Self or Mutual (100, 400, 1000, or

10,000 Hz)

521 SIC Additional Points

Low-Frequency Capacitance and

Inductance Measurements and

Standards (52181C)

These services cover the calibration

of standard capacitors and inductors

in the audio-frequency range. Threeterminal standard capacitors having

fused-silica (10 and 100 pF), and gas

(0.001 to 1000 jaF), dielectrics can be

measured at 100, 400, and 1000 Hz.

Two-terminal capacitors with either

air, mica, or polystyrene dielectrics can be measured at 100, 400, 1000,

and 10,000 Hz. Capacitors in the

range from 1 microfarad to 100 microfarad, including decade (plug or

rotary switch types—noninductive), can be calibrated at 66-2/3, 100, 120,

400, or 1000 Hz. Air-core standard

inductors having nominal values be- tween 0.01 mH and 10 H can be measured over the same frequency range. Standard inductors of 100 mH or less can also be measured at 10 kH.

Calibration services for some types

of capacitance standards at frequencies as low as 1 kHz can be provided

by the NIST Boulder Laboratory

provided the accuracy requirement

does not exceed ±0.01 percent. In some circumstances this can eliminate

the necessity of sending a standard to both Gaithersburg and Boulder Laboratories for a complete calibration. See also tests 52210C-52310C for cal- ibration services for capacitors at higher frequencies. For additional details please inquire at NIST/Boulder:

Telephone (303) 497-3609.

Special LF Impedance Measurements,

by Prearrangement (52110S)

This service provides for the testing or evaluation of prototype impedance

standards or measurement instrumentation at the state-of-the-art, and

other impedance measurements (such

as the calibration of decade or vari- able capacitance standards), at the

discretion of NIST technical experts.

Component capacitors, inductors, and

106
resistors are not considered for test by NIST unless their performance ap- proximates that of the best available

standards. Even under those conditions, only limited testing will be

done to ascertain the possible use of

the components in precision measure- ment applications.

Standard Fixed, Fused-Silica

Dielectric Capacitors

(52130C-52131C)

Fused-silica dielectric standard capacitors are generally submitted in temperature-controlled ovens due to their 10-ppm/degree temperature coefficient. Because of the magnitude of

the temperature coefficient, it is rec- ommended that a calibrated temperature sensor be permanently mounted

in the oven and thus included for the calibration. For baths not so equipped, the temperature is measured in terms of the International

Practical Temperature Scale of 1968

as amended in 1975 [Metrologia 12, 7

(1976)], using a standard platinum re- sistance thermometer.

Calibrations are carried out at 100,

400, or 1000 Hz, or any combination

of these chosen by the client. A minimum of eight measurements are made

over a 2-week or longer period, comparing the test capacitor directly with

an NIST fused-silica standard at 10 pF. The number of readings taken depends on the stability of the temperature controller in the oven containing

the test capacitors and can be as high

as 14. The averages of the measured

values of capacitance and temperature are reported. The uncertainty of

the reported capacitance value depends on the stability of the temperature as well as on the performance of

the capacitance standard itself. Because the temperature coefficients of

individual standards are not known

quantitatively, the results are not temperature corrected. Despite these factors, the uncertainty can be as low as

0.1 ppm.

Fused-silica dielectric standards not submitted in their own temperaturecontrolled oven are calibrated in stirred oil at a temperature of 25 °C.

If they are supplied with built-in sensors, the sensors and the bath temperature are both measured.

Standard Capacitors (52140C-52171C)

The following guidelines apply to the

calibration of standard capacitors at NIST.

Calibrations are ordinarily per- formed at a normal laboratory ambient temperature of 23±1 °C except

for high-stability gas dielectric capacitors. These are placed in a highly in- sulated chamber for 48 hours to achieve temperature stability during

calibration. The calibration temperature of about 23 °C is reported to within ±0.1 °C. Relative humidity is maintained at 50 percent or less in all cases. Precision three-terminal gas dielectric capacitors, such as ESI Model

SCIOOO and GENRAD Model 1404,

have been found to be variously af- fected by mechanical shock and ori- entation. Accordingly, two types of

calibrations are offered. The higher

accuracy calibration (52140C) re- quires a qualification test (52150C) to determine the effect on capacitance

of various impacts and changes in ori- entation. Results of this test are coupled with the random error of the

precision calibration which follows to provide a more complete uncertainty

for the calibration process. For the

lower accuracy test (52160C), a similar calibration, albeit with reduced

resolution, is performed, but no physical testing is performed. The as- signed uncertainty is fixed and has

been deduced from an analysis of

data taken from tests on a large population of standard capacitors.

The frequencies available for ca- pacitance calibrations depend upon

the type of capacitor and its connectors. In general, capacitors with coaxial connectors (Type 900) can be

calibrated at 100, 400, and 1000 Hz.

Capacitors with binding posts or PL

274 pins can be calibrated at 66-2/3,

100, 400, 1000, and 10,000 Hz.

107
The capacitance value given is the

equivalent parallel capacitance. In

general, an accurate determination of

the equivalent parallel conductance

with high accuracy is not feasible. However, for solid dielectric capacitors an approximate value is given

without charge.

The uncertainty stated in the report

of calibration is determined in part by

the accuracy of NIST's measurements

and in part by the characteristics of

the capacitor itself. The uncertainty is sufficiently broad to allow for varia- tions in the stray capacitance at the

connectors, variations in temperature

of a few degrees Celsius, considerable

variation in relative humidity and at- mospheric pressure, and frequency

deviations of a few percent from the

stated test conditions. 0\ er the above

frequency range, and in the capaci- tance range from 0.001 to 100 ju.F, the uncertainty usually lies in the

range 0.0005 to 0.5 percent. The uncertainties do not include allowances

for effects of transportation; these

must be determined by the owner us- ing pre- and post-calibration data

from his own facility.

Capacitors requiring terminal plugs

(banana plugs) for parallel connection

should be sent to NIST, together

with the plugs that will be used with

the capacitor after calibration. If such

a capacitor arrives without plugs,

NIST must attach plugs temporarily

in order to calibrate the capacitor.

The plugs used by NIST are GENRAD Type 274-P. If, after calibration

with these plugs, the capacitor is used

with plugs of even slightly different length and base, the capacitance can

differ significantly from that reported.

Unless otherwise requested, the measured value reported by NIST is the

capacitance added when the standard

is plugged directly into the binding

posts of the NIST bridge. For twoterminal GENRAD capacitors Type

1401, Type 509, and Type 1409

(when used as a two-terminal capacitor), a capacitance increase ranging

from 0.01 to 0.04 pF has been found

for different plugs. No significant

change in conductance has been

found in either the two-terminal or

three-terminal value. The importance

of terminal connection methods be- comes extremely critical when capacitance values of 0.01 jnF or less are being measured. Improved accuracy

in two-terminal measurement can be

realized if standards are provided

with precision coaxial connectors.

In the case of direct or three- terminal capacitance standards, the

connectors are assumed to be coaxial. While the connectors available for

this purpose are adequate, it should

be noted that changes or instabilities in the impedance of the shield or guard connection of a three-terminal

capacitor can change the capacitance

significantly.

Unless otherwise specified in the customer's purchase order, capacitors

with solid dielectric —except for

fused-silica capacitors—will be cali- brated as two-terminal capacitors

(measurement of "grounded" capacitance, case connected to low terminal).

Standard Inductors, Self or Mutual

(52180C-52181C)

Standard inductors for use in ac

bridges are tested at a room temperature of 23 °C and a relative humidity

of 50 percent or less. Measurements

at 10,000 Hz are limited to standard

inductors of 0. 1 H or less. Most in- ductors used at 60 Hz can be tested

at 100 Hz since the variation of in- ductance with frequency in this range

is usually negligible. A metal-encased

standard is calibrated with the case connected to the "low" terminal of

the inductor unless other conditions

are specified.

108
References—Low-Frequency Capacitance and Inductance Standards

Testing to Quantify the Effects of

Handling of Gas Dielectric Stan- dard Capacitors, C. R. Levy, Natl. Bur. Stand. (U.S.), Tech. Note

1161 (1982).

Transportable 1000 pF Standard,

G. M. Free and J. J. Morrow,

Natl. Bur. Stand. (U.S.), Tech.

Note 1162 (1982).

New Measurements of the Absolute

Farad and Ohm, R. D. Cutkosky,

IEEE Trans. Instrum. Meas.,

IM-23, No. 4, 305 (Dec. 1974).

Applications of Coaxial Chokes to AC Bridge Circuits, D. N. Homan,

J. Res. Natl. Bur. Stand. (U.S.),

72C, No. 2 (June 1968).

Improved Ten-Picofarad Fused Silica Dielectric Capacitor, R. D.

Cutkosky and H. L. Lee, J. Res.

Natl. Bur. Stand. (U.S.), 69C, No.

3, 173 (Sept. 1965).

Calibration of Inductance Standards

in the Maxwell-Wein Bridge Circuit, T. L. Zapf, J. Res. Natl. Bur. Stand. (U.S.), 65C, No. 3 (Sept.

1961).

Capacitance Bridge—NBS Type 2, R. D. Cutkosky, Natl. Bur. Stand.

(U.S.), Report 7103 (Mar. 1961).

109
52210S-52310S

a7 Impedance Measurements (Except Resistors)

B.2 High-Frequency Standard Capacitors

and Inductors

Technical Contacts:

George M. Free Ramon L. Jesch Kathy Hillen

Tel: 303/497-3609 Tel: 303/497-3496 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items

522 lOS Two-Terminal, Low-Loss Standard Capacitors

10 kHz to 250 MHz; 1 pF to 1 \iP 522 lie Two-Terminal, Low-Loss Standard Capacitors

(High Accuracy)— 1 MHz; 50, 100, 200, 500, and 1000 pF

52220S Three-Terminal, Low-Loss Standard Capacitors

100 kHz, 1 MHz; lO"" pF to lO' pF

5222 IC Three-Terminal, Low-Loss Standard Capacitors

(High Accuracy)— 100 kHz, 1 MHz; 10 ", 10"',

1, 10, 10-, and 10' pF

52222S Three-Terminal (MacLeod and Hanopol)

Capacitors—465 kHz; 0.001 to 10 pF

52223S Auxiliary Unit for 52222S

523 lOS Two-Terminal, High-Q Standard Inductors

(10 - /i,H to 1 H)

High-Frequency Standard Capacitors

and Inductors (52210S-52310S)

Services provided in this category

(and also Test Nos. 513 lOS and

52700C) are for passive devices over

the frequency range from 10 kHz to 250 MHz. Highest accuracy is obtained only for standards equipped

with precision coaxial connectors. Standards submitted for calibration

should be in good repair and, except

for very minor cleaning of connector

surfaces, should require no precalibration maintenance. NIST does

not provide repair services; items re- ceived that require maintenance will be returned to the sender and a handling fee charged.

Calibration services for some types

of capacitance standards at frequencies as low as 1 kHz can be provided

by the NIST Boulder Laboratory

provided the accuracy requirement

does not exceed ±0.01 percent. In some circumstances this can eliminate

the necessity of sending a standard to both the Gaithersburg and Boulder

Laboratories for a complete calibration. For additional details please

consult with the technical contact

listed at the beginning of this section.Calibration service for measuring

instruments such as bridges or meters

is not provided. The accuracy of

these instruments should be verified

by the owner through the use of sta- ble standards especially selected for particular values and frequencies ap- propriate to the instrument in question. All calibrations are performed un- der typical ambient laboratory conditions of 23 °C, and an atmospheric

pressure of approximately

8.4±0.2X 10' Pa at Boulder, Colorado. Services at ambient conditions

outside these limits are not provided.

Also, the power applied to any

device being calibrated does not ex- ceed 1 W. Additional information

pertaining to immittance (impedance

and admittance) measurement and

standards is contained in the refer- ences.

Two-Terminal, Low-Loss Standard

Capacitors (52210S-52211C)

In the frequency range from 10 kHz

to 250 MHz, capacitance calibrations

to a minimum uncertainty of ±0.1

percent are available from 1 pF to 1 jLiF depending upon frequency. The

upper capacitance limit for calibra- tion decreases as the frequency in- creases and is 50 pF at 5 MHz and

above.

110
At 1 MHz a special high-accuracy

service is available for capacitors

with nominal values of 50, 100, 200,

500, and 1000 pF provided they are equipped with 14-mm coaxial connectors. Reports of calibration for capacitors normally do not give conductance values. This is because

capacitors of standard quality, especially those with air-dielectric, have

conductance values too small to be

measured accurately at the present

state-of-the-art. A technique for extrapolating the

1-kHz values of capacitance standards

to high frequencies is described by

R. N. Jones (see references). This ref- erence describes a technique for obtaining a high-frequency value of a capacitor equipped with an un- shielded (banana plug) connector. The measurement technique yields ef- fective capacitance values at high fre- quencies using the capacitance value

at 1 kHz and the residual series in- ductance. The same technique, with some modifications, is usable for three-terminal and four-terminal pair

capacitors. It is emphasized that these

extrapolation procedures are only us- able for air dielectric capacitors or

capacitors with insulating materials

whose dielectric constant does not change with frequency.

Three-Terminal, Low-Loss Standard

Capacitors (52220S-52221C)

Fixed-value reference standards are maintained by NIST for values of 10, 100, and 1000 pF. High-quality three- terminal air dielectric capacitance

standards should have low residual

series inductance (<0.1 ;xH). This be- ing the case, it may be assumed that to an accuracy of ±0.10 percent, the

capacitances of standards of 1 pF or

less with air dielectric is the same at

1 MHz as it is at 1 kHz. Thus, it is unnecessary to have capacitors

smaller than 10 pF calibrated at

1 MHz.

Two-Terminal, High-Q Standard

Inductors (52310S)

In the frequency range from 10 kHz

to 250 MHz, inductance calibrations

to a minimum uncertainty of ±0.1

percent are available from 0.01 fxH to

1 H. The upper inductance limit for calibration decreases as the frequency

increases and is 1 fxH at 250 MHz. In the Report of Calibration, the resis- tance of the inductor is also given.

Service is available only for aircore

inductors or inductors whose value is independent of current.

References—High-Frequency Standard

Capacitors and Inductors

Evaluation of Three-Terminal and

Four-Terminal Pair Capacitors at High Frequencies, R. N. Jones,

Natl. Bur. Stand. (U.S.), Tech.

Note 1024 (Sept. 1980).

The Measurements of Lumped

Parameter Impedance: A Metrology Guide, R. N. Jones, Natl. Bur.

Stand. (U.S.), Monogr. 141 (June

1974).

A Precision High-Frequency Calibration Facility for Coaxial Capacitance Standards, R. N. Jones and

L. E. Huntley, Natl. Bur. Stand.

(U.S.), Tech. Note 386 (Mar. 1970).

Impedance of Lumped Circuits, L. E. Huntley and R. N. Jones, Proc. IEEE 55(6), 900 (June 1967).

A Technique for Extrapolating the

1 kc Values of Secondary Capacitance Standards to Higher Frequencies, R. N. Jones, Natl. Bur. Stand. (U.S.), Tech. Note 201

(Nov. 1963).

1 11
52400C

B. Impedance Measurements (Except Resistors)

B.3 Power-Frequency Capacitors

Technical Contacts:

William E. Robert E. Anderson Hebner, Jr. Tel: 301/975-2423 Tel: 301/975-2403

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

[Attn: W. E. Anderson, Bldg. 202, Room 167]

References—Power-Frequency

Capacitors

A Calibration Service for Voltage

Transformers and High-Voltage

Capacitors, W. E. Anderson, Natl. Bur. Stand. (U.S.), Spec. Publ.

250-33 (June 1988).

An International Comparison of

High-Vokage Capacitor Cahbrations, W. E. Anderson, R. S. Davis, O. Petersons, and W. J. M.

Moore, IEEE Trans. Power Appar. Syst., 97, 4, 1217 (July 1978).

A Wide Range High-Voltage Capacitance Bridge with One-ppm Accuracy, O. Petersons and W. E. Anderson, IEEE Trans. Instrum. Meas., IM-24, 4, 336 (Dec. 1975).

Test No. Items 52400C Power-Frequency Capacitors

Power-Frequency Capacitors (52400C)

A calibration service is maintained

for capacitors designed for 60-Hz operation, especially at vohages above

100 V. Typical uncertainties for a cal- ibration are ±100 ppm of the capacitance, and ± 1 percent of the

dissipation factor ±1x10 I Routine

calibrations are limited to devices

with a dissipation factor of 0.011 or

smaller and which are operated at sufficient voltages that at least 40 jLiA passes through the device under test. The high-power limit for routine

tests is 10 kVA. Some capability to perform tests outside of these limits

exists, and NIST should be contacted

to discuss special arrangements for such tests.

112
52710C-5271 1C

B.

Impedance Measurements (Except Resistors)

B.4 Q-Standards

Technical Contacts:

George M. Free

Tel: 303/497-3609 Ramon L. Jesch

Tel: 303/497-3496 Kathy Hillen Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Estimated limits of uncertainty are based upon a statistical analysis of

previously obtained calibration data. These uncertainties are believed to

result solely from sources of random

error as opposed to known systematic

errors.

References—Q-Standards

Standards for the Calibration of

Q-Meters, 50 kHz to 45 MHz,

R. N. Jones, J. Res. Natl. Bur.

Stand. (U.S.), SBC, No. 4, 243

(Oct.-Dec. 1964).

Test No. Items

527 IOC Inductive Q-Standards; 50 kHz-45 MHz, 0.25 jaH to 25 mH

52711C Each Additional Frequency for 527 IOC

Q-Standards (52710C-52711C)

Standards for Q-measurements are maintained at NIST. These are highQ inductors equipped with banana

plug connectors at a spacing of

il 1 inch on centers. These standards

have inductance values of 0.25, 2.5,

i. 25, 250, 2500, and 25,000 jaH, and ef- fective Q-values from 100 to approximately 600. These serve as working

Il standards for calibration of Qstandards of a similar type. Calibration frequencies range from 50 kHz

[Il to 45 MHz. The calibration report inI eludes effective resonating capaci- tance and effective Q. Uncertainties

are of the order of ±0.2 percent for capacitance and 2 percent for Q. Provisions are made for calibrating each

Q-standard at three frequencies; however, adequate assurance of stability

is usually provided by recalibrating

only at the center frequency.

113
53110S-53190S

C. Voltage Measurements

C. 1 DC Voltage Measurements

and Standards

Technical Contacts:

June E. Sims

Tel: 301/975-4238

Richard L. Steiner

Tel: 301/975-4226 Norman B. Belecki

Tel: 301/975-4223

Denise D.

Prather

Administrative and Logistics

Tel: 301/975-4221

Mailing Address: B146 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

531 lOS Special DC Voltage Measurements, by

Prearrangement

53120M Measurement Assurance Program for DC Voltage

53130C First Saturated Standard Cell in a Group

53131C Each Additional Cell 53 HOC Platinum Resistance Thermometer Temperature

Determination for Standard Cell Calibration 53150C Unsaturated Standard Cells 53160C Tests of Solid-State Voltage Reference Standard

(1 Output, 1-10 V)

53161C Each Additional Output

531 SOS Special Handling (Equipment Pickup or Delivery)

53190S Special Handling (Cleaning, Minor Repair, Return

Service Charge)

General Information—DC Voltage

Measurement Standards

The service described in this section

provides for the calibration of stan- dards of direct voltage, saturated and

unsaturated standard cells, and solid- state standards, and for dc voltage

MAP services at the 1.02-volt level. The U.S. Legal Voh is maintained by

monitoring the emfs of several

groups of saturated standard cells in ovens on a weekly basis using the ac Josephson effect. Customer cells are

calibrated by measuring the differ- ence between their emfs and those of

working groups of standard cells us- ing automated systems comprised of

low-level computer-controlled

switches and high-resolution digital

voltmeters.

Figure 13 summarizes the uncertainty of NIST dc voltage measure- ments for the primary standards,

standard cells, and Zener diodes.

Figure 13. Uncertainties of NIST DC Voltage

Measurements

5x10^

108

Z 5x10'

10^

5x106

106

5x 105

-Primary Cells

Zener

Diodes /

- Standard

Cells

10^ DC Voltage

10^

Special DC Voltage Measurements, by

Prearrangement (53110S)

The evaluation, testing, or calibration

of prototype dc voltage standards

and measuring apparatus or unique

voltage measurements are provided

for in this service. These measure- ments are performed only when

deemed reasonable by the appropriate

technical staff and serving the best long-term interests of the client, the

measurement community, and NIST.

114
Measurement Assurance Program

Service (53120M)

This MAP service provides a measurement of the error of dc vohage

measurements in the customer laboratory at the 1.02-volt level, the uncertainty of the results, and an updated

assigned value for the client's refer- ence standards. A transport standard,

which consists of a standard cell en- closure containing four saturated

standard cells, maintaining constant temperature via line and battery

power, is used. It is preferentially

hand-carried between NIST and the

client laboratory, but arrangements

may be made for air shipment. The

standard is calibrated by NIST, the

customer laboratory, and again by

NIST to obtain the required data. The transport standard is capable of

performing at the 0.2- to 0.3-ppm

level of reproducibility when handcarried, 0.5 to 0.8 ppm otherwise.

The measurement uncertainty

achieved in this service contains primarily random errors. The major

components of random error can be

attributed to:

A. Day-to-day fluctuations in temperature-corrected cell emfs

caused by temperature-hysteresis

effects; B. The finite resolution of the

measurement apparatus at both the

client laboratory and NIST;

C. Thermal emfs, unstable with

time, which occur in the measuring

circuit due to room temperature and

humidity changes and drafts; D. Temperature coefficients of

the enclosures as a whole, not compensated for by temperature corrections; E. Lack of resolution or instability of the apparatus used to monitor

the cell temperatures;

F. Slow changes in temperature

gradients or enclosure temperatures

possibly due to atmospheric "pumping" of cool air into the enclosures, or vibration effects on the control

circuitry;

G. Controller instabihty caused

by power-line noise; H. Effects of electrostatic or elec- tromagnetic pick-up on the measuring

system;

I. Detector drift; and

J. Momentary upsets in cell emfs

caused by small electrical currents

passing through the cells. The experimental design described

for making the intercomparison measurements removes the effects of av- erage "left-right" or offset errors. One potentially significant source of

error not corrected for or quantified

in the MAP service is that caused by

scale-factor errors in the instrumentation used to measure the differences

between cell emfs. An error from

this source can be eliminated by using

calibrated instruments and applying

the appropriate calibration corrections to the results. A method for quantifying scale-factor errors can be

provided to MAP service users by

NIST on request.

The transport standard is normally

kept in the client's laboratory for about 4 weeks, as 8 to 12 measure- ment sets are generally required.

Data analysis and issuance of the test report by NIST takes 4 to 5 weeks

following the return of the transfer standards.

If the participating laboratory has a quality instrument that has been accurately calibrated and also has quality

standards, the uncertainty of a single transfer of the unit of voltage using

NIST transport standards is generally

of the order of 0.5 ppm or better. The best achievable long-term uncertainty, resulting from five or more

transfers over an extended time, is of

the order of 0.2 to 0.3 ppm.

In this service, NIST provides detailed instructions for carrying out

the transfer and making the required

measurements. The participant must

have in-house standards and instru- mentation capable of sustained perfor- mance at the 0. 1-ppm level. When a new participant (or group of partici1 15
pants) expresses a desire to use the

voltage MAP service, NIST requests

that a complete description of the

participant's measurement system, in- cluding instruments, standards, wires,

switches, and their use, be sent to the

NIST technical staff. This description

enables NIST personnel to assist in resolving measurement problems by

telephone.

NIST now requires evidence, in the form of control charts, of the ex- istence of a formal quality-control

program in the laboratory as a prerequisite to participation in the ser- vice. This requirement has been

established to enable problems to be

addressed in advance of the transfer and to reduce delays in returning the

standards to NIST.

Saturated Standard Cells (53130C-53140C)

Routine calibrations of saturated stan- dard cells involve the following considerations:

A. Saturated standard cells of the

unshippable type should always be

transported by messenger because

such cells should never be tipped

from an upright position by more

than 45° in any direction. Unshippable saturated cells contained in portable, temperature-regulated en- closures should also be transported

by messenger and with the enclosure

activated or under power, if possible. B. Saturated standard cells of the

shippable type housed in portable

thermoregulated enclosures should be

packed carefully and shipped under

power if possible. Any liquid-in-glass

thermometer mounted in such a device should be removed and pro- vided with additional rigid packing

for protection against breakage. Enclosures having a nominal cell temperature of 28 °C or lower should not be transported during the summer

due to the danger of overheating. Enclosures should not be energized by

using the ac power mains while they

are in shipping containers as heat

from the transformer will cause them

to go over-temperature.

C. Saturated standard cells, which

are maintained continuously at their nominal temperature of use during

shipment, will undergo test starting 1 week after receipt and continue until the cell emfs are sufficiently stable for a report to be issued. This typically takes 4 weeks or less. If such

cells perform abnormally, the owner

will be notified. Arrangements for further testing may be made at that time if desired. Cells will be returned

as soon as possible after calibration. D. Saturated cells arriving at a temperature other than their nominal

temperature of use will be brought to

their use temperature as soon as possible after receipt. Starting 1 month

after they are initially brought to use temperature, daily readings will be

taken to observe the stability of the

cells. When the cells stabilize, 10 daily readings will be taken and aver- aged to assign values to them. This

process will not exceed 90 days with- out special arrangements being made.

E. For an additional fee, the temperature of air bath enclosures for saturated standard cells will be deter- mined using a calibrated NIST platinum resistance thermometer (test 53140C). Daily readings are taken

and reported. The reported cell emfs

are assumed to correspond to the mean of the temperatures measured on the same days as the emf readings were taken. The client must understand that, when this is done, the uncertainties of the reported emfs

include the emf equivalent of the uncertainty of the measured temperatures in terms of the International

Practical Temperature Scale of 1968

as amended in 1975 [Metrologia 12,7

(1976)]. Moreover, estimates of the

uncertainties of any voltage measure- ments made by the client using these

cells as a reference must include cor- responding uncertainties of his own

temperature measurements.

F. NIST accepts cells used in oil baths for calibration in NIST oil baths maintained at 28 and 30 °C. Cells used in oil baths operating at other nominal temperatures can best

1 16
be calibrated using transport stan- dards as in the MAP service. (See

53120M above.)

Calibration uncertainties generally

range from 0.3 to 0.75 ppm. The

stated uncertainties are those of the

NIST-measured average values, i.e., they do not reflect long-term behavior of the cells, transportation effects,

etc.

Unsaturated Standard Cells (53150C)

Unsaturated cells require approximately 3 weeks for a complete cali- bration. The emfs of such cells are read daily for a minimum period of

10 days. These cells are compared

with NIST saturated cells using a precision digital voltmeter to measure

the difference emf directly. The cali- bration uncertainty is 0.005 percent of

the measured voltage unless the cell

is abnormal. If the measured emf

fluctuates unduly or is unusually low,

or if the cell behaves abnormally, the

report of calibration will reflect these

circumstances. Unsaturated cells are not likely to be injured by normal

transportation (mail or express) if they are packed carefully. Because of

the possible hazard from freezing,

shipment during extremely cold

weather should be avoided.

Solid-State Voltage Reference

Standards (53160C and 53161C)

Solid-state voltage standards with

outputs in the range from 1 to 10

volts are calibrated using a self- calibrating automated system which

scales to any multiple up to 10 of

1.018 volts from the emf of a working group of NIST saturated standard

cells. It then measures the difference

between the emf of the standard un- der test and the emf of its own out- put closest in voltage to that of the standard being measured and computes its emf. Measurements are taken daily for 12 to 15 working days

and the mean value of the results reported.

Because of the limited battery life of many commercial standards, special shipping arrangements are advisable and can be made by contacting

the Electricity Division.

Many solid-state standards have

multiple outputs; the outputs to be

calibrated should be specified on the

shipping papers as well as on the pur- chase order to ensure proper testing.

Voltmeter calibrators, multirange

instruments with up to eight decimal

digits of adjustability, are not considered by NIST to be standards and are not to be submitted routinely for cali- bration under this test category. Likewise, NIST will not accept component solid-state devices for routine

calibration. However, new, state-of- the-art devices and instruments may

be accepted for test under special cir- cumstances (see test 531 lOS) at the

discretion of NIST technical staff.

1 17
June Sims at the control console of one of the NIST automated systems for calibrating customers ' voltage sta/idards.

References—Voltage Measurements

and Standards

NBS Measurement Services: Solid- State DC Voltage Standard Cali- brations, B. F. Field, Natl. Bur.

Stand. (U.S.), Spec. Publ. 250-28

(Jan. 1988).

NBS Measurement Services: Standard

Cell Calibrations, B. F. Field, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-

24 (Oct. 1987).

The NBS Josephson Array Voltage

Standard, C. A. Hamilton, R. L. Kautz, F. L. Lloyd, R. L. Steiner,

and B. F. Field, IEEE Trans. lu- strum. Meas., IM-36, 258 (June

1987).

A Sub-PPM Automated One-to-Ten

Volt Measuring System, B. F. Field, IEEE Trans. lustrum. Meas.,

IM-34, 327 (1985).

Volt Transfer Program Instructions,

NBS Internal Document, Unpublished, Revised (1983).

A High-Resolution Prototype System

for Automatic Measurement of

Standard Cell Voltages, D. W.

Braudaway and R. E. Kleinmann,

IEEE Trans. Instrum. Meas.,

IM-23, 282 (1974).

Volt Maintenance at NBS via 2e/h:

A New Definition of the NBS

Volt, B. F. Field, T. F. Finnegan,

and J. Toots, Metrologia, 9, 155

(1973).

Designs for Surveillance of the Volt

Maintained by a Small Group of

Saturated Standard Cells, W. G.

Eicke and J. M. Cameron, Natl. Bur. Stand. (U.S.), Tech. Note 430

(Oct. 1967).

Standard Cells—Their Construction,

Maintenance, and Characteristics,

W. J. Hamer, Natl. Bur. Stand.

(U.S.), Monogr. 84 (Jan. 1965).

118
Voltage Measurements

C.2 AC Voltmeters and Sources

Technical Contacts:

Nile M. Oldham Barry A. Bell

Tel: 301/975-2408 Tel: 301/975-2419

Mailing Address: B162 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 53200S Special Tests of High-Accuracy AC Voltmeters and

Sources, by Prearrangement

Special Tests of High-Accuracy

AC Voltmeters and Sources,

by Prearrangement (53200S)

NIST offers a special-test service for ac voltmeters and sources (calibrators) in the 0.1 -Hz to 1-MHz fre- quency range. Low-frequency

measurements (0.1 to 10 Hz) are made using an NIST-developed "AC

Voltmeter/Calibrator" [Schoenwetter

(1983) and Schoenwetter (1978)],

which contains a high-resolution rms

digital voltmeter (DVM) and both ac and dc voltage calibrators. The

DVM, which is based on a multijunction thermal voltage converter (TVC), is used to characterize a digitally synthesized source at 10 Hz.

This source may then be used to cali- brate test voltmeters at frequencies of

0.1, 0.2, 0.5, 1, 2, 5, and 10 Hz at vol- tage levels between 0.5 mV and 7 V.

The DVM is used as a transfer standard to calibrate test sources at any frequency in the 0.1- to 10-Hz

range. Measurements are normally

made near the full-scale level of the

voltmeter ranges (2, 5, 10, 20, 50 mV,

and 0.1, 0.2, 0.5, 1, 2, 5 V). Because

of its flat frequency response (±40

ppm), the DVM can be used to measure directly the frequency response

of test sources. The estimated uncertainty of measurements made over

the range 0.1 to 10 Hz is less than

200 ppm (0.02 percent).

At higher frequencies a trial ser- vice is offered using an NISTdeveloped wideband automatic

voltage calibration system [Oldham et

al. (1987) and Oldham and Parker

(1987)], which is also based on TVC

techniques. Using this system, an ac

calibrator is characterized and then

used to calibrate ac voltmeters at voltages of 0.25 V to 1 kV from 10 Hz to 1 MHz by direct thermal measurements. A set of inductive voltage

dividers are used to scale a thermally

measured signal to calibrate volt- meters in the range 1 to 250 mV from

10 Hz to 100 kHz.

AC sources (calibrators) are cali- brated in a similar manner; however,

between 1 to 250 mV an rms volt- meter serves as a transfer standard

between a characterized source and

signals from the test calibrator. The estimated uncertainties associ- ated with both measurement systems

are shown in Figure 14. These uncertainties include the random errors en- countered during a typical calibration. The shaded areas represent

voltages and frequencies that are be- ing investigated for future services. An assessment of uncertainties in these areas will be made on an indi- vidual basis. The narrow shaded strip

down to 10 " Hz represents development of a calculable digitally synthesized source at accuracy levels of

5 to 20 ppm.

Prospective clients are encouraged

to submit only those instruments

that are used as transfer standards to

calibrate other instruments and that have long-term stability commensurate with the level of uncertainty

needed.

1 19
53200S

Figure 14. NIST Uncertainties for AC Voltage

Measurements

10^

102

10^

10° o

> 10-1

10-2

10-3

10-^

5-20 ppm

100-200 ppm 20-200 ppm

J I L J I L

10-2 lO-"! 10° 10^ 102 10^ 10" 10^ 106 107 10^ 109 FREQUENCY (Hz)

References—AC Voltmeters and

Sources

A High-Accuracy, 10 Hz-1 MHz Automatic AC Voltage Calibration

System, N. M. Oldham, M. E. Parker, A. Young, and A. G.

Smith, IEEE Trans. Instrum. Meas., IM-36, pp. 883-887 (Dec.

1987).

NBS Calibration System for AC

Voltage, N. M. Oldham and M. E. Parker, Proceedings of the NCSL

1987 Workshop and Symposium,

Denver, CO (July 1987).

AC Voltage Calibrations for the 0.1- Hz to 10-Hz Frequency Range,

H. K. Schoenwetter, Natl. Bur.

Stand. (U.S.), Tech Note 1182

(Sept. 1983).

An RMS Voltmeter/Calibrator for Very Low Frequencies, H. K.

Schoenwetter, IEEE Trans. In- strum. Meas., IM-27, No. 3, 259

(Sept. 1978).

Nile Oldham (standing) and Mark Parker operate the NIST automatic ac

voltage calibration system used to make special tests of customers' highaccuracy voltmeters and sources above 10 Hz.

120
Voltage Measurements

C.3 AC-DC Thermal Voltage and Current

Converters (to 1 MHz)

Technical Contacts:

Joseph R. Kinard

Tel: 301/975-4250 Norman B. Belecki

Tel: 301/975-4223

Denise D.

Prather

Administrative and Logistics

Tel: 301/975-4221

Mailing Address: B146 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items

533 lOS Special AC-DC Measurement Services,

by Prearrangement

53340C AC-DC Thermal Voltage and Current Converters

(1 voltage or current at 1 frequency from 2 Hz to 1 MHz)

53341C Additional Determination at 1 Frequency

(from 2 Hz to 1 MHz)

General Information—Thermal

Voltage and Current Converters

Routine calibrations of thermal

voltage and current converters are no

longer being performed on a scheduled basis. However, to facilitate rapid turnaround, please advise

D. D. Prather at the telephone no./

address cited above before sending

the equipment.

Calibration services for widefrequency range thermal voltage converters, such as John Fluke Model

A55 or HP 11000 series, have been

extended in the NIST Boulder Laboratory to cover frequencies down to 100 Hz with uncertainties as low as 0.05 percent (see tests 53405S53420C). This means thermal converters of this type can be completely

calibrated at NIST Boulder if the

0.05 percent uncertainty is acceptable. Calibration requiring uncertainties less than 0.05 percent in the

range below 1 MHz continue to be

done in NIST Gaithersburg (533 lOS53341C).

Special AC-DC Measurement Services,

by Prearrangement (53310S)

This service provides for the measurement or evaluation of prototype

ac voltage or current standards,

sources, or measurement instrumentation, and for other measurements of

alternating voltage, alternating current, or ac-dc difference not provided

for below, at the discretion of NIST

technical experts. Components used

for ac-dc conversions will generally not be tested unless they show

promise of standards-level behavior.

Even then, such components will only be tested in very limited numbers to explore their possible use for precision measurements.

Special ac-dc difference calibra- tions of appropriate thermal voltage

and thermal current converters are now offered with an uncertainty of

0.8 ppm. This sub-part-per-million

calibration service is the result of an

extensive study of the group of multijunction thermal converters that make up the NIST primary standards. Thermal converters will be accepted

for calibration with the 0.8 ppm uncertainty providing their performance, including stability and

square-law response, is compatible

with the NIST standards and highprecision comparator system. In general, the sub-ppm uncertainty is available for voltages from 2 to 12 V,

currents from 5 to 20 mA, and fre- quencies from 30 to 10 kHz. As in the case of the other special ac-dc

difference calibrations with reduced

uncertainty, an additional cost and a longer-than-usual turnaround time at NIST are required. Prospective

clients are asked to contact Joseph

Kinard, phone (301) 975-4250, to dis- cuss the requirements and arrange- ments related to this service.

121
AC-DC Thermal Voltage and Current

Converters (Up to 1 MHz)

(53340C-53341C)

This service covers the calibration of

thermal voltage and current converters, ac shunts, and primary ther- moelements covering the ranges 2 Hz

to 1 MHz, 1 mA to 20 A, and 0.5 to 1000 V. These are used to make measurements of alternating current and

voltage in terms of direct current standards of voltage and resistance

and are calibrated at NIST by comparison with similar NIST devices.

Ordinarily only ac-dc transfer stan- dards and thermal converters of 0.05 percent or better rated accuracy are accepted for test. AC-DC difference

tests consist of determinations of the

differences between the current or

voltage, required to give the same re- sponse (output) of the transfer stan- dard for alternating current and for the average of the two directions of

direct current. Tests are recom- mended at rated voltage or current on each range up to the highest fre- quency of interest. For 1000-V

ranges, a second test at 600 V is recommended because these ranges

may be affected by self-heating. In addition to the high-frequency tests, an ac-dc difference test (ordinarily at 20 Hz) is recommended for one

range, to verify the low-frequency

accuracy. Thermoelements have a low-frequency limit, below which

they fail to integrate properly. The

ac-dc difference may approach 0.02

percent at frequencies ranging from

ab(Dut 5 Hz, for most low-range ther- moelements, to about 60 Hz, for some

thermoelements with ratings above

1 A. This low-frequency ac-dc

difference is nearly the same for all ranges of a multirange converter in which a single thermoelement is used

with shunts or multipliers. For convenience, usually a low-voltage or

current range is chosen for the test. Unless the test points have been

firmly established in prior practice,

the user is strongly advised to contact

the appropriate NIST technical staff prior to submission of the standards to NIST for calibration.

Thomas Lipe operates the automated comparator

system for ac-dc difference measurements.

Ill
Table 14: AC-DC Difference Calibration Service

Frequency: 2-5 5-20 20-20k 20-50 50-100 0.1-0.5 0.5-1 Hz Hz Hz kHz kHz MHz MHz

Voltage

Limits (V)

Current

Limits (A)

50 100

0.05 0.05

1000

13 [a]

1000

16

1000 100 100

Uncertainty (parts per million)

Multirange TVC's > 100 V

< 100 V 200 100 50 70 100

inn Coax Single Range

TVC's > 100 V 20 30 50

5 V <X< 100 V 200 100 15^ 25 40 100 200 < 5 V 200 100 20 30 50 100 200

Speciall"!

5 V <X< 100 V 10 TCC's > 5 A

50 mA < X < 5 A

< 50 mA 200 100

100

50

50

15070

70

5 A at 20 Hz, increasing to 18 A from 100 Hz to 5 kHz; 16 A above

5 kHz. 20 A shunts are calibrated at less than rated current. The lower uncertainty applies at the crossover frequencies. Uncertainties may be increased if the ac-dc differences are large or affected by self- heating or other instability.

'-l 20 ppm from 20 Hz to 100 Hz, 15 ppm at 100 Hz and above.

'''' Normally available by prearrangement for coaxial, single-range TVC's

between 100 Hz and 20 kHz. An additional cost and a longer turnaround

time at NIST are required.

An Investigation of the Uncertainly

of the NBS Thermal Voltage and

Current Converters, F. L. Hermach, Natl. Bur. Stand. (U.S.),

NBSIR 84-2903 (April 1985).

The Practical Uses of AC-DC Transfer Instruments, E. S. Williams,

Natl. Bur. Stand. (U.S.), Tech.

Note 1166 (Nov. 1982).

Thermal Voltage Converters and

Comparators for Accurate AC

Voltage Measurements, E. S. Williams, J. Res. Natl. Bur. Stand.

(U.S.), 75C (Dec. 1971).

Thermal Voltage Converters for Accurate Voltage Measurements to 30

Megacycles Per Second, F. L. Hermach and E. S. Williams, Trans. AlEE (Communica. Elect.)

79, 1, 200 (July 1960).

Thermal Converters as AC-DC

Transfer Standards for Current and

Voltage Measurements at Audio

Frequencies, F. L. Hermach, J. Res. Natl. Bur. Stand. (U.S.), 48, 121 (1952).

References—AC-DC Thermal

Converters (to 1 MHz)

Multijunction Thermal Converters as the NBS Primary AC-DC Transfer

Standards for AC Current and

Voltage Measurements, F. L. Hermach, J. R. Kinard, and J. R.

Hastings, IEEE Trans. Instrum. Meas., IM-36, No. 2, 300 (June

1987).

A Dual-Channel Automated Comparator for AC-DC Difference

Measurements, E. S. Williams and

J. R. Kinard, IEEE Trans. Instrum. Meas., IM-34, No. 2, 290 (June

1985).

123
53405S-53445S

C Voltage Measurements

w C.4 RF-DC Thermal Voltage and Current

Converters (100 Hz-1 GHz)

Technical Contacts:

Gregorio Laura J. Wray Kathy Hillen Rebuldela Tel: 303/497-3706 Administrative

Tel: 303/497-3561 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items Test No. Items 53405S Special Tests of AC Thermal Voltage Converters,

by Prearrangement

53410C Low-Frequency TVC Calibration at One Frequency

Selected from Those Given in Table 15 at Rated

Voltage in the Range 0.1-50 V

5341 IC Additional Frequency Selected from Table 15 for Same TVC as in 534 IOC

53412S Same as 53410C, Except Customer Designates a Single Frequency (in Same Frequency Range) Other

Than Those Given in Table 15 5341 3C Low-Frequency TVC Calibration at One Frequency

Selected from Those Given in Table 15 at Rated

Voltage in the Range 50-200 V

53414C Additional Frequency Selected from Table 15 for Same TVC as in 5341 3C

53415S Same as 53413C, Except Customer Designates a Single Frequency (in Same Frequency Range) Other

Than Those Given in Table 15

53420C High-Frequency TVC Calibration at One Frequency

Selected from Those Given in Table 16 at Rated

Voltage in the Range 0.1-7.5 V

53421C Additional Frequency Selected from Table 16 for Same TVC as in 53420C

53430S Peak-to-Peak Detector Calibration at One Frequency

Selected from Those Given in Table 17 at 1.2 V

Applied RF Voltage

5343 IS Additional Frequency for Peak-to-Peak Detector in Test 53430S

53440S Special Tests of RF Micropotentiometers, by

Prearrangement

53441C RF Micropotentiometer Calibration for Percent RF-DC Difference, at Any Single Frequency within

0.05-900 MHz and at Rated Voltage

(Range 1-100,000 /xV)

53445S Special Calibration of RF Micropotentiometer

(Output Voltage Range, 200 to 200,000 jitV at Frequency Range, 0.05 to 1000 MHz) with Reduced

Limits of Uncertainty

General Information—RF-DC Thermal

Voltage and Current Converters,

100 Hz to 1 GHz (53405S-53445S)

Services are available for three types

of electromagnetic voltage measuring

devices: (1) Thermal Voltage Converters (TVC's), (2) Peak-to-Peak

Detectors, and (3) Voltage Comparators and one type of electromagnetic

generating device: RF Micropotentiometers.

124
53405S-53445S

Many years of experience in cali- bration of micropots and TVC's have

shown that these are very stable devices even for periods of up to 10

years. Thus, in most cases, a 2-year or longer recalibration cycle is rec- ommended. An exception might be

the micropots which operate below

100 jLtV. Assurance of device stability can

be obtained by intercomparison of

micropots or TVC's with others

where voltage ranges overlap. For

example, a 0.3- to 1-V TVC can be

compared with a 1- to 3-V TVC at

1 V, etc. TVC calibrations requiring uncertainties less than 0.05 percent below

1 MHz are performed in NIST

Gaithersburg. See tests 533 lOS53343C.

RF Voltage Comparators (53405S)

Special tests are performed on rf voltage comparators using TVC's and

micropotentiometers from 100 kHz to

1 GHz at voltages ranging from 10 mV to 20 V. Several calibration options are available to the customer.

Therefore, consultation by telephone

or written correspondence is sug- gested before the comparator is submitted for calibration.

Thermal Voltage Converters

(53410C-53421C)

The thermal voltage converter (TVC) category also includes other

devices using thermal detectors such

as Rawson rf voltmeters, thermal

transfer standards, rf voltage stan- dards, and ac-dc transfer standards.

Most converters have rf-dc differ- ences within ±0.01 percent of zero at

1 MHz and below. All converters having previous calibration history

that are submitted for recalibration

should be evaluated at 1 MHz and re- sults compared to prior data. If the

difference is negligible, no further

calibrations are usually necessary below 1 MHz.

The quantity measured by this cali- bration service is the rf-dc difference,

defined as the percentage difference

between the rf and dc voltages re- quired to produce the same thermocouple output, e.g.,

rf-dc difference (%)=^

^^'~^''^jx 100.

Services available for low-frequency

TVC's without a built-in "T" connector are given in Table 15. For highfrequency TVC's with a built-in "T"

connector, the services available are given in Table 16. Calibrations above

100 MHz are performed only on the new high-frequency thermal voltage converters with a "T" connector

incorporated in the converter housing. The measurement reference

plane is at the Type "N" male output

connector.

Table 15: Specifications and Estimated Uncertainties for Low-Frequency TVC Services

Recommended

Frequencies

RF Voltage

Range

(V)

Estimated

Limits of Uncertainty*

(±%)

0.03, 0.1, 0. 1 to 200 0.05

0.3, 1 kHz

3 and 10 MHz 0.1 to 200 0.1 30 MHz 0.1 to 200 0.2 100 MHz 0.1 to 200 1.0

* No rf-dc differences greater than ±20 percent will be reported. This normally limits the calibrations to 100 MHz and below.

Table 16: Specifications and Estimated Uncertainties for High-Frequency TVC Services

RF Voltage Estimated

Frequency Range Limits of Uncertainty*

(MHz) (V) (±%)

10 0.1 to 7.5 0.1 30 0.1 to 7.5 0.2

100, 200, 300, 400 0.1 to 7.5 1 500, 600, 700 0.1 to 7.5 1 900, 900, 1000 0.1 to 7.5 1

* No rf-dc differences greater than ± 20 percent will be reported.

125
53405S-53445S

Peak-to-Peak Detectors (53430S)

Measurements on peak-to-peak detectors are performed from 100 kHz to 500 MHz and are referenced to the center of a GR 874 "T" connector. A

50-kHz ac signal is applied instead of

dc. The services available are specified in Table 17.

Table 17: Specifications and Estimated Uncertainties for Peak-to-Peak Detector Services

Frequency

(MHz)

Applied RF Voltage

for "0" Detector Output

(Vp_p)

Estimated Limits

of Uncertainty

(%)

0.1, 0.3, 1.0 1.2 0.15

3, 10 1.2 0.20 30 1.2 0.30 50 1.2 0.60

100, 200, 300, 400, 500 1.2 1.10

RF Micropotentiometers

(53440C-53445S)

Radiofrequency micropotentiometers

are usually calibrated at their nominal

rated output voltages. Frequencies

suggested for a normal calibration are

5, 100, 300, 400, 500, 700, and 900

MHz. Special arrangements may be

made for calibrations up to 1000

MHz with reduced limits of uncertainty.

Radiofrequency micropotentiometers having resistive elements greater

than 10 milliohms in combination

with thermoelement housings be- tween 5 and 100 mA, usually have rf- dc differences within ± 1 percent at 5 MHz. Since the rf-dc difference ap- proaches zero below 5 MHz, calibra- tions at 50 kHz and 5 MHz would

suffice to determine interpolated

points of interest between 50 kHz and

5 MHz, with no appreciable loss of

accuracy. Estimated uncertainties are shown in Table 18.

An rf-dc difference of about ±5

percent at 1 MHz usually results from

a combination using a 1-milliohm ele- ment with thermoelement housings

between 5 and 100 mA. Interpolation

below 1 MHz is not recommended in this case.

Table 18: Specifications and Estimated Uncertainties for RF Micropotentiometer Calibrations

Any Frequency RF Voltage Estimated

within Band Range Limits of Uncertainty*

(MHz) (juV) (±%)

0.05 to 100 1 to 100,000 2 100 to 500 1 to 100,000 3 500 to 900 1 to 100,000 5

* For rf-dc differences greater than ± 20 percent, estimated limits of

uncertainty are larj^er than those listed.

The rf-dc difference is defined as the percentage difference between the

rf and dc voltages required to pro- duce the same thermocouple output,

with the resistive elements terminated

in 50 ohms, e.g.,

rf-dc difference (%) =

V,,

XlOO.

As a special service, rf micropotentiometers with output voltage greater

than 200 jiiV can be calibrated from

0.05 to 1000 MHz, with reduced limits of uncertainty varying from ±0.2

percent to ±2 percent. This uncertainty is dependent on frequency, out- put level, and the rf-dc difference vs. frequency response. For further details, consult with the technical contact cited at the beginning of this section.

126
References—RF-DC Voltage and

Current Converters (100 Hz-1 GHz)

NBS RF Voltage Comparator, L. D.

Driver, F. X. Ries, G. Rebuldela,

Natl. Bur. Stand. (U.S.), NBSIR

78-871 (Dec. 1978).

High-Frequency Microvolt Measurements, F. X. Ries and

G. Rebuldela, ISA Proc, 18, 1, 37.2.63, Instrum. Soc. of Amer.,

Res. Triangle Park, NC (Sept.

1963).

Thermal Voltage Converters for Accurate Voltage Measurements to 30 Megacycles Per Second, F. L. Hermach and E. S. Williams, Trans. AIEE, Pt. 1, Commun.

Elect., 72, 200 (July 1960).

Thermal Converters as AC-DC

Transfer Standards for Current

and Voltage Measurements at Audio Frequencies, F. L. Hermach,

J. Res. Natl. Bur. Stand. (U.S.), 48, 121 (1952).

Accurate Radio Frequency Microvoltages, M. C. Selby, Trans. AIEE, Pt. 1, Commun. Elect., 72,

158 (May 1953).

127
53500S-53540S

C Voltage Measurements

f C.5 Data Converters

Technical Contacts:

T. Michael Barry A. Bell Souders Tel: 301/975-2419

Tel: 301/975-2406

Mailing Address: B162 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 53500S Special Data Converter Services, by Prearrangement

535 IOC A/D or D/A Converter, Linearity Errors at 1024

Points, 10-Bit Correction Coefficients, and Superposition Errors 53520C A/D or D/A Converter, Differential Linearity Errors at 2(N-1) Points (N = No. of Bits) 53530C A/D Converter, Equivalent RMS Input Noise

53540S A/D or D/A Converter, Offset and Gain Errors

Relative to U.S. Legal Volt

Data Converters (53500S-53540S)

NIST maintains a calibration service

for static testing of high-resolution

(12 to 18 bit) analog-to-digital (ADC)

and digital-to-analog (DAC) converters. Routine measurements, for which

calibration reports are issued, are made of the static parameters listed below. However, NIST has recently

developed the capability to measure

the dynamic response of ADC's to well-defined, programmable input

voltage steps characteristic of typical

input signals. These dynamic measurements can be made as a special

test. Until further analysis of systematic and random errors of the test procedure is completed and until additional operating experience is obtained, the customer will receive the

test results with appropriate error

analysis, but no calibration report will be issued. There is no standard data- converter terminology, but NIST

uses the following definitions of

parameters to describe its calibration

service:

A. Linearity Error: The differ- ence between the actual and ideal levels of the static input/output characteristic after corrections have been

made for offset and gain errors. B. Differential Linearity Error: The difference between the actual

and the ideal separation between adjacent levels. C. Offset Error: The difference

between the actual and the ideal levels, measured at the most negative

level of the input/output characteristic. Due to practical considerations,

this definition is modified to the sec- ond most negative level (i.e., with the

least significant bit (LSB) on).

D. Gain Error: The difference

between actual and ideal levels, measured at the most positive level of the

input/output characteristic, after cor- rection for offset error. Again, in practice, a defining level is chosen

slightly below the one stated here. E. Equivalent RMS Input Noise:

The rms value of the effective inter- nal noise of an ADC, referred to its input terminals. In these definitions, the specified

levels for DAC's are taken to be the

discrete output levels, and for ADC's

the analog input levels are those at which the digital output transitions between adjacent codes occur. In this latter case, the transition levels are defined by the upper digital code of

the transition in question.

The principal error parameters are

usually those of linearity and differential linearity. Nevertheless, gain and

offset errors may also be measured

when appropriate, and the equivalent rms input noise of ADC's can be

128
measured as well, provided it has ap- proximately a Gaussian distribution. Determination of monotonicity in DAC's and missing codes in ADC's

is not generally performed since these

tests require excessive measurement

time for high-resolution converters. These characteristics can often be in- ferred, however, from the available

linearity data. Sensitivity of the vari- ous parameters to changes in temperature and power supply voltage, for example, is also not generally deter- mined.

Description of Static Tests: A. Linearity: For the linearity

test, all 1024 digital codeword combinations of the 10 most significant bits are measured. Errors contributed by

the remaining, less significant bits are generally insignificant, a premise

which is tested during the calibration process. The data are numerically

processed to determine the maximum,

minimum, and rms errors of the 1024

tested codes, and to determine, on a least-squares basis, individual correction coefficients for the 10 most sig- nificant bits. The residuals from the

computation of correction coefficients are a direct measure of the converter's superposition errors. These

are computed as well. B. Differential Linearity: Differential linearity errors are measured at 2(N-1) major codeword transitions, for an N-bit converter. C. Offset & Gain: In general, converter offset and gain measure- ments are not required, since it is common practice to provide adjustable trimmer circuits, which are

periodically set to suit individual sys- tem requirements. However, accurate

voltage measurements directly trace- able to legal standards can be pro- vided if required. Offset and gain

errors are measured directly by set- ting the test converter to the designated code and measuring the input

(or output) voltage by direct comparison with a transfer standard cali- brated by NIST.

D. RMS Input Noise: The equivalent rms input noise of ADC's can be measured either as an average

value over the entire full-scale range

of the converter, or as a function of

codeword, at 64 randomly selected

points. The measurement technique

relies upon the assumptions that the

noise has a Gaussian distribution and

that, at a given sampling rate, sucessive values are uncorrelated. The

validity of these assumptions is tested prior to performing the measurements.

E. Specification for Test Converters: To be compatible with the

NIST data converter test set, test units must conform to the following

general specifications:

1. Nominal resolution from 12 to

18 bits,

2. Conversion rate of at least 10 kHz,

3. Binary coding format, including

binary sign-magnitude, offset bi- nary, 2's complement, I's complement, and complemented versions of these,

4. TTL compatibility,

5. Voltage ranges of 0-5 V, ±5 V;

0-10 V, ±10 V,

6. Maximum error, including offset and gain, not to exceed 500 ppm.

Systematic Uncertainties:

The estimated limits of the systematic

uncertainties in measuring the various converter error parameters are summarized in Table 19 for a ±10 V

range.

129
53500S-53540S

Table 19: Specifications and Estimated Uncertainties for Data Converter Calibrations

Parameter

Estimated Systematic Uncertainty

DAC's ADC's

Linearity Error

Differential Linearity Error

Offset Error<''' Gain Error'-" RMS Input

Noise'^'

2.7 ppm +0.04 LSB

3.2 ppm +0.04 LSB

3 ppm

6 ppm

4.7 ppm +0.16 LSB

5.2 ppm +0.16 LSB

3 ppm +0.07 LSB

6 ppm +0.13 LSB

-100%; +(20% + 10 /xV) Noise introduced by the Test Set is approximately

30 nV/(Hz)"- in a 1-MHz bandwidth

Measured upon special request only, if no adjustable trimmers are provided for these parameters. Since the effective bandwidth of the test converter is generally un- known, the noise contribution from the test set cannot be determined.

Therefore, only an upper limit can be accurately placed on the noise measurements. Random errors of the measurement

process necessarily include random

variations in the test converter and

are, therefore, individually evaluated

for each test. Nevertheless, measure- ments on very stable (check standard) converters indicate the random errors contributed by the test set itself are

substantially less than the respective

systematic uncertainties listed in the

table. Figure 15 shows the estimated

systematic uncertainty of the NIST

data converter test system for resolutions from 12 to 18 bits. Dynamic Tests of ADC's:

Dynamic errors in ADC's are defined

as any deviations from the static transfer characteristic resulting from

prior exercise (i.e., previous changes

in input). The test converter is exercised with stepped input changes typical of the conditions of actual use. The dynamic errors are measured in terms of the changes in the test converter's code transition levels result- ing from prior exercise. A more

complete description of the dynamic

testing now provided for ADC's on a Special Test basis is provided in Souders et al., "An Automated Test

Set for the Dynamic Characterization

of A/D Converters" (see references).

Figure 15. Uncertainty for NIST Data Converter Test System for Resolutions from 12- 18 Bits

10'

10' cB

CDO

c3

10"

ntegral Linearity Error

Differential Linearity Error

12 13 14 15 16

Resolution in Bits

Preparation of Test Boards:

In general, the customer is responsible for mounting the integrated cir- cuit, hybrid, or modular test converters on suitable test boards, and

for providing all required trimmer

circuits, voltage references, input or output amplifiers, recommended

power supply decoupling capacitors,

and connectors for interfacing to the

input/output lines. Fully self- contained converters need only be

fitted with the necessary interfacing connectors. In so doing, the customer

gains significant performance advantages while at the same time saving

the additional fee that would otherwise be charged by NIST for per- forming this service. Highperformance converters are often sus- ceptible to small changes in grounding.

17

130 I
routing of dynamic signal lines, ca- pacitive loading, etc. Particularly

with ADC's, signal dynamics are

quite important, even for static test- ing, because the converter itself al- ways operates at high speeds. When

mounted by the customer, the test converter and its support circuitry can be laid out to simulate more

closely the way it will be used, ac- cording to the specific manufacturer's

recommendations. Therefore, the test results should more closely describe

the converter's in situ performance.

Detailed type and wiring requirements for the interfacing connectors

are available upon request.

References—Data Converters

An Automated Test Set for the Dynamic Characterization of A/D

Converters, T. M. Souders, D. R.

Flach, and T. C. Wong, IEEE

Trans. Instrum. Meas., IM-32,

No. 1, 180 (Mar. 1983).

A Calibration Service for Analog-toDigital and Digital-to-Analog Converters, T. M. Souders, D. R. Flach, and B. A. Bell, Natl. Bur.

Stand. (U.S.), Tech. Note 1 145

(July 1981). (Provides a complete

description of the calibration ser- vice.)

A Technique for Measuring the Equivalent RMS Input Noise of

A/D Converters, T. M. Souders

and J. A. Lechner, IEEE Trans.

Instrum. Meas., IM-29, No. 4, 251

(Dec. 1980).

A 20-Bit + Sign Relay Switched

D/A Converter, T. M. Souders

and D. R. Flach, Natl. Bur. Stand.

(U.S.), Tech. Note 1 105 (Oct.

1979). (Describes the reference

standard used in the calibration ser- vice.)

A High-Speed Low-Noise 18-Bit Digital-to-Analog Converter, H. K. Schoenwetter, IEEE Trans. In- strum. Meas., IM-27, No. 4, 413

(Dec. 1978).

131
54110S-54131C

f Precision Ratio Measurements

m D.I Inductive Dividers

Technical Contacts:

Bruce F. Norman B. Denise B.

Field Belecki Prather

Tel: 301/975-4230 Tel: 301/975-4223 Administrative and Logistics

Tel: 301/975-4221

Mailing Address: B146 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20399-0001

Test No. Items

541 1 OS Special Ratio Measurements and Tests of Inductive

Voltage Dividers, by Prearrangement

54120C Inductive Voltage Dividers—(Single Frequency,

Voltage To Be Specified, Each Setting of 3 Most

Significant Dials) 541 2 IC Additional Frequency Points 54130C Inductive Voltage Dividers—(Single Frequency,

Voltage To Be Specified, Each Setting of Most

Significant Dial Only)

541 3 IC Additional Frequency Points

Special Ratio Measurements and Tests

of Inductive Voltage Dividers, by

Prearrangement (541 lOS)

This service category provides for the measurement and/or evaluation

of prototype ratio devices and inductive voltage dividers based on new

principles, and for unique ratio measurements at the highest accuracy

levels, such as the determination of

the ratios of Hamon resistance transfer devices or Silsbee-type voltage ratio standards. Such measurements are undertaken at the discretion of NIST

technical staff and only when the

need for them can be clearly demonstrated.

Inductive Voltage Dividers

(54120C-54131C)

Inductive voltage dividers (decade

transformer dividers) are accepted for calibration only at 60, 100, 400, 1000,

5000, and 10,000 Hz. The most significant dial only can be calibrated at 15 and 20 kHz.

Calibration voltages may be specified up to 100 V or the manufacturer's specified limit, whichever is lower. The largest contribution to in- stability in undamaged inductive

voltage dividers is wear or dirt in the

decade switches. Variable contact re- sistance in these switches sometimes

affects the stability of voltage-ratio

measurements to a significant extent but is most evident by its effect on

the phase angle. When a decade in- ductive voltage divider exhibits large

changes in phase angle for repeated

measurements after the switches have

been disturbed, the divider should no

longer be considered satisfactory for use as a voltage-ratio reference stan- dard. Inductive voltage dividers that use pushbutton switching or incorporate a resistive divider as a fine adjustment usually are not accepted for

calibration. Corrections to the separate decades

of an inductive divider, in general,

cannot be simply combined. However, the correction to a step setting

of one of the higher decades usually

is independent of the setting of the

lower decades. The effects of stray

impedances must be corrected by

connecting the case to the divider at one point, and unless otherwise specified, the case will be connected to one of the "common" terminals, typically marked "GRD," "Case GND,"

or "Case GRD." Decade inductive

voltage dividers are calibrated at NIST at room temperature (22 to 24 °C) by comparison with a twostage, three-decade transformer of

known ratios.

132
References—Inductive Dividers

American National Standard for Decade Transformer Dividers

(Voltage Type), ANSI CI 00,

1-1972 Amer. Natl. Stand. Inst., New York, NY (Jan. 1972).

Instructions for the Use of the NBS

Reference Inductive Divider,

Wilbur C. Sze, Natl. Bur. Stand.

(U.S.), NBSIR, unpubhshed (1970).

(Available from NIST.)

Two-Stage, Guarded Inductive

Voltage Divider for Use at 100

kHz, D. H. Hamon and T. L. Zaf,

ISA Transactions, 9, 3, Instrum. Soc. of Amer., Res. Triangle Park,

NC (1970).

Comparator for Calibration of Inductive Voltage Dividers from 1 to 10 kHz, W. C. Sze, ISA Transactions,

6, 4, Instrum. Soc. of America,

Res. Triangle Park, NC (1967).

133
54210C-54214S

#^ Precision Ratio Measurements

mm^m D.2 Resistive Dividers

Technical Contacts:

Martin Misakian Richard J. Edward F. Robert E. (DC Measurements) Van Brunt Kelley Hebner, Jr. Tel: 301/975-2426 (60-Hz Mea- (Pulsed Mea- Tel: 301/975-2403

surements) surements)

Tel: 301/975-2425 Tel: 301/975-5826, 5146

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

For 54210C-54211S:

[Attn: M. Misakian, Bldg. 220, Room B351]

For 54212C-54213S:

[Attn: R. J. Van Brunt, Bldg. 202, Room 167]

For 54214S:

[Attn: E. F. Kelley, Bldg. 202, Room 137]

Test No. Items

542 IOC Resistor and Resistive Dividers, Total Resistance or Voltage Ratio, Two Direct Voltage Levels between

10 kV and 150 kV

5421 IS Special Tests of Resistor and Resistive Dividers at Direct Voltage Levels, by Prearrangement

542 12C Resistor and Resistive Dividers at 60 Hz, Voltage

Ratio and Phase Angle, between 10 kV and

100 kV rms

542 13S Special Tests of Resistor and Resistive Dividers at 60 Hz, by Prearrangement

542 14S Special Tests of Resistor and Resistive Dividers

Under Pulsed High-Voltage Conditions, by

Prearrangement

Resistor and Resistive Dividers, DC

Measurements (54210C-54211S)

A calibration service is maintained at NIST to specify the dc voltage ratio of resistive dividers. The routine cali- bration service is available for applied

voltages from 10 kV to 150 kV. The

calibrations are performed with a measurement system which has an

uncertainty of ±0.01 percent of the

voltage ratio. To assure adequate sensitivity at the lowest applied voltage

levels, calibrations are performed routinely only on dividers with ratios of

100,000:1 or smaller. The routine cali- bration service is also restricted to di- viders with a low-resistance element

of 10,000 ohms or less. Resistive dividers are acceptable

for calibration only if they are nearly corona free at the rated operating

voltage and are designed to have

small temperature and voltage coefficients. Specifically, a device is not

generally suitable for calibration by

NIST if these coefficients produce a change in the ratio of ±0.1 percent over the normal range of operating

voltages. At a given voltage, dividers

should not exhibit instabilities in their

ratio value in excess of 0.005 percent.

NIST staff can provide some assis- tance in the identification of other

calibration laboratories capable of

certifying the response of less accurate dividers.

Resistor and Resistive Dividers, 60-Hz

Measurements (54212C-54213S)

Resistive dividers of sufficient quality

to be considered as transfer standards

are calibrated at 60 Hz for applied

voltages between 10 kV and 100 kV

rms. High-voltage dividers may per- form satisfactorily as standards under

dc voltages but do not perform well

enough to be considered as standards

when excited by 60-Hz voltages. The

design of an ac divider requires special features, beyond those of a dc di- vider. In particular, ac dividers

designed to be used as transfer stan- dards may have to be equipped with

external shielding to minimize the ef- fects of capacitive coupling to sur- rounding objects.

134
If the device is not properly

shielded, the effects of proximity to surrounding objects and pickup from

high-voltage conductors can intro- duce large uncertainties into the measured value of the divider ratio. In such cases, the measurement of the

ratio for one configuration would not

necessarily be vahd for another configuration. Consequently, a meaningful calibration of the device is difficult or impossible.

Therefore, we recommend that the

following two preliminary proximity

tests be performed before an ac di- vider is submitted for test to deter- mine the suitability of the device as a

transfer standard. Place the divider

about 2.0 m from a vertical ground

plane as measured from the center of

the device. Energize the divider to some safe high-voltage level and measure the divider ratio. Repeat the

measurement with the same applied

high voltage but with the vertical ground plane (or divider) moved into a position 1.2 m from the center of

the divider. If the measured divider

ratio changes by 0.1 percent or more,

the device has excessive capacitive

coupling and is not suitable as a

transfer standard.

To test for pickup, remove the

high-voltage connection to the top of

the divider and then connect the top

of the divider to ground with a thin

wire. Measure the output voltage of

the divider under these conditions

both with and without the highvoltage source energized. If the re- sulting change in the output voltage

exceeds 0. 1 percent of the expected

output voltage when the high voltage

is connected to the divider, then

again there is excessive coupling indi- cating that the device is not suitable

as a transfer standard.

High-voltage ac dividers sent to NIST are first subjected to tests like those described above before any

measurements are attempted. If such

tests show variations in the measured

ratio of more than 0. 1 percent for

either proximity or pickup, then no

further tests will be performed and

the device will be returned. The cus- tomer will be charged for the cost of

these tests. NIST calibration of voltage trans- formers at 60 Hz is generally more

accurate than its calibration of di- viders at the same frequency. Therefore, customers having a requirement

for a calibrated divider may find it advantageous to use a voltage trans- former as the transfer standard and to use that transformer to calibrate the

divider in their own facilities. Routine tests are carried out for voltages between 10 kV and 100 kV

rms and are performed with a measurement system having an uncertainty of 0.05 percent in the

determination of the ratio and ±0.5

milliradian in the determination of the

phase angle.

Resistor and Resistive Dividers,

Pulsed High-Voltage Conditions

(54214S)

Resistive divider ratios are also deter- mined under pulsed high-voltage conditions. All pulsed measurements are by prearrangement. Determinations

employ special-design pulse dividers

and calibrated Kerr cells as reference

standards. A variety of pulses may be

applied to simulate the conditions un- der which the divider will be used. Calibrations are made at selected voltage intervals from 20 kV to 300

kV as requested and up to 500 kV

with certain pulse shapes. The typical

uncertainty is ±3 percent of the

voltage ratio although smaller uncertainties can occasionally be reported

as a special test. Shipping:

Dividers can be hand-carried or shipped to NIST. Shipped dividers

should be packaged in sturdy reusable

containers. The design of many highvoltage dividers makes them vulnerable to shear-type forces, so provisions

should be made to minimize the

likelihood of damage due to such

forces when the device is in the shipping container.

135
References—Resistive Dividers

High-Voltage Divider and Resistor

Calibrations, M. Misakian, Natl. Bur. Stand. (U.S.), Tech. Note

1215 (July 1985).

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R. A.

Bullock, Natl. Bur. Stand. (U.S.),

NBSIR 77-1933 (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand.

(U.S.), NBSIR 77-1317 (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park,

J. Res. Natl. Bur. Stand. (U.S.),

66C, No. 1, 19 (Jan.-Mar. 1962).

1 36
Precision Ratio Measurements

D.3 Capacitive Dividers

Technical Contacts:

Robert E. Richard J. Edward F. Hebner, Jr. Van Brunt Kelley

Tel: 301/975-2403 (60-Hz Mea- (Pulsed Measurements) surements) 301/975-2425 Tel: 301/975-5826, 5146

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

For 54310S:

[Attn: R. J. Van Brunt, Bldg. 202, Room 167]

For 54311S:

[Attn: E. F. Kelley, Bldg. 202, Room 137]

Test No. Items

5431 OS

5431 IS

Special Tests of Capacitive Dividers at 60-Hz,

by Prearrangement

Special Tests of Capacitive Dividers Under Pulsed High-Voltage Conditions, by Prearrangement

Capacitive Dividers, 60-Hz Measurements (54310S)

Determinations of capacitive divider

ratios at 60-Hz ac employ the same

equipment used for the calibration of

ac resistive dividers (see 542 12C).

The same limitations pertain to shielding (proximity and pickup ef- fects). The NIST measurement sys- tem imposes a negligible burden on

the divider if its output voltage is 100

volts or less. Otherwise, the burden is equivalent to a 1000-picofarad capacitor.

Capacitive Dividers, Pulsed

High-Voltage Conditions (54311S)

Determinations of capacitive divider

ratios under high-voltage pulse conditions employ special-design pulse di- viders and calibrated Kerr cells as reference standards. A variety of

pulses may be applied to simulate the

conditions under which the divider

will be used. Calibrations are made at selected voltage intervals from 20 kV

to 300 kV as requested and up to 500

kV with certain pulse shapes. The

typical uncertainty is ±3 percent of

the voltage ratio although smaller uncertainties occasionally may be negotiated.

References—Capacitive Dividers

High-Voltage Divider and Resistor

Calibrations, M. Misakian, Natl. Bur. Stand. (U.S.), Tech. Note

1215 (July 1985).

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R.A.

Bullock, Natl. Bur. Stand. (U.S.),

NBSIR 79-1933 (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand.

(U.S.), NBSIR 77-1317 (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park,

J. Res. Natl. Bur. Stand. (U.S.),

66C, No. 1, 19 (Jan.-Mar. 1962).

137
5441 OS

D. Precision Ratio Measurements

D. 4 Mixed Dividers

Technical Contacts:

Edward F. Robert E. Kelley Hebner, Jr. Tel: 301/975-5826 Tel: 301/975-2403

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

References—Mixed Dividers

Evaluation of a Multimegavolt Impulse Measurement System, R. E. Hebner, D. L. Hillhouse, and R. A.

Bullock, Natl. Bur. Stand. (U.S.),

NBSIR 79-1933 (Nov. 1979).

Calibration of High-Voltage Pulse

Measurement Systems Based on the

Kerr Effect, Natl. Bur. Stand.

(U.S.), NBSIR 77-1317 (Sept.

1977).

Special Shielded Resistor for HighVoltage Measurements, J. H. Park,

J. Res. Natl. Bur. Stand. (U.S.),

66C, No. 1, 19 (Jan.-Mar. 1962).

Test No. Items 54410S Pulse Voltage Measuring Systems, Including Kerr Cells

Mixed Dividers (54410S)

A mixed divider is one constructed of

resistors and capacitors. Ratios of

mixed-voltage dividers are deter- mined under pulsed high-voltage conditions. Determinations employ

special-design pulse dividers and cali- brated Kerr cells as reference stan- dards. A variety of pulses may be

applied to simulate the conditions un- der which the divider will be used. Calibrations are made at selected

voltage intervals from 20 kV to 300

kV as requested and up to 500 kV

with certain pulse shapes. The typical

uncertainty is ±3 percent of the

voltage ratio although smaller uncertainties can occasionally be reported

as a special test.

138
^ Precision Ratio Measurements

a D.5 Voltage and Current Transformers

Technical Contacts:

William E. John D. Ramboz

Anderson (Current Transformers)

(Voltage Tel: 301/975-2434

Transformers)

Tel: 301/975-2423

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

For 54510C-54513C:

[Attn: W. E. Anderson, Bldg. 202, Room 167]

For 54520C-54522C:

[Attn: J. D. Ramboz, Bldg. 220, Room B165]

Test No. Items

545 IOC Voltage Transformer, Ratio & Phase Angle, at 60 Hz

on 1 Range, 1 Secondary Voltage, 1 Burden

Primary Vrms <150 kV

5451 IC Same as 545 IOC, Additional Similar Transformer at Same Time

545 12C Same as 545 IOC and 5451 IC, Additional Burden or Range

545 13C Same as 54510C-54512C, at Each Additional

Secondary Voltage

54520C Current Transformer, Ratio & Phase Angle, 1 Range

at 1 Frequency and 1 Burden, Secondary Currents

0.5, 1, 2, 3, 4, 5 A, Primary Current Not Over 8000 A

5452 IC Current Transformer, Ratio & Phase, 1 Secondary

Current, Additional Combination of Range,

Frequency, and Burden, Primary Current Not

Over 8000 A

54522C Current Transformer, Ratio & Phase at Each

Additional Secondary Current, Same Combination

of Range, Frequency, and Burden as 54520C

or 54521C

54600S Special Tests of Dividers and Transformers, by

Prearrangement

Voltage Transformers

(54510C-54513C)

NIST provides routine services for the measurement of complex voltage

ratios (magnitude and phase angle) of

transformers for primary voltages up

to 150 kV and for secondary voltages

above 50 V, subject to some constraints as to the maximum physical

size of the device. Results of these

routine tests are reported with an uncertainty of ±0.03 percent for ratio and 0.3 mrad (1 mrad = 3.438 min)

for phase angle. If the test conditions

and the device under test warrant,

special tests with smaller uncertainties can be performed. These special tests may require an extra fee. The customer must specify the sec- ondary voltage and the secondary

burden for each transformer or for each range of a multirange trans- former. Ambiguity can be avoided if the impedance and power factor, or

the resistance and reactance, are

specified rather than the volt-ampere

rating of each burden. The customer

should note that the NIST calibration

system represents a minimum burden

of 1000 pF for routine calibrations. The customer should give some care

to the specification of a burden

recognizing that the use of the trans- former with a burden different from

that used in the calibration can result

in significant error. Calibrations of voltage transformers are performed routinely only at 60 Hz. Measurements are made with one side of both the primary and sec- ondary windings connected to ground.

NIST does have some capability to perform measurements at voltages,

frequencies, and burdens outside of

the ranges described above. Calibrations can occasionally be provided at these nonroutine test points as a special test for an increased fee.

1 39
Current Transformers

(54520C-54522C)

Normally NIST calibrates only current transformers of high quality for use as reference standards. The NIST

equipment is designed to test current transformers with a rated secondary

current of 5 A, with test points chosen to be one or more of the following values: 0.5, 1, 2, 3, 4, 5 A.

Routine tests are carried out at 50,

60, and 400 Hz. For measurements at 50 or 60 Hz, the resuhs are generally

reported with an uncertainty of

±0.01 percent in ratio and ±0.1

mrad in phase angle. For measure- ments at 400 Hz, the reported uncertainty is ±0.03 percent in ratio and

±0.3 mrad in phase angle.

The customer must specify the test frequency, the secondary currents,

and the secondary burdens for each

transformer or for each range of a multirange transformer. Current

transformers should be tested with

burdens equivalent to those which

are imposed when the device is used

as a transfer standard. Routine cahbration using the burdens specified in the American National Standards Institute (ANSI) Standard C-57.13 is not recommended unless these burdens are subsequently used in the cus- tomer's factory or laboratory. Large

errors can result if the values of ratio and phase angle obtained with an ANSI recommended burden are used

for the transformer when it is con- nected to a different burden.

Preferably the burden should be

specified in terms of the measured

resistance and inductance. These val- ues should include the effects of the

leads used to make a connection to the transformer secondary. An alter- native, which is sometimes feasible, is to submit the transformer together

with its normal leads and connected

burden for calibration as a unit. If neither of the above are possible, the

burden may be stated in terms of the

voltampere product and the power

factor of the secondary circuit at the

test frequency. For reference, it

should be noted that the test equipment regularly used at NIST represents a minimum test burden of about

0.03 ohms with a inductance of about

10 jLtH. Because of contact resistance and

current rectification, loose or dirty

primary and secondary terminations

may affect the measurement results. These surfaces should be tight and

clean when the transformer is shipped

to NIST to minimize this source of

error. Unless otherwise specified, current transformers are demagnetized prior

to calibration. If it is desired to have

a transformer tested as submitted

(without demagnetization), this re- quirement should be stated on the

purchase order and NIST staff should

be informed by telephone before the

transformer is shipped.

Many current transformers are not designed to be used as transfer stan- dards, and most of these do not re- quire calibration at NIST. NIST staff can provide some assistance in the as- sessment of the appropriateness of the

device for NIST calibration and in the identification of alternative cali- bration sources. If NIST is required

to perform laboratory measurements

to determine whether or not a partic- ular device can be calibrated, a charge for the cost of these

measurements will be made.

Special Tests of Dividers and

Transformers (54600S)

The Electrosystems Division maintains an active program of research

and development in the area of electrical measurements at high-voltage

levels. For this reason, NIST often is able to provide measurement support

for high-voltage devices other than

those listed above in this section. Special tests will generally be conducted

by NIST, if the following criteria are met:A. The requested tests are fully

developed and documented.

140
54510C-54600S

B. There is a significant technical or economic justification for traceability of the test on the item to national standards. C. There has not been a routine or recurrent need for the test.

References—Voltage and Current

Transformers

A Calibration Service for Voltage

Transformers and High-Voltage

Capacitors, W. E. Anderson, Natl. Bur. Stand (U.S.), Spec. Publ. 250-

33 (June 1988).

An Electronic Ratio Error Set for Current Transformer Calibrations, R. L. Kahler, IEEE Trans. In- strum. Meas., IM-28, No. 2, 162

(June 1979).

A Wide-Range High-Voltage Capacitance Bridge with One-ppm Accuracy, O. Petersons and W. E. Anderson, IEEE Trans. Instrum. Meas., IM-24, No. 4, 336 (Dec.

1975).

Wide-Band Two-Stage Current

Transformers of High Accuracy,

T. M. Souders, IEEE Trans. In- strum. Meas., IM-21, No. 4, 340

(Nov. 1972).

A Wide-Range Current Comparator

System for Calibrating Current

Transformers, T. M. Souders,

IEEE Trans. Power Appar. Syst.

PAS-90 No. 1, 318 (Jan.-Feb.

1971).

141
55110S-55141C

Phase Measurements

E, / Phase Meters and Standards

Technical Contacts:

Raymond S. Turgel

Tel: 301/975-2420

Barry A. Bell

Tel: 301/975-2419

Mailing Address: B162 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 55110S Special Tests of Phase Standards and Related

Instruments, by Prearrangement

55120C Phase Meters—One Combination of Input Voltages

(0.5 V to 100 V rms) at one Frequency (2 Hz to 50 kHz)—the Input Voltage Ratio Shall Not

Exceed 10 55121C Phase Meters—Each Additional Combination of

Input Voltages (0.5 V to 100 V rms) at the Same or at a Different Frequency (2 Hz to 50 kHz)—the Input

Voltage Ratio Shall Not Exceed 10 55130C Phase Meters—One Combination of One Input

Voltage (0.5 V to 120 V rms) and One Input Current

(1 to 5 A rms) at One Frequency (2 Hz to 5 kHz)

55131C Phase Meters—Each Additional Combination of One

Input Voltage (0.5 V to 120 V rms) and One Input Current (1 to 5 A rms)

55 HOC Phase Meters—One Input Voltage (0.5 V to 120 V

rms) and Another Input Voltage (0.5 V to 100 V rms)

at One Frequency (2 Hz to 5 kHz)

55141C Phase Meters—Each Additional Combination of One

Input Voltage (0.5 V to 120 V rms) and Another

Input Voltage (0.5 V to 100 V rms) at the Same or at a Different Frequency (2 Hz to 5 kHz)

arrangements for these tests should be

discussed with NIST; prior arrange- ments are essential.

Phase Meters (55120C-55141C)

NIST has a capability for characterizing audio frequency phase meters over a frequency range of 2 Hz to 50

kHz. The standard used is a microcomputer-based system that synthesizes two sinusoidal voltages by means of digital techniques. The two

signals are displaced relative to one

another by a precisely known phase

angle. Phase angles can be set with a resolution of 0.002 degree up to 5 kHz and 0.005 degree above 5 kHz.

The amplitude of the two output sig- nals can be varied independently

from 0.5 volt to 100 volts rms. At

power frequencies, one of the signals can be a current from 0.5 to 5 amperes. The uncertainty in setting the

standard is less than ±0.01 degree

below 5 kHz and increases to ±0.04

degree at 50 kHz if the two output

signals have the same amplitude. For

unequal outputs, this uncertainty in- creases to ±0.015 degree and ±0.090

degree respectively, if the amplitude

ratio is less than 10:1. Although the accuracy of the

phase angle standard does not rely on

the stability of the frequency, the

generated output, which can be

varied in steps of 1 Hz, is locked to a crystal-controlled frequency synthesizer. Figure 16 shows a plot of the total estimated uncertainty of the NIST

Phase Angle Calibration Standard as a function of frequency for two limit- ing amplitude ratios.

Special Tests of Phase Standards

and Related Instruments,

by Prearrangement (55110S)

NIST will perform special-test phase

angle measurements on phase angle

generators, quadrature detectors, and

phase bridge-networks. Restrictions

apply, and technical limitations and

142
Figure 16. Estimated Total Uncertainties of tlie NIST

Phase Angle Calibration Standard

0.100

Dl

0) D

0.080 -

0.060-

•§ 0.040

5 0.020

0.000

0.002

/s Amplitude Ratio 10;1 \/

III ---^^.>. tquai AmpiiTuaes

P—" 1 11 1 5 10 15

Output Frequency (KHz)

30 50

Special requirements for this service

are as follows:

A. The voltage inputs of phase

meter to be tested must have

impedances such that the current is limited to a few milliamperes at any

applied voltage requested. Current in- puts must have impedances low

enough so that the compliance

voltage does not exceed 2 volts. B. NIST will test the instrument

in the as-received condition, without

making any zero or gain adjustments. C. In some cases, the response of

phase meters involves significant time

constants; in these cases, readings will be taken 30 seconds after the setting

of the standard.

D. For given voltage and fre- quency settings, at least three readings will be taken at each specified

phase angle. The order of readings

will be randomized.

E. The experimental data are fit- ted to a mathematical model from

which the phase meter response can be predicted. From the closeness of

fit to the model, it can be determined

whether observed deviations from the

predicted values are significant. F. Each phase meter will be oper- ated under power for at least 2 hours

before test data are taken. G. Meters that are not in operating condition upon receipt at NIST

will be returned to the owner with- out repairs.

References—Phase Meters

NBS Measurement Services: Phase

Angle Calibration Services, R. S. Turgel, J. M. Mulrow, and D. F. Vecchia, Natl. Bur. Stand. (U.S.),

Spec. Publ. 250-26 (May 1988).

Phase Meter Calibrations at NBS,

R. S. Turgel, J. Res. Natl. Bur.

Stand. (U.S.), 93, No. 1, 53-59 (Jan.

1988).

Precision Calibration of Phase Meters, R. S. Turgel and D. F. Vecchia, IEEE Trans. Instrum. Meas., IM-36, No. 4, 915-922 (Dec.

1987).

NBS 50-kHz Phase Angle Calibration

Standard, R. S. Turgel, Natl. Bur.

Stand. (U.S.), Tech. Note 1220

(Apr. 1986).

A Wideband Transconductance Amplifier for Current Calibrations,

O. B. Laug, IEEE Trans. Instrum. Meas., IM-34, No. 4, 639-643 (Dec.

1985).

A Precision Phase Angle Calibration

Standard for Frequencies Up to 50

kHz, R. S. Turgel, IEEE Trans. Instrum. Meas., IM-34, No. 4, 509- 516 (Dec. 1985).

NBS Phase Angle Calibration Standard, R. S. Turgel, N. M. Oldham,

G. N. Stenbakken, and T. H.

Kibalo, Natl. Bur. Stand. (U.S.),

Tech. Note 1144 (July 1981).

A High-Performance Phase-Sensitive

Detector, L. A. Marzetta, IEEE

Trans. Instrum. Meas., IM-27, No.

4, 460-464 (Dec. 1978).

High-Precision Audio-Frequency

Phase Calibration Standard, R. S. Turgel and N. M. Oldham, IEEE

Trans. Instrum. Meas., IM-27, No.

4, 460-464 (Dec. 1978).

143
55210C-55230S

E Phase Measurements

I E.2 Very-High-Frequency Omnidirectional

Range (VOR) Measurements

Technical Contacts:

Neil T. Larsen William E. Kathv Hillen

Tel: 303/497-3711 Little Administrative

Tel: 303/497-5479 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Test No. Items 55210C VOR Bearing-Angle Indicators, 12 Bearing Angles

Over the Range 0 to 330 Degrees

552 lie Calibration of VOR Bearing-Angle Indicator at Each

Additional Angle

55220C VOR Generators, 12 Bearing-Angle Equivalent

Signals Over the Range 0 to 330 Degrees

55221C Calibration of VOR Generator at Each Additional

Angle

55230S Special VOR Tests

VOR Measurements—General

Information

The NIST calibration services for VOR air navigation signals are described in detail in VOR Calibration

Service, NBS Technical Note 1069

(see references).

Two services are offered to sup- port the calibration of VOR (Veryhigh-frequency Omnidirectional

Range) instruments. NIST has de- signed and built a standard VOR au- dio generator, used to calibrate

unknown VOR bearing-angle indicators, and a standard VOR bearingangle indicator, used to calibrate

unknown audio generators. Direct

generation or measurement of stan- dard VOR rf signals are not a part of

the service. Quality control of the NIST stan- dards is accomplished by using each

to measure the other. As a result of

these measurements, the uncertainty

of a calibration of either a generator

or a bearing-angle indicator is given

by the following statement, which is part of the calibration report:

"The assigned values of VOR bearing angles are the nominal bearings

from 0 to 360 degrees in increments

of 0.01 degrees. The overall uncertainty of these values has been esti- mated from test data at bearings from

0 degrees to 360 degrees at 30-degree

increments. Thus, each of the nominal bearings has been assigned an

overall uncertainty of ±0.0017

degrees, based on estimated bounds

of 0.00065 degrees on the systematic

error and a computed standard error of 0.00105 degrees."

VOR Bearing-Angle Indicators

(55210C and 55211C)

An unknown bearing-angle indicator

is calibrated by connecting its input

to the output of the NIST standard

generator. The generator provides a composite audio signal that is the sum

of two signals, each 1 volt rms (±1

percent) in amplitude. The first signal

is a 30-Hz sinusoid and represents the

variable phase signal recovered from

the VHF carrier. The second is the

frequency-modulated 9960-Hz subcarrier. NIST will calibrate at any set of

12 bearing angles specified by the

customer (if not specified, at 30- degree intervals over the inclusive

range 0 to 330 degrees).

144
VOR Generator (55220C and 55221C)

Only certain commercial VOR generators are suitable for calibration. They should provide a composite au- dio signal of nominally 1 volt rms, per tone. They must have a short- term phase jitter of less than 10 nsec. The modulation index for the 9960-

Hz subcarrier must be equal to 16 ±

1 percent. Most commercial generators do not meet these requirements

and can best be calibrated by submitting a bearing-angle indicator for cali- bration instead. This can then be used

to transfer the NIST calibration to the unknown generator with some

loss of accuracy. An uncertainty statement for this transfer has not been developed due to lack of his- tory. NIST will calibrate at any set of 12 bearing-angle equivalent signals

corresponding to bearing-angles

specified by the customer (if not

specified, at 30-degree intervals over

the inclusive range 0 to 330 degrees).

Special VOR Tests (55230S)

The NIST standard bearing-angle

indicator lends itself to the measure- ment of audio frequency periodic

waveforms through the use of sampling techniques and time series analysis. It has been used for the accurate measurement of phase angles between

two sinusoids. Special tests of this na- ture may be provided by prearrange- ment. The uncertainty depends upon

the frequency; at 30 Hz it is about

0.0006 degrees (3 standard deviations).

References—VOR Measurements

VOR Calibration Services, N. T. Larsen, D. F. Vecchia, and G. R. Sugar, Natl. Bur. Stand. (U.S.),

Tech. Note 1069 (April 1985).

Fourier Transformation of the Nonlinear VOR Model to Approximate

Linear Form, D. F. Vecchia, Natl. Bur. Stand. (U.S.), Tech. Note

1021 (June 1980).

145
56110S-56210M

F. Power and Energy Measurements,

Low-Frequency

Technical Contacts:

Andrew J. Robert E. Secula Hebner, Jr. Tel: 301/975-2416 Tel: 301/975-2403

Mailing Address: B344 Metrology, National Institute of

Standards and Technology, Gaithersburg, MD 20899-0001

Shipping Address: National Institute of Standards and

Technology, 1-270 at Quince Orchard Road, Gaithersburg, MD 20899-0001

[Attn: A. J. Secula, Bldg. 220, Room B165]

Test No. Items

561 1 OS Special Tests of AC-DC Wattmeters, by

Prearrangement

56120C Wattmeter Calibrations at Power Frequencies

5612 IC Each Additional Determination of Correction of Same Meter at 50/60 Hz

56200C Watthour Meter, Initial Two Determinations of Percentage Registration of Same Meter at 50/60 Hz

5620 IC Each Additional Determination of Percentage

Registration of Same Meter at 50/60 Hz

56202C Initial Two Determinations of Percentage

Registration of One or Two Meters Run

Simultaneously with the First (56200C)

56203C Each Additional Determination of Percentage

562 lOM Measurement Assurance Program for Watthour Meters

Power and Energy Measurements,

Low-Frequency (56110S-56210M)

Only portable standard wattmeters

and watthour meters (rotating stan- dards and electronic types) are ac- cepted for test. If necessary, the meters should be cleaned or adjusted

by the customer before they are shipped to NIST. NIST does not adjust meters and does not knowingly

begin tests of faulty meters.

The test conditions must be specified by the customer. These include

the current and voltage ranges to be

tested, the frequency, the applied

voltages, the applied currents, and

the power factors. Values of these

parameters which are available for routine testing are summarized in Table 20.

Table 20: Available Values of the Parameters for Routine Wattmeter and Watthour Meter Testing

Parameter Available Values

Voltage (V)

Current (A)

69 110 220 440

115 230 460

120* 240* 480

125 250 500

130 260 520

277 600

0.50 2.50 7.50 25

0.75 3.00 10.00 30

1.25 3.75 12.50 37

1.50 4.00 15.00 40

5.00*

Power Factor

Frequency (Hz)

1.0* 0.5* lagging

0.5* leading

50**

60* 400**

* Available values for Measurement Assurance Program (MAP) measurements.

** Tests at 50 and 400 Hz are limited to voltages of 240 V or less and

currents of 5 A or less.

If necessary, measurements can sometimes be made at other values of

these parameters. These would, however, be considered special tests. Separate, specific arrangements and a higher fee will be charged than for a routine calibration. Unless otherwise specified, the duration of a test run on a wattmeter is approximately 100 seconds. For a watthour meter, the test run duration

is approximately 100 seconds for unity power factor and approximately

200 seconds duration for 0.5 power

factor. Prior to the calibration, the

146
56110S-56210M

meters are energized for between 1 and 4 hours at rated voltage and current on one range. A calibration consists of at least two sets of measure- ments taken over a minimum period

of 2 days.

For wattmeters, the values of the

reported corrections (in watts) generally have uncertainties of ±0.05 per- cent of the full scale range in volt-amperes. For watthour meters,

the reported values of the percentage

registration generally have uncertainties of ±0.05 percent of the indicated

value. Special, higher accuracy tests can be arranged for an additional fee. The uncertainties for power or en- ergy measurements in these special

tests may be as low as ±0.01 percent

if the short-term standard deviation

of the device under test is appropriately small. For the highest accuracy,

voltages are limited to 120 V and

currents to 5 A.

Wattmeter calibrations at other

than power frequencies are considered Special Tests and must be ar- ranged on an individual basis. The

following limitations apply:

A. Instruments must have separate voltage and current input terminals.B. The instrument must have a self-contained power indicator, or provide a direct current signal which

is proportional to power, or provide an output frequency (TTL compatible) which is proportional to the

power.

C. Measurements are generally

limited to sinusoidal signals at fre- quencies between dc and 100 kHz.

Signal levels should not exceed 240 V

and 5 A.

D. Instruments will be tested in the as-received condition, and test uncertainties will be based in part on

the performance of the instrument

during the test. The Measurement Assurance Pro- gram for electric energy is designed

to evaluate the performance of en- ergy-measuring systems at the cus- tomer's laboratory. An NIST-owned,

transport standard watthour meter of

known stability is measured by NIST.

It is then shipped to and measured by

the customer, and shipped back to NIST. NIST analyzes the data and

provides a report to the customer in- dicating the total uncertainty of his measurement. This procedure enables

the customer's standards to be measured relative to NIST standards

without the downtime encountered

when the customer's standards are shipped to and calibrated by NIST.

In addition, and more important to those who calibrate standard

watthour meters, the NIST MAP

standard can be used by customers to evaluate their measurement process in a convenient and cost-effective way.

The uncertainty of a MAP includes

the effects of the long-term and

short-term instabilities of the NIST

calibration system, the customer's cal- ibration system, and the transport

standard. Typically, the uncertainty

in a well-controlled comparison

ranges between ±0.03 percent and

±0.05 percent.

The Electricity Division of the

Center for Electronics and Electrical

Engineering maintains an active pro- gram of research and development in the area of electric power and energy

measurements. This program often

enables NIST to provide measure- ment support for watt and watthour

meters beyond that listed in this section. Special tests will generally be

conducted when the following conditions prevail:

A. The requested tests are fully

developed and documented.

B. There is a significant technical or economic justification for

traceability of the test on the item to national standards. C. There has not been a routine or recurrent need for the test.

147
56110S-56210M

Andrew Secula uses the N1ST automated power and energy measurement

system to calibrate customers' wattmeters and watthourmeters.

References—Power and Energy

Measurements, Low Frequency

Digitally Synthesized Power Calibration Source, N. M. Oldham, O. B. Laug, and B. C. Waltrip, IEEE

Trans. Instrum. Meas., IM-36, No.

2, 341 (June 1987).

NBS Wideband Sampling Wattmeter,

G. N. Stenbakken, O. B. Laug,

A. G. Perry, B. A. Bell, and T. H.

Kibalo, Natl. Bur. Stand. (U.S.),

Tech. Note 1221 (May 1987).

A Wideband Sampling Wattmeter,

G. N. Stenbakken, IEEE Trans. Power Appar. Syst., PAS-103, No.

10, 2919 (Oct. 1984).

A Calibration Service for Wattmeters

and Watthour Meters, J. D. Ramboz and R. C. McAuliff, Natl. Bur.

Stand. (U.S.), Tech. Note 1179

(July 1983).

A Measurement Assurance Program

for Electric Energy, N. M.

Oldham, Natl. Bur. Stand. (U.S.),

Tech. Note 930 (Sept. 1976).

Transfer of the Kilowatthour, S. R. Houghton, IEEE Trans. Power

Appar. Syst., PAS-94, No. 4, 1232

(July-Aug. 1975).

Sampling Techniques for Electric

Power Measurement, R. S. Turgel,

Natl. Bur. Stand. (U.S.), Tech.

Note 870 (June 1975).

A Current Comparator System to Establish the Unit of Electrical Energy at 60 Hz, K. J. Lentner,

IEEE Trans. Instrum. Meas.,

IM-23, No. 4, 334 (Dec. 1974).

148
61110S-61190S

7.

Microwave Measurements

G. 1 Power Meters, RF and Microwave

Technical Contacts r

Ronald A. Ginley

Tel: 303/497-3634

Denis X. LeGolvan

Tel: 303/497-3210

Kathy Hillen Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328.

Test No. Items 61110S

61111S

61120S

61121S

61122S

61123S

61124S

61125S

61126S

Effective Efficiency and Reflection Coefficient of Coaxial Power Meters at Specified Frequency in Range 0.1 to 10 MHz

Each Additional Frequency for 61110S

Calibration Factor, Effective Efficiency, Efficiency

Factor, and Reflection Coefficient of Coaxial

Power Meters at 10, 50, and 100 MHz

Calibration Factor, Effective Efficiency, Efficiency Factor, and Reflection Coefficient of Coaxial

Power Meters at 100, 500, and 1000 MHz

Calibration Factor, Effective Efficiency, Efficiency

Factor, and Reflection Coefficient of Coaxial

Power Meters at 10, 50, 100, 500, and 1000 MHz

Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 50-MHz Intervals within 1-2 GHz

Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 100-MHz Intervals within 2-4 GHz

Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 200-MHz Intervals within 4-8 GHz

Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 200-MHz Intervals in the Range 8-12.4 GHz

Test No. Items

61127S Effecfive Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 250-MHz Intervals in the Range 12.4-18 GHz

61128S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Coaxial Power Meters at 1-GHz Intervals in the Range 1-18 GHz

61140S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 6 Frequencies (2.6, 2.86, 3.0, 3.25, 3.55, and 3.95 GHz) within 2.6-4 GHz (WR284)

61141S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular- Waveguide

Power Meters at 100-MHz Intervals within

4.0-5.8 GHz (WR187)

61142S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 100-MHz Intervals within

6.0-8.0 GHz (WR137)

61143S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 200-MHz Intervals within

7.0-10.0 GHz (WR112)

61144S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 200-MHz Intervals within

8.2-12.4 GHz (WR90)

61145S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 250-MHz Intervals within

10.0-15.0 GHz (WR75)

61146S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at 250-MHz Intervals within

12.4- 18.0 GHz (WR62)

61147S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at a Specified Frequency within

18-26.5 GHz (WR42)

61148S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters at a Specified Frequency within

26.5-40 GHz (WR28)

61155S Effective Efficiency, Efficiency Factor, and

Reflection Coefficient of Rectangular-Waveguide

Power Meters of Specified Frequency within 94-96 GHz (WRIO)

61190S Special Microwave and RF Power Measurement

Services, by Prearrangement

149
Power Meters, RF and Microwave

(61110S-61190S)

The principal emphasis is on those

calibrations and other tests requiring

such accuracy as can be obtained

only by direct comparison with NIST

standards. However, in order to maintain efficient utilization of specialized equipment and skilled personnel, when workload permits NIST

may calibrate devices requiring lesser accuracy but suitable for working

standards in a plant or laboratory.

Also, upon request, special measure- ments may be made. Inquiries should

describe clearly the measurement desired and indicate the scientific or economic basis for the requirement.

Thermistor-type bolometer units have shown adequate stability over

long periods of time (approximately

10 years) and warrant long recalibration intervals. Two- or three-year

recalibration intervals are recom- mended once the stability of a bolometer unit has been verified. Thermoelectric power-meter sensor

units and other power meter/power

sensor units are calibrated only as a

special measurement service on an

at-cost basis. Assistance is available for applying

published, technically valid measure- ment techniques in lieu of previously

available NIST calibration services

for coaxial and waveguide calorimeters, power meters, and bolometer

coupler units. The attainable limits of

measurement uncertainty using these

techniques are comparable to those of

the previously available calibration

services for these devices.

The calibration reports give the

amplitude of the reflection coefficient

and either the effective efficiency, ef- ficiency factor, or the calibration fac- tor depending on the type of sensor and frequency range.

Definitions:

Calibration results are reported in the

following units: Effective Efficiency

The effective efficiency tj,. is the

ratio of the bolometrically substi- tuted dc power in the bolometer

unit to the net cw rf microwave

power absorbed by the bolometer unit. Bolometrically Substituted dc

Power

The bolometrically substituted dc

power is the change in dc (or au- dio frequency) bias power re- quired to maintain the resistance

of the boloriieter element at a constant value following the application of rf or microwave

power.

Calibration Factor, Kb

The calibration factor is the ratio of the bolometrically substituted

dc power in the bolometer unit to the cw rf microwave power

incident upon the bolometer unit.

Efficiency Factor

TE sensor-power meter units: Efficiency factor (mW/V) is the

ratio of the net rf microwave

power absorbed by the sensor head to the dc voltage at the

recorder output of the meter on

the 10 mW range. Reflection Coefficient Amplitude,

|r|

The reflection coefficient amplitude is the ratio of the reflected wave voltage amplitude to the

incident wave voltage amplitude.

The reflection coefficient amplitude is included in the Report of

Calibration for all power measurements. All calibrations are performed under typical ambient

laboratory conditions at 23 °C,

and an atmospheric pressure of

approximately 8.4 +0.2x10'' Pa

at Boulder, Colorado. Services at ambient conditions other than

these are not provided. Also, the

power applied to any device be- ing calibrated does not exceed 10 mW.

150
Coaxial Power Meters and Sensors (61110S-61127S)

Only bolometer units designed for low-frequency operation will be cali- brated below 100 MHz. Most TE

sensor units can be calibrated below

100 MHz.

Specify frequency in range 0.1 to 10 MHz for special low-frequency

bolometer units (Test No. 61 11 IS). Values for rj^ and | F | are calculated

from voltage and resistance measurements.

i?e = (Pdc)/(Prf), where Prf=VVR,.,

where Rp is the parallel equivalent

resistance and Pj^ is the bolometrically substituted dc power in the

bolometer. The uncertainty in measuring Tje is ±0.3 percent.

Measurements are made at the fol- lowing frequencies:

Range

10-100 MHz

100-1000 MHz

1-2 GHz

2-4 GHz

4-8 GHz

8-12.4 GHz

12.4-18 GHz

Frequency or Interval

10, 50, & 100 MHz

100, 500, & 1000 MHz

50-MHz intervals 100-MHz intervals 200-MHz intervals 200-MHz intervals 250-MHz intervals Measurement of the output power

from the reference port on TE power

meters can also be made.

The estimated limits of uncertainty

in effective efficiency and calibration

factor will vary from approximately

1.0 to 2.0 percent depending on the

frequency and the characteristics of

the unit being calibrated such as con- nector type, reflection coefficient,

and repeatability.

Waveguide Power Meters and Sensors (61140S-61155S)

Measurements of effective efficiency,

efficiency factor, and reflection coefficient are made for various waveguide sizes as follows:

Frequency Measurement Wave- Range Frequency or guide (GHz) Interval WR284 2.6-4.0 6 frequencies: 2.6, 2.85, 3.0, 3.25, 3.55, 3.95 GHz

WR187 4.0-5.8 100-MHz intervals WR137 5.8-8.0 100-MHz intervals WR112 7.0-10.0 200-MHz intervals WR90 8.2-12.4 200-MHz intervals WR75 10.0-15.0 250-MHz intervals WR62 12.4-18.0 250-MHz intervals WR42 18-26 Specify frequency

WR28 26.5-40 Specify frequency

WR22 33-50 Not available WR19 40-60 Not available WR15 50-70 Not available WRIO 94-96 Specify frequency

Effective efficiency is measured for bolometer units only. Efficiency fac- tor is measured for TE sensor-power

meter units only. The estimated limits of uncertainty in effective efficiency

will vary from 1 to 3.5 percent depending on the frequency and the

characteristics of the unit being cali- brated.

151
References—Power Meters, RF and

Microwave

WR-10 Millimeter Wave Microcalorimeter, M. Weidman and P. Hudson, Natl. Bur. Stand. (U.S.),

Tech. Note 1044 (June 1981).

A Semiautomated Six-Port for Measuring Millimeter-Wave Power and

Complex Reflection Coefficient, M.

Weidman, IEEE Trans. Micro.

Theory Tech., MTT-25, 12 (Dec.

1977).

Performance Characteristics of an Automated Broad-Band Bolometer

Unit Calibration System, E. Komarek, IEEE Trans. Micro.

Theory Tech., MTT-25, 12 (Dec.

1977).

Theory of UHF and Microwave

Measurements Using the Power

Equation Concept, G. Engen, Natl. Bur. Stand. (U.S.), Tech. Note 637

(Apr. 1973).

Application of an Arbitrary Six-Port

Junction to Power Measurement

Problems, G. Engen and C. Hoer,

IEEE Trans. Instrum. Meas., IM21, 470 (Nov. 1972).

WR-15 Microwave Calorimeter and

Bolometer Unit, M. Harvey, Natl. Bur. Stand. (U.S.), Tech. Note 618

(May 1972).

Accurate Microwave High-Power

Measurements Using a Cascaded

Coupler Method, K. E. Bramall, J. Res. Natl. Bur. Stand. (U.S.), 75C,

Nos. 3 and 4, 185 (July-Dec. 1971).

A Method of Determining the Mismatch Correction in Microwave

Power Measurements, G. Engen,

IEEE Trans. Instrum. Meas.,

IM-17, 4 (Dec. 1968).

Bolometric Microwave Power Cali- bration Techniques at the National

Bureau of Standards, R. F. Desch

and R. E. Larson, IEEE Trans.

Instrum. Meas., IM-12, 1 (June

1963).

A Bolometer Mount Efficiency Measurement Technique, G. Engen,

J. Res. Natl. Bur. Stand. (U.S.),

65C, 113 (Apr.-June 1961).

A Transfer Instrument for the Inter- comparison of Microwave Power

Meters, G. Engen, IRE Trans. In- strum. Meas. 19, 202 (Sept. 1960).

A Refined X-Band Microwave Microcalorimeter, G. Engen, J. Res.

Natl. Bur. Stand. (U.S.), 63C, 77

(1959).

152
Microwave Measurements

a G.2 Attenuators, RF and Microwave

Technical Contacts:

John R. Juroshek Keith C. Roe Kathy Hillen

Tel: 303/497-5362 Tel: 303/497-3365 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 61210S Coaxial Fixed and Variable Attenuators, Frequency

Range 10 MHz to 18 GHz, Attenuation 0 to 60 dB

6121 IC Coaxial Fixed and Variable Attenuators, Measured at 30 MHz, Attenuation 0 to 120 dB

61215C Waveguide Circular (Below CutofO (Piston)

Attenuator, Coaxial Connector, Measured at 30 MHz, Attenuation 0-140 dB (Total Insertion Loss)

61220S Special Attenuation Measurements in Range 30 kHz

to 10 MHz, GR 874 Connectors, 0-10 dB

61230S Variable Rectangular Waveguide Attenuators, Attenuation Difference, Specify Frequencies for Waveguide Sizes WR28, WR42, WR62, WR90,

WR112, WR137, WR187, 0-50 dB

61240S Special Attenuation Measurements of Three-Port and

Two-Port Devices at 1.25 MHz, 0-6 dB

61250S Special Attenuation Measurements, by

Prearrangement

Attenuators, RF and Microwave

(61210S-61250S)

Specific attenuation measurements

currently available are listed below.

Measurements not listed may possibly

be provided (61250S) if sufficient ad- vance notice is given and resources

permit. The cost of such services

must be negotiated and will, in general, be higher than other established

services. Consultation by telephone

or written correspondence is suggested. Often a measurement tech- nique can be suggested that will permit the customer to perform his calibrations in-house with appropriate

reference to other NIST-supported

standards.

Fixed and Variable Coaxial Attenuators (61210S and 61211C)

Coaxial fixed and variable attenuators

are measured on the NIST Dual Six- Port Automatic Network Analyzer

(DSPANA) over the frequency range

10 MHz to 18 GHz.

In addition to measurements per- formed on the DSPANA, measure- ments at a fixed frequency of 30 MHz

are available referenced to the NIST

waveguide below cutoff standard at this frequency.

Coaxial attenuators are normally

measured in a system having a

characteristic impedance of 50 ohms.

Limits of uncertainty depend upon

the VSWR of the individual attenuator, quality of the attenuator and connectors, and the magnitude of the

attenuation. Typical systematic uncertainties range from 0.03 to 0.05 dB/10

dB of attenuation up to 60 dB.

Waveguide Circular Piston Attenuator Measurements at 30 MHz (61215C)

Incremental attenuation is the change

in attenuation of an adjustable attenuator between a reference set- ting (usually zero) and any other set- ting. The same restraints on system

conditions apply as for attenuation.

The term "differential attenuation" is sometimes applied to this case and

usually refers to two nonzero set- tings.

Measurements on waveguidebelow-cutoff (piston) attenuators are performed at 30 MHz. These attenuators are normally quite stable and sel- dom need recalibration unless damaged or mechanically worn.

Since any laboratory can perform in- dependent checks to determine continuing repeatability and linearity of

attenuation, we do not recommend

153
periodic NIST recalibrations. This

recommendation is also made because more damage can be suffered in transit than in daily use. In any measurement, the maximum power delivered

to the test attenuator will not exceed

400 mW. If the attenuator cannot tol- erate this power level, some reduction of measurement range will be

required.

Piston attenuators are normally cal- ibrated in a system having a characteristic impedance of 50 ohms. Since

only measurements of incremental at- tenuation are made on this type of at- tenuator. Type BNC, C, TNC, and

similar connectors are acceptable, but

precision connectors are preferred to reduce leakage. Limits of uncertainty

depend upon the quality of the atten- uator and connectors, as well as upon

the VSWR of the attenuator, and the

magnitude of attenuation. Typical

systematic uncertainties range from

0.003 to 0.005 dB/10 dB of attenuation. Total insertion loss must be less than 140 dB.

Special Attenuation Measurements

below 10 MHz (61220S)

Special tests may be performed over

the frequency range 30 kHz to 10 MHz using the voltage ratio measure- ment technique. These tests are limited to attenuators with GR 874

connectors and to 10 dB maximum.

Rectangular Waveguide Variable Attenuators (61230S)

Variable waveguide (usually rotary

vane) attenuators are calibrated by

the IF-substitution technique refer- enced to 30 MHz, direct rf substitution, or on the NIST DSPANA, as appropriate. Service is available for frequencies corresponding to waveguide sizes WR28, WR42, WR62,

WR90, WR137, and WR187.

Requested measurements should be

for a minimum number of settings at a single band-center frequency and be

sufficient to determine the characteristics of the device. Previously cali- brated units should not be resubmitted unless tests performed by the

user indicate a shift in values. The uncertainty is a function of resettability, internal leakage, and quality of flanges. Except for measure- ments made on the NIST Dual Six- Port Automatic Network Analyzer,

the uncertainty is also a function of

the VSWR of the waveguide ports.

Devices submitted should be in the

best possible condition to justify cali- bration and to ensure long-term sta- bility of measured values. Typical

systematic uncertainties range from

0.03 to 0.05 dB/10 dB of attenuation

up to 50 dB.

Special Attenuation Measurements at 1.25 MHz (61240S)

A provisional service is now avail- able for attenuation measurements of

special three-port devices at 1.25 MHz. A measurement system has

been developed to measure the

change in the ratio S21/S31 of special

stable two-position three-port

devices, sometimes called voltage

doublers, at 1.25 MHz. The device

must have an input for a 1.25-MHz

source (port 1), a reference output

(port 3), and an output (port 2) with

a level switchable to two different values. The two levels of the bi-level output have a nominal ratio of

6.0206 dB.

If Pri is the reference power level when the bi-level output is at level 1 (Pbi), and Pr2 is the reference power

level when the bi-level output is at level 2 (Ph:), then parameter measured is given by the following equation:

10 Log,o (^)- 10 Log.o (^) dB

154
61210S-61250S

where the subscripts (1) and (2) refer

to the switch positions 1 and 2, re- spectively. The above is equivalent to

10 log,

S:.(l)/S,i(l)

S„(2)/S„(2)

The loads presented to the two

outputs are 50 ohms. The device

must allow the signal input to be of

such strength that the bi-level output

is at least 10 mW in the high-level

position.

The total uncertainty of the measurement system in measuring a 6-dB

change in attenuation is estimated to have a systematic error no greater

than 5 jaB and a random error of

about 3 JU.B, where 1 jaB=10 ' dB or about 2.3 ppm of the power ratio. Two-port step attenuators having a nominal change in attenuation of

6 dB can also be measured by this system at 1.25 MHz.

References—Attenuators, RF and

Microwave

1.25 MHz Attenuation Measurement

System, R. A. Ginley and C. M.

Allred, IEEE Trans, on Instru- mentation and Measurement,

IM-35, No. 4, Pt. 1 (Dec. 1986).

Effects of Connectors and Adapters on Accurate Attenuation Measurements at Microwave Frequencies,

R. W. Beatty, IEEE Trans. In- strum., IM-13, 272 (Dec. 1984).

"Thru-Reflect-Line": An Improved

Technique for Calibrating the Dual

Six-Port Automatic Network Analyzer, G. F. Engen and C. A.

Hoer, IEEE Trans. Micr. Theory

Tech., MTT-27, 987 (Dec. 1979).

A Network Analyzer Incorporating

Two Six-Port Reflectometers,

C. A. Hoer, IEEE Trans. Micr.

Theory Tech., MTT-25, 1070

(Dec. 1977).

The Six-Port Reflectometer: An Alternative Network Analyzer, G. F. Engen, IEEE Trans. Micr. Theory

Tech., MTT-25, 1075 (Dec. 1977).

Insertion Loss Concepts, R. W.

Beatty, Proc. IEEE 55, 6, 663

(June 1964).

RF Attenuation, D. Russell, Proc. IEEE 55, 6, 942 (June 1967).

Application of Waveguide and Circuit Theory to the Development of

Accurate Microwave Measurement

Methods and Standards, R. W.

Beatty, Natl. Bur. Stand. (U.S.),

Monogr. 137 (Aug. 1973).

Specifications and Test Methods for Fixed and Variable Attenuators, dc

to 40 GHz, IEEE Standard 474

(1973).

Basic Theory of Waveguide Junctions and Introductory Microwave

Network Analysis, D. M. Kearns

and R. W. Beatty, Intl. Ser. of

Monogr. in Electromag. Waves, 13, 59, Pergammon Press, New York,

NY (1967).

I

155
61310S-61330S

G. Microwave Measurements

G.3 Coaxial and Waveguide Terminations,

Reflection Coefficients

Technical Contacts:

John R. Juroshek

Tel: 303/497-5362

Keith C. Roe

Tel: 303/497-3365 Kathy Hillen Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 61310S Complex Reflection Coefficient, Impedance, and

Voltage Standing Wave Ratio of Coaxial

Terminations, Frequency Range 10 MHz to 18 GHz

61320S Magnitude of Reflection Coefficient of Rectangular

Waveguide Reflectors (Mismatches) with Standard

Flange Connectors, Specify Frequency for Waveguide Sizes WR28, WR42, WR62, WR90,

WR112, WR137, and WR187, T: 0.025 to 0.2 6 132 IS Special Reflection Coefficient Measurements, by

Prearrangement

61330S Magnitude of Reflection Coefficient of Nonreflecting

Waveguide Ports and Matched Loads, Specify

Frequency for Waveguide Sizes WR28, WR42,

WR62, WR90, WR112, WR137, WR187, WR284,

T: 0.0001 to 0.025

Coaxial and Waveguide Terminations,

Reflection Coefficient (61310S-61330S)

Services provided in this category are

for passive devices over the fre- quency range from 10 MHz to 95

GHz. Available calibration frequencies are listed in the test descriptions.

Highest accuracy is obtained only for standards equipped with precision

coaxial connectors or waveguide

flanges. Standards submitted for cali- bration should be in good repair and.

except for very minor cleaning of

connector surfaces, should require no

recalibration maintenance. NIST does

not provide repair services. Items re- ceived requiring maintenance will be

returned to the sender, and a handling fee will be charged.

Coaxial Terminations (61310S)

Services are available for complex

impedance, reflection coefficient, and

voltage standing wave ratio (VSWR).

Measurements on coaxial devices in the frequency range 10 MHz to 18 GHz are made on the NIST Dual

Six-Port Automatic Network Analyzer (DSPANA). The calibration

service usually determines the complex reflection coefficient of standard

terminations or mismatches. Typical

uncertainties are ±0.005 to 0.02 in re- flection coefficient.

Waveguide Terminations

(61320S-61330S)

Waveguide terminations are measured

in a reflectometer system relative to a quarter-guide wavelength short cir- cuit and a precision transmission line. Some measurements in waveguide

bands below 18 GHz can be per- formed on the NIST DSPANA; all of those above 18 GHz are per- formed on manual fixed-frequency

systems. (See test descriptions

above.) Typical uncertainties are ±0.001+0.0035 r. Waveguide terminations are usually

quite stable and need not be resubmitted unless tests performed by the user

indicate a shift in values. The terminations must be fitted with standard

waveguide flange connectors. The

faces of these flanges should be machined flat and smooth and should

not contain protrusions or indentations. Considerable care must be exer- cised in keeping the mating connector

flange surfaces smooth and clean. Accurate alignment of the interior sur- faces of the joining waveguides at the

flange junction also is very important.

The back of the flange which makes

contact with the connecting bolts should be nominally flat and free of

156
soft materials, including paint. The

connecting holes of the flange should

be symmetrically and accurately

aligned to the rectangular waveguide

opening. These precautions must be

observed when using a waveguide

termination in a precision measure- ment system.

Assigned limits of uncertainty depend upon the quality of the flanges

as well as the numerical value of re- flection coefficient magnitude. Systematic errors assigned by NIST vary

with waveguide size and depend on

the absolute dimensions of the precision transmission lines.

References—Coaxial and Waveguide

Terminations, Reflection Coefficients

"Thru-Reflect-Line": An Improved

Technique for Calibrating the Dual

Six-Port Automatic Network Analyzer, G. F. Engen and C. A.

Hoer, IEEE Trans. Micr. Theory

Tech., MTT-27, 987 (Dec. 1979).

A Network Analyzer Incorporating

Two Six-Port Reflectometers,

C. A. Hoer, IEEE Trans. Micr.

Tech., MTT-25, 1070 (Dec. 1977).

The Six-Port Reflectometer: An Alternative Network Analyzer, G. F. Engen, IEEE Trans. Micr. Theory

Tech., MTT-25, 1075 (Dec. 1977).

Millimeter Attenuation and Reflection Coefficient Measurement System, B. C. Yates and W. Larson,

Natl. Bur. Stand. (U.S.), Tech.

Note 619 (1972).

A Guide to the Use of the Modified

Reflectometer Technique of

VSWR Measurement, W. J. Anson,

J. Res. Natl. Bur. Stand. (U.S.),

65C, 4, 217 (Oct.-Dec. 1961). (The

measurement technique utilized in reflection measurements is described in this paper.)

1 57
61410S-61450S

#'^ Microwave Measurements

G.4 Phase Shifters, RF and Microwave

Technical Contacts:

John L. Workman John R. Juroshek Kathy Hillen

Tel: 303/497-3954 Tel: 303/497-5362 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 61410S Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference; Precision Connectors; Measured at 30 MHz, Range 0-360° 6141 IS Coaxial Fixed and Variable Phase Shifters; Characteristic Phase Shift Difference; Precision Connectors; Frequency Range 1-18 GHz, Phase

Range 0-360° 61420S Variable Rectangular Waveguide Phase Shifters; Phase Shift Difference; VSWR <1.4; Specify

Frequencies for Waveguide Sizes WR62, WR90,

Range 0-720°, All Phase Shifters, by Prearrangement

61450S Special Tests of Phase Shifters, by Prearrangement

Phase Shifters, RF and Microwave

(61410S-61450S)

The specific phase shift services listed below are available on a limited basis depending on other demands and

staff availability. Measurements not

listed may possibly be provided if suf- ficient advance notice is given. The

cost of such services must be negotiated and will, in general, be higher

than the established phase shift ser- vices. Consultation by telephone or

written correspondence is suggested.

Often a measurement technique can

be suggested that will permit the cus- tomer to perform calibrations in- house with appropriate reference to other NIST-supported standards.

Coaxial Phase Shifters (61410S and

61411S)

Fixed and variable coaxial two-ports

are measured on the NIST Dual Six- Port Automatic Network Analyzer

over the frequency range 10 MHz to

18 GHz. In addition, measurements

can be performed with reference to a precision variable air line at 30 MHz.

Because of the specialized nature of

coaxial phase shifting components,

prior discussions should be held with

NIST staff before submission of any

devices to NIST. Items to be cahbrated must be fitted with connectors

having a known plane of reference,

such as sexless precision connectors, or Type N connectors meeting Mil.

Std. C39012. The phase angle measured is ^ + 360n, where n is an

integer. The value of n is not deter- mined.

Limits of uncertainty are:

Frequency Range Uncertainty

30 MHz 0-360° 0.1-0.5° 0.1-18 GHz 0-360° 0.5°

These limits of uncertainty are the sums of systematic and random errors. The values are dependent upon

the particular standard under calibration. The VSWR of the device and

the quality of the connectors will contribute to the calibration uncertainties.

158
Edward Andrusko is shown at the system controller keyboard for one of NIST's

dual six-port automatic network analyzers covering the frequency range 0.5 to 18 GHz.

Phase Shifters (61420S)

For a rectangular waveguide, the

measurement services are limited to phase shift difference at frequencies

below 18 GHz. Measurements are made on continuously variable

waveguide phase shifters with the zero value of the scale as the normal

reference position. Since 360 mechanical degrees of rotation represent 720

electrical degrees, attention should be

given to the relationship between dial indication and actual mechanical position of the rotating vane assembly.

The uncertainty is approximately

the same as for coaxial devices.

References—Phase Shifters,

RF and Microwave

UHF and Microwave Phase Shift Measurements, D. A. Ellerbach, Proc. IEEE 55, 6, 960 (June 1967).

159
61520S

^ Microwave Measurements

G. 5 N-Port Scattering Measurements

Technical Contacts:

r

Ronald A. Ginley John R. Juroshek Kathy Hillen

Tel: 303/497-3634 Tel: 303/497-5362 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 61520S Linear, Reciprocal 2-Port Devices, 10 MHz to

18 GHz

Scattering Parameters of Linear

N-Port Devices—General

Information

The signal levels at the ports of a lin- ear network having N-ports is dependent on the impedances or loads

presented to each of the N-ports. For

example, the power at a load con- nected to a source of given level through an attenuator is not only dependent on the properties of the at- tenuator but on the generator and

load impedances as well. In this ex- ample, insertion loss, as defined by

the IEEE Dictionary of Electrical

and Electronics Terms, is the ratio of

the power in the load before insertion

of the attenuator to that after insertion. Insertion loss, as given in this general definition, is a very poor measure of the property of the atten- uator as it is generator and load dependent. To alleviate this problem,

the parameters of the N-port network

are measured when the ports are pre- sented with reflectionless terminations. With such terminations, the

network is said to be measured under

matched conditions.

A particularly useful description of

N-port networks at higher frequencies where reflections are of importance in systems is the scattering or S-parameter description. It is couched

in terms of the incident and reflected waves at each of the N-ports. The

S-parameters have magnitude and

phase and are defined as:

g emergent wave at port i incident wave at port j

for i. j = 1, 2 . . . N, where all ports

other than the input port j are terminated with nonreflecting (matched)

terminations. Thus, for a two-port at- tenuator, I S21

1 " is the insertion loss and the argument of S21 is the inser- tion phase shift from port 1 to port 2 under matched conditions. Sn and S2: are the respective reflection coeffi- cients at ports 1 and 2; again, under

matched conditions.

For a one-port, there is only a sin- gle S-parameter, Sn, where Sn is the

reflection coefficient, T. The S-parameter fully describes the

network (as a black box) since, given

the S-parameters, one can completely

determine the relative signal relation- ships at the ports for any set of terminations presented to the ports be they

matched or not.

Linear, Reciprocal 2-Port Devices

(61520S)

Presently, routine tests are provided

only for linear, reciprocal, one-port

and two-port networks and then only over the frequency range 10 MHz to

18 GHz. NIST plans to extend

greatly the coverage in the near fu- ture by providing all S-parameter

measurements at most frequencies

from 100 kHz to 100 GHz, and for

IS12I up to approximately 60 dB us- ing NIST Dual Six-Port Automatic

Network Analyzers.

160
References—Scattering Parameters of

Linear N-Port Devices

"Thru-Reflect-Line": An Improved

Technique for Calibrating the Dual

Six-Port Automatic Network Analyzer, G. F. Engen and C. A.

Hoer, IEEE Trans. Micr. Theory

Tech., MTT-27, 987 (Dec. 1979).

The Six-Port Reflectometer: An Alternative Network Analyzer, G. F. Engen, IEEE Trans. Micr. Theory

Tech., MTT-25, 1075 (Dec. 1977).

A Network Analyzer Incorporating

Two Six-Port Reflectometers,

C. A. Hoer, IEEE Trans. Micr.

Theory Tech., MTT-25, 1070

(Dec. 1977).

161
62020S-62140S

Noise Temperature Measurements

Technical Contacts:

Sunchana Perera William C. Kathy Hillen

Tel: 303/497-3546 Daywitt Administrative

Tel: 303/497-3720 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 62020S Special Noise Temperature Measurements

(Electromagnetic), by Prearrangement

62100S Noise Temperature of Coaxial Noise Source, Type N

Precision, APC 3.5, or 14-mm Connectors, at 30 MHz

or 60 MHz; VSWR <1.2, Temperature:

77 K-15,000 K, ENR <17 dB

62101S Each Additional 62100S Item Tested at Same

Frequency within the Same System

621 lOS Noise Temperature of Coaxial Noise Source, Type N

Precision, 14 mm, or APC 7 Connectors; Continuous Frequencies 2.0-12.0 GHz, Reflection

Coefficient <0.2, Temperature: 77 K-15,000 K,

ENR <17 dB

621 1 IS Each Additional 621 1 OS Item Tested at Same

Frequency within the Same System

621 15S Special Service for Waveguide Noise Sources in WR284, WR187, WR137, WR112, and WR90;

Continuous Frequencies within the Bands from

2.6 to 12.0 GHz; Reflection Coefficient <0.2,

Temperature: 77 K-15,000 K, ENR <17 dB

62116S Each Additional 621 15S Item Tested at the Same

Frequency within the Same System

Test No. Items 62120S Noise Temperature of Rectangular Waveguide Noise

Sources at Specific Frequencies in WR62 (12.4, 13.5,

14.0, 15.0, 16.0, 16.5, 17.0, 18.0 GHz) and WR90 (8.2, 9.0, 9.5, 9.8, 10.0, 10.5, 11.2, 11.8, 12.4 GHz);

Reflection Coefficient <0.09, Temperature:

9.000 K-17,000 K, ENR <17.6 dB

62 12 IS Each Additional 62120S Item Tested at Same

Frequency within the Same System

62130S Noise Temperature of WRIO Noise Sources,

Continuous Frequencies between 94.5 GHz and

96.6 GHz, Reflection Coefficient <0.2,

Temperature 77 K-15,000 K, ENR <17 dB

62 13 IS Each Additional 62 BOS Item Tested at the Same

Frequency

62132S Noise Temperature of WR15 Noise Sources,

Continuous Frequencies between 55.0 GHz and

64.5 GHz, Reflection Coefficient <0.09,

Temperature 300 K-15,000 K, ENR <17 dB

62133S Each Additional 62132S Item Tested at the Same

Frequency

62140S Special Services for Earth Terminals Used in Satellite Communications

162
Noise Temperature Measurements

Electromagnetic (62020S)

Special-test services for the measure- ment of electromagnetic thermal

noise are offered in limited frequency

coverage from 30 MHz to 96.5 GHz

and include measurements through

adaptors and out-of-range noise temperatures. Some gaps in the fre- quency coverage exist. In some

frequency regions, only spot fre- quency measurements are available. Depending on the frequency cover- age available, noise sources submitted

for measurement will be compared,

via one of three different types of ra- diometers, against a hot or cold primary reference standard or a transfer standard. Since there are limitations

which are a function of the noise

standards and radiometer available,

the customer should check with the

technical contact listed at the beginning of this section before submitting

a device for calibration.

Noise Sources (62100S-62133S)

Noise temperature measurements are

available on single-port, coaxial, and

rectangular waveguide noise sources under conditions of continuous, un- modulated operation. Precision coaxial connectors or clean, smooth, and

flat standard EIA waveguide flanges are required. Complete operating in- structions and special electronic connectors should be supplied, and

pertinent operating conditions

(voltages, circuits, etc.) specified for the noise source to be measured.

Devices submitted that are not of sufficient quality or not mechanically

compatible with the measuring sys- tem will be rejected and an appropriate fee charged. Availability of

measurements at specific frequencies

and for various connector types are

specified above. Generally, an at- tempt is being made to expand ser- vices to include more types of

precision connectors and waveguide

sizes. However, the cost of measure- ments requiring the use of adaptors as part of the measurement process can

be substantially greater than the cost of measurements on sources with

connectors mating directly to the

measurement system. Furthermore,

measurement results on devices sub- mitted with adaptors attached may

apply only to the source/adaptor

combination.

The limits of uncertainty vary with

noise temperature, reflection coefficient, and source and connector stability, but typically lie between 1 percent and 3 percent of the noise

temperature.

Earth Terminals for Satellite Communications (62140S)

Measurement and consultation ser- vices are available on a limited and

special basis for characterizing the

noise properties of earth terminals.

Quantities such as G/T (gain to sys- tem noise temperature ratio) and sys- tem noise temperature are also

available. Special arrangements need

to be made for these services.

1 63
References—Noise Temperature

Measurements

A Derivation for the Noise Temperature of Horn-Type Noise Standards, W. C. Daywitt, Metrologia

21, 127 (Sept. 1985).

A Coaxial Noise Standard for the

1-GHz to 12.4-GHz Frequency

Range, W. C. Daywitt, Natl. Bur.

Stand. (U.S.), Tech. Note 1074

(Mar. 1984).

The NBS WR62 and WR90 Refer- ence Noise Standards, C. K. S. Miller and W. C. Daywitt, Natl. Bur. Stand. (U.S.), NBSIR 84-3005

(May 1984).

The NBS Switching Radiometers,

C. K. S. Miller and W. C. Daywitt,

Natl. Bur. Stand. (U.S.), NBSIR

84-3004 (May 1984).

Design and Error Analysis for the

WRIO Thermal Noise Standard,

W. C. Daywitt, Natl. Bur. Stand.

(U.S.), Tech. Note 1071 (Dec.

1983).

Precision Measurement of Antenna

System Noise Using Radio Stars, D. F. Wait, IEEE Trans. Instrum. Meas., IM-32, 1 (Mar. 1983).

WR15 Thermal Noise Standard,

W. C. Daywitt, W. J. Foote, and

E. Campbell, Natl. Bur. Stand.

(U.S.), Tech. Note 615 (Mar. 1972).

1 64
J Electromagnetic Field Strength and Antenna

M Measurements

/. / Microwave Antenna Parameter

Measurements

Technical Contacts:

Allen C. Newell Katie MacReynolds Andrew G. Repjar Kathy Hillen 63100S-63400S 63100S 63200S Administrative

Tel: 303/497-3743 Tel: 303/497-3471 Tel: 303/497-5703 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Shipping Address: Room 1300, Bldg. 24, National Institute of Standards and Technology, 325 Broadway, Boulder,

CO 80303-3328

Test No. Items 63100S Gain and Polarization Calibrations of Standard Antennas Using Extrapolation Range

63200S Measurement of Pattern, Gain, and Polarization of

Arbitrary Antennas Using Near-Field Scanning

Techniques

63300S Special-Test Service for Calibration of Probes Used

with Near-Field Scanning Facilities 63400S Special Consulting, Advisory, and Other Services

Antenna Parameter

Measurements (Microwave)

General Information

Accurate measurements of antenna

gain, pattern, and polarization are generally available from about 750

MHz to about 65 GHz. However, be- cause the measurement accuracy, capability, and cost depend on the

frequency, type, and size of antenna,

and the parameters to be measured, a particular measurement service must

be negotiated in advance. Antennas

submitted for evaluation should be

mechanically and electrically stable in order to retain a calibration for a sig- nificant length of time. Antennas with

either coaxial or waveguide connectors can be measured; however, if coaxial connectors are employed,

they should be precision connectors

to minimize uncertainties due to a lack of connector repeatability. In

particular, the use of SMA connectors is strongly discouraged because

of poor connector repeatability. The

following methods and facilities are used for these measurements.

Gain and Polarization Calibrations

of Standard Antennas Using

Extrapolation Range (63100S)

This calibration service is offered primarily for determining the absolute

on-axis gain and polarization of stan- dard gain horns, which, in turn, are used as reference standards in deter- mining the gain and polarization of

other antennas by the gain comparison technique. In the extrapolation

method three antennas are normally

utilized, and three pairwise combinations are defined. The received signal

transmitted between each pair of an- tennas is measured as a function of

the separation distance between the antennas. The antennas need not be

identical, and no assumptions con- cerning the polarization are required.

The method is not well suited for pattern measurements but is the most

accurate technique known for absolute gain and polarization measurements. Above 1 GHz, the accuracies

are typically ±0.10 dB for gain measurements and ±0.05 dB/dB for polarization axial measurements. There

are antenna size limitations associated

with existing NIST extrapolation

ranges. These limitations depend on

the type of antenna, the frequency,

and the desired measurements and ac- curacies. Therefore, negotiations must

be conducted prior to submitting an- tennas for calibration to ascertain

whether all requirements can be met.

165
Measurement of Pattern, Gain, and

Polarization of Arbitrary Antennas

Using Near-Field Scanning Techniques

(63200S)

With this technique, gain, pattern,

and polarization parameters are cal- culated from near-field amplitude and

phase measurements taken over a sur- face close to the test antenna. The ab- solute gain can be determined to within about 0.15 dB, the polarization

axial ratio to within about 0.10 dB/

dB, and side lobe levels can be obtained down to —50 or —60 dB. The

exact uncertainties in these parameters will depend on such factors as the frequency, type, and size of antenna. Antennas with apertures up to about 3.5 meters in diameter can be

managed. Measurements can be made

from about 750 MHz to about 65

GHz. Measurements are most com- monly made over a plane surface in front of the antenna being evaluated,

but the capability also exists for measuring over a cylindrical surface sur- rounding the antenna when it is advantageous to do so. Calibrated

probes are normally required for these measurements. These near-field

scanning measurements are offered as a special-test service because nearly

every measurement is unique and it is difficult to build up a statistical his- tory as required for a regular calibra- tion service.

Special-Test Service for Calibrating

Probes Used with Near-Field Scanning

Facilities (63300S)

This special-test service is available

to support those organizations that have established their own near-field

measurement facilities and need to characterize the probes used in per- forming the near-field measurements.

In order to achieve accurate results with either the planar, cylindrical, or

spherical near-field method, the trans- mitting or receiving properties of the

probe must be known. With this in- formation, the measured data can be

corrected for the nonideal pattern

and polarization properties of the

probe. Probes are characterized by a three-step process: (1) The on-axis

gain and polarization properties are measured using the extrapolation

technique described above; (2) the

far-field amplitude and phase patterns

are measured for two nominally or- thogonal polarizations of the incident

field; and (3) the on-axis and pattern

data are combined to obtain the

probe correction coefficients at the

desired lattice points on the measure- ment surface as specified by the cus- tomer. The final output consists of a computer tape containing the measured far-field patterns and the calculated probe coefficients. Typical

types of probes are open-ended

waveguides and small horns. Both

linearly and circularly polarized

probes can be evaluated.

Douglas Kremer adjusts a large phased-array antenna

before measuring its characteristics on the NIST an- tenna near-field planar scanning range at Boulder, CO.

166
Special Consulting, Advisory, and

Other Services (63400S)

A variety of special consultation and

advisory services related to the measurements described above are avail- able upon request. These services are offered to disseminate NIST tech- nologies and to assist other organizations in establishing their own

measurement facilities and capabilities. Included are cooperative measurement programs. A customer

actually participates directly in the

measurement of his device in order to become familiar with the measure- ment methods and assist in the analysis of the results. This is a useful approach when one is attempting to

establish a new measurement capability that is related to or based upon

NIST measurement techniques.

References—Microwave Antenna

Parameter Measurements

Accurate Determination of Planar

Near-Field Correction Parameters

for Linearly Polarized Probes,

A. G. Repjar, A. C. Newell, and

M. H. Francis, IEEE Trans. Antennas Propagat., Vol. 36, No. 6

(June 1988).

Improved Polarization Measurements

Using a Modified Three-Antenna

Technique, A. C. Newell, IEEE

Trans. Antennas Propagat., Vol.

36, No. 6 (June 1988).

Gain and Power Parameter Measurements Using Planar Near-Field

Techniques, A. C. Newell, Robert

Ward, and Edward McFarlane,

Hughes Aircraft Company, IEEE

Trans. Antennas Propagat., Vol.

36, No. 6 (June 1988).

Error Analysis Techniques for Planar

Near-Field Measurements, A. C. Newell, IEEE Trans. Antennas

Propagat., Vol. 36, No. 6 (June

1988).

Effect of Random Errors in Planar

Near-Field Measurement, A. C. Newell and C. F. Stubenrauch,

IEEE Trans. Antennas Propagat.,

Vol. 36, No. 6 (June 1988).

An Efficient and Accurate Method

for Calculating and Representing

Power Density in the Near Zone

of Microwave Antennas, R. L. Lewis and A. C. Newell, IEEE

Trans. Antennas Propagat., Vol.

36, No. 6 (June 1988).

Plane-Wave Scattering-Matrix Theory of Antennas and AntennaAntenna Interactions, D. M. Kerns,

Natl. Bur. Stand. (U.S.), Monograph 162 (June 1981).

Plane-Wave Scattering-Matrix Theory of Antennas and AntennaAntenna Interactions: Formulation

and Applications, D. M. Kerns, J. Res. Natl. Bur. Stand. (U.S.), 80B,

I, 5051 (Jan.-Mar. 1976).

Upper-Bound Errors in Far-Field

Antenna Parameters Determined

from Planar Near-Field Measurements, A. D. Yaghjian, Natl. Bur.

Stand. (U.S.), Tech. Note 667 (Oct.

1975).

Accurate Measurement of Antenna

Gain and Polarization at Reduced

Distances by an Extrapolation

Technique, A. C. Newell, R. C.

Baird, and P. F. Wacker, IEEE

Trans. Antennas Propagat., AP-21,

4, 418 (July 1973).

Determination of Both Polarization

and Power Gain of Antennas by a Generalized 3-Antenna Measurement Method, A. C. Newell and

D. M. Kerns, Electronics Letters,

7, 7, 68 (Feb. 1971).

Correction of Near-Field Antenna

Measurements Made with an Arbitrary but Known Measuring Antenna, D. M. Kerns, Electronics

Letters, 6, 11, 346 (May 1970).

New Method of Gain Measurement

Using Two Identical Antennas,

D. M. Kerns, Electronics Letters 6, II, 348 (May 1970).

167
64100S-64400S

/Electromagnetic Field Strength and Antenna

i Measurements

1.2 Field Strength Parameter Measurements

Technical Contacts:

Galen H. Koepke Ezra B. Larsen Motohisa Kanda Kathy Hillen

Tel: 303/497-5766 Tel: 303/497-3540 Tel: 303/497-5320 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.03, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 64100S Special-Test Service for Antennas/Field Strength

Measurements, Utilizing the Transverse Electromagnetic (TEM) Cell Method (10 kHz-300 MHz)

64200S Special-Test Service for Antennas/Field Strength

Measurements, Utilizing the Open-Field Method

64300S Special-Test Service for Antennas/Field Strength/

Reflectivity Measurements, Utilizing the Anechoic-Chamber Method

64400S Special-Test Service for Electromagnetic

Interference

Special-Test Service for Antennas/

Field Strength Measurements,

Utilizing the Transverse

Electromagnetic (TEM) Cell Method

(64100S)

Standard electromagnetic fields are generated in TEM cells and used to calibrate electrically small antennas and antenna systems used for electro- magnetic field probes in the fre- quency range 10 kHz to 300 MHz.

Special-Test Service for Antennas/

Field Strength Measurements,

Utilizing the Open-Field Method

(64200S)

These measurements include calibra- tion of antenna factor and gain of an- tennas used in conjunction with field strength meters, and of electrically

small antennas used in electromagnetic field probes. The following

methods and facilities are used for these measurements:

A. Dipoles, log-periodic, and

other antennas (25 to 1000 MHz) are used to generate electromagnetic

fields which are used for calibrating

various antennas and electromagnetic

field probes. The field strength is es- tablished using the standard receiving

antenna method.

B. Monopoles (30 kHz to 300

MHz) are used to generate standard

electric fields for calibrating antennas and electromagnetic field probes. C. Loop antennas (14 kHz to 50

MHz) are used to generate standard

magnetic fields for calibrating loop

antennas used in conjunction with

field strength meters.

Special-Test Service for Antennas/

Field Strength/Reflectivity

Measurements, Utilizing the Anechoic-Chamber Method (64300S)

A. Open-end waveguides (200 to 450 MHz) are used to generate stan- dard electromagnetic fields for cali- brating antennas and electromagnetic

field probes.

B. Pyramidal horns (0.45 to 18 GHz) are used to generate standard

electromagnetic fields for calibrating antennas and electromagnetic field probes, and for measuring reflectivity

of materials.

Table 21 summarizes the field parameters, frequency ranges, and ra- diating antenna sources for the vari- ous NIST field strength measurement

facilities.

168
Table 21: Summary of NIST Standard

Field Strength Facilities

Type of Radiating

rlciO ivicaburcnicnc Frequency Antenna

ParaiTiPtpr Fflcility H Wood 14 kHz to Loop (20 cm)

building dU MMz

E (vertical) Open site 30 kHz to Short

(ground screen) iU Mhlz monopole

E (vertical) Open site 30 to Quarter wave

(ground screen) 300 MHz length

monopole

E (horizontal) Open site 25 to Dipole, log- 1000 MHz periodic antenna, etc. Power Density Anechoic 200 to Open-end

chamber 450 MHz waveguide

Power Density Anechoic 0.45 to Pyramidal

chamber 18 GHz horn

Material Anechoic 0.45 to Pyramidal

Reflectivity chamber 18 GHz horn

Special-Test Service for Electromagnetic Interference (64400S)

This service includes evaluating

equipment used for measuring the electromagnetic environment, per- forming radiated-field susceptibility

(immunity) and emission testing, and

performing conducted interference

testing. In special cases, measure- ments will be made to evaluate facili- ties used to perform electromagnetic

interference tests (susceptibility, emission, or conducted) and to evaluate

localized electromagnetic environments.

References—Electromagnetic Field

Strength Parameter Measurements

Methodology for Standard Electromagnetic Field Measurements,

N. S. Nahman, M. Kanda, E. B. Larsen, and M. L. Crawford,

IEEE Trans. Instrum. Meas.,

IM-34, 4 (Dec. 1985).

A Review of Electromagnetic Compatibility/Interference Measurement Methodologies, M. T. Ma,

M. Kanda, M. L. Crawford, and

E. B. Larsen, Proc. IEEE, 73, 3, 388 (Mar. 1985).

169
65100S-65400S

J.

Pulse Waveform Measurements

Technical Contacts:

William L. Gans

Tel: 303/497-3538 David WaitTel: 303/497-3610 Kathy Hillen Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 723.10, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Test No. Items 65100S

65200S

65300S

65301S

65400S

Impulse Generator Spectrum Amplitude (50 Ohm)

Fast Repetitive Broadband Pulse Parameters

(50 Ohm)

Network Impulse Response (Frequency Domain

Parameter S21) of Coaxial Networks, 10 MHz to

10.0 GHz, 0 to ±40 dB

Additional 65300S Item Tested at Same Time as First Pulse Time Delay through Coaxial Transmission

Lines

Pulse Waveform Measurements

General Information

NIST offers special-test services for a number of baseband pulse parameters.

These are broken down into four cat- egories: impulse generator spectrum

amplitude, fast repetitive baseband

pulse parameters, network impulse re- sponse, and pulse time delay. All of

these special-test services are per- formed on the NIST Automatic Pulse

Measurement System (APMS), which

consists of a sampling oscilloscope in- terfaced to a minicomputer. In addition, all of these special tests are performed at cost. References pertaining to these four services are lo- cated at the end of this section.

Impulse Generator Spectrum

Amplitude, 50 Ohms (65100S)

In response to calibration needs from

the electromagnetic interference

(EMI) community, NIST has developed a special-test service to calibrate

the broadband spectrum amplitude

output from impulse generators. Such

a generator can then be used as a

transfer standard of broadband impulsive noise for field calibration of

spectrum analyzers and field intensity

Electrical Pulse Inputs

t \

Operator Minicomputer

System -Output

Waveforms

Correl, Funct. Complex Spectra

t \

Optical Pulse Inputs

meters. The NIST special-test service uses the time-domain measurement/

frequency-domain deconvolution

computational method for calibration

of impulse generators. A wideband

(dc-18 GHz) sampling oscilloscope is used to measure the time-domain

waveform from the impulse generator. A dedicated minicomputer then

computes the spectrum amplitude,

S(f), versus frequency using the fast Fourier transform (FFT). NIST will provide 50 to 200 data points over a wide frequency range for a single fee. NIST impulse generator spectrum

amplitude measurement service capabilities are shown in Table 22.

170
65100S-65400S

Table 22: NIST Impulse Generator Spectrum Amplitude

Measurement Service Capabilities

Parameter Limits Notes

Maximum impulse

dill amnlitiiHp L/l 1 1 UU\^ witViOiit W 1 11 lv7 U I attenuators ±600 mV 1, 2, 3 Maximum impulse

amplitude with

external attenuators ±1.2 kV 3,4

Spectrum amplitude — 15 dBjLiV/MHz<[S(0 _ So] < + 5 dBju,V/MHz5, 6, 7

S(f) uncertainty Nominally f< 1 GHz,

+0.6 dB

lGHz<f<4GHz,

±1.2 dB

4 GHz<f< 10 GHz,

±2.0 dB

5,

6,7

8& 9 Frequency range 5 MHz to 10 GHz 5,6,7,&10

Frequency spacing Af=5, 10, 20, 50, or

100 MHz 5, 10 Frequency uncertainty of the order of ±1% 7 Load impedance 50.0 fl Load impedance

uncertainty

Nominally ±0.1 O at dc

VSWR < 1.3 up to 10 GHz

8, 11

Trigger pulse

amplitude > 100 mV 12

Trigger pulse

transition duration <5 ns 12 Trigger to impulse

delay 75 ns<ti< 100 ns 12 Trigger to impulse

jitter <20 ps 12

Notes: 1. The impulse generator is characterized by its impulse output waveform into 50 ohms of peak amplitude (VpO- 50 percent level duration (t), and low-frequency spectrum amplitude (Sn=:2VpkT).

2. Impulse generator with an adjustable amplitude impulse out- put will be calibrated with the generator adjusted to give a peak ampli- tude in the range of 200 to 400 mV.

3. Impulse generators with fixed outputs greater than ±400 mV

must have the impulse attenuated to the 200-400 mV level by 50-ohm

wideband coaxial attenuators.

4. Either customer-supplied or NIST attenuators may be used.

5. Depends upon actual generator characteristics.

6. Data will not be given in the first spectrum null or at fre- quencies above. Typically 100 data points are supplied.

7. Subject to revision.

8. Only for impulse amplitudes less than ±400 mV.

9. If external attenuators and/or a 6-dB tee and delay line are

used, then the uncertainty associated with the attenuator calibration is added to these values.

10. Lower frequencies (<5 MHz) are available as a special test.

11. Depends upon input impedance of external attenuators when

used.

1 2. If the impulse generator does not supply a trigger output or if the trigger output does not have the proper characteristics, then a 6-dB

tee and a delay line will be used to provide a suitable trigger pulse.

Fast Repetitive Baseband Pulse

Parameters, 50 Ohms (65200S)

NIST offers a special-test service for selected pulse parameters. These

parameters are measured with the

NIST Automatic Pulse Measurement

System (APMS), which consists of a calibrated wideband (nominally dc-18

GHz) equivalent-time sampling oscil- loscope custom interfaced to a dedicated minicomputer system. The

parameters, ranges, and estimated uncertainty limits for this service are

listed in Table 23.

Table 23: Limits of Uncertainty for Calibration of Fast

Repetitive Baseband Pulse Parameters

Typical Limits of Parameter Range Uncertainty*

Pulse Baseline (0% level) + 500 mV ±(0.5% + 3 mV)

Pulse Topline (100% level) + 500 mV ±(0.5% + 3 mV)

Pulse Amplitude ± 500 mV ±(0.5% + 3 mV)

Pulse Overshoot/ ± 500 mV ±(0.5%, + 3 mV)

Undershoot

Pulse First Transition Duration (Rise Time) 10 ps--100 ns ±(0.5% + 3 ps) Pulse Second Transition Duration (Fall Time) 10 ps--100 ns ±(0.5% + 3 ps) Pulse Duration (between

50% levels) 10 ps--100 ns ±(0.5% + 3 ps)

* Smaller limits of uncertainty are achievable in some cases.

171
Restrictions: 1. Customer's device

must generate a repetitive pulse with

repetition rate between 100 Hz and 1 GHz.

2. Customer's device

must have a 50-ohms nominal output

impedance.

3. Customer's device

should have a precision coaxial out- put connector, e.g., SMA, APC-7,

Type "N," APC-3.5, etc.

4. Pulse topline is only

measured for "step-like" pulses.

5. Pulse second transi- tion duration and pulse duration are only measured for "impulse-like"

pulses.

6. Pulse overshoot/

undershoot is estimated as a percent

of pulse amplitude.

This measurement service includes

the previously offered measurement

service referred to in prior editions of

the SP250 Appendix as "Low-Pass

Filter Transition Duration."

Measurements of other pulse

parameters or parameter ranges may

be provided by special arrangement.

Consulting and advisory services also are available.

Network Impulse Response (65300S)

A network time-domain impulse re- sponse measurement service for coaxial networks is offered at NIST. The

resulting data are in the form of a dis- crete waveform vector, normally

1024 points in length, with a time

window range of from 2 ns to 100 ns. Also, using discrete Fourier trans- forms, the associated frequencydomain data (S2i[f]) are provided over a frequency range of 10 MHz to 10 GHz and a gain or loss range of 0

to 40 dB.

These measurements are accomplished by use of the NIST Automatic Pulse Measurement System,

which consists of a fast transition duration pulse generator, a 20-ps, 50- ohm sampling oscilloscope and a minicomputer. Two waveforms are measured, one with the pulse generator connected directly to the oscilloscope, and the other with the un- known network inserted between the

generator and the oscilloscope. The

time-domain impulse response function and/or the frequency domain

scattering parameter, S2i(f). are then

calculated using an NIST-developed

deconvolution algorithm. A wide variety of connectors can be accommodated. The approximate limits of

uncertainty are less than ±2 percent

for all parameters.

This measurement service includes

the previously offered measurement

service referred to in prior editions of

SP250 as "Wideband Attenuation or Gain of Coaxial Networks."

Pulse Time Delay through Coaxial

Transmission Lines (65400S)

NIST offers a special-test service for pulse time delay using the same

measurement system described in item 65300S above. The pulse time

delay is measured in the range of 100

ps-100 ns with typical limits of uncertainty of ±(1% + 10 ps). Smaller limits of uncertainty are achievable in some cases.

Restrictions: 1. Customer's device

must utilize precision coaxial connectors for both delay ports.

2. Customer should

provide driving pulse generator if possible. First transition duration (rise

time) of driving pulse generator

should not exceed 10 percent of pulse

time delay to be measured.

3. Customer's device

should have nominal input and output

impedances of 50 ohms.

Measurements for other ranges and

configurations may be made by special arrangement. Consulting and advisory services are available.

172
References—Pulse Waveform

Measurements

Calibration and Error Analysis of a Picosecond Pulse Waveform Measurement System at NBS, W. L. Gans, Proc. of the IEEE, Vol. 74,

No. 1, 86 (Jan. 1986).

The Measurement and Deconvolution

of Time Jitter in Equivalent-Time

Waveform Samplers, W. L. Gans,

IEEE Trans. Instrum. Meas.,

IM-32, 1, 126 (March 1983).

Deconvolution of Time Domain

Waveforms in the Presence of

Noise, N. S. Nahman and M. E. Guillaume, Natl. Bur. Stand.

(U.S.), Tech. Note 1047 (Oct.

1981).

Modeling of the Feed-through Wideband (dc to 12.4 GHz) Sampling

Head, S. M. Riad and N. S. Nahman, Digest, 1978 lEEEMTT-S Intl. Microwave Symp.,

Ottawa, Canada (June 1978).

Spectrum Amplitude Definition, Generation, and Measurement, J. R. Andrews and M. G. Arthur, Natl. Bur. Stand. (U.S.), Tech. Note 699

(Oct. 1977).

IEEE Standard Pulse Terms and

Definitions, IEEE Std. 194-1977;

and IEEE Standard on Pulse Measurement and Analysis by Objective Techniques, IEEE Std. 181-1977, Inst. Electrical and Electronic Engrs., New York, NY

(July 1977).

Impulse Generator Spectrum Amplitude Measurement Techniques,

J. R. Andrews, IEEE Trans. In- strum. Meas., IM-25, 4, 280 (Dec.

1976). Present Capabilities of the NBS Automatic Pulse Measurement System, W. L. Gans, IEEE Trans.

Instrum. Meas., IM-25, 384 (Dec.

1976).

Time Domain Automatic Network

Analyzer for Measurement of RF

and Microwave Components,

W. L. Gans and J. R. Andrews,

Natl. Bur. Stand. (U.S.), Tech.

Note 672 (Sept. 1975).

Pulsed Wavemeter Timing Reference

for Sampling Oscilloscope Calibration, J. R. Andrews and W. L. Gans, IEEE Trans. Instrum. Meas., IM-24, 82 (Mar. 1975).

Pulse Techniques and Apparatus,

Part 1: Pulse Terms and Definitions; Part 2: Pulse Measurements

and Analysis, General Considerations, lEC Publications 469-1 and

469-2, Intl. Electrotech. Com.

(lEC), Geneva, Switzerland

(1974).

1 73
Chapter

A Time and Frequency Dissemination

B Oscillator Characterization
Time and Frequency Measurements 761(XJS-76110S

Time and Frequency Dissemination

Technical Contacts:

George Kamas David W. Allan Kathy Hillen (Frequency) (Time) Administrative

Tel: 303/497-3378 Tel: 303/497-5637 and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 576.00, National Bureau of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Shipping Address: M.C. 576.06, Room 4039, National

Institute of Standards and Technology, 325 Broadway,

Boulder, CO 80303-3328

Test No. Items 76100S Special Tests of Time and Frequency; Frequency

Measurement Service (Frequency delivered to user's

site) 76 11 OS Special Tests of Time and Frequency; Global Time

Service (Frequency and Time delivered to user's site)

NIST Broadcast of Time and

Frequency Signals (No Test No.)

NIST offers several continuous time

and frequency dissemination services

that are freely available to the general public. These services are pro- vided via the radio broadcasts of

stations WWV, WWVH, and

WWVB, and a time-code disseminated from the GOES satellites. WWV's signal is also available by

dialing (303) 499-7111. A similar ser- vice from WWVH is available by

dialing (808) 335-4363. (These numbers are not toll free.) Broadcasts from WWV (Fort

Collins, Colorado) and WWVH

(Kauai, Hawaii) can be received on

conventional shortwave receivers

nearly anywhere in the world. Broadcast frequencies are 2.5, 5, 10, and 15 MHz for both stations and 20 MHz

for WWV only. Accuracies of 1 to 10 milliseconds in time and 1x10

in frequency are typical from these

broadcasts. These stations provide

standard frequencies, standard time

intervals, time-of-day announcements,

a binary-coded-decimal (BCD) time

code, astronomical time corrections,

and certain public service announce- ments for other government agencies.

For individuals without receivers, the

telephone service provides the same NIST time and frequency signals.

The time signal by telephone is accurate to only 30 milliseconds or better due to unpredictable delays in cross- country telephone line routings.

WWVB (Fort Collins, Colorado)

offers accuracies of 0.5 millisecond in time and 1 X 10^" in frequency but

requires a special 60-KHz lowfrequency receiver. WWVB's timecode signal is a BCD type needing

special decoding equipment. The

GOES satellites broadcast an NIST

time code accurate to 100 microseconds to the western hemisphere.

These are geostationary weather

satellites located at nominally 75° west and 135° west longitude.

NIST broadcast services are coordinated with similar operations in other countries. Commercial receivers designed to receive (and decode)

NIST broadcasts are available from

several manufacturers. A number of

publications are available to assist users to record properly the time and

frequency information available from

these broadcast services.

175
Special Frequency Measurement

Service (76100S)

Frequency calibration requirements at the part in 10" to a part in 10'" level can be satisfied using low-frequency

radio signals from broadcast stations such as WWVB or Loran-C. This

service involves a low-frequency re- ceiver and data logger system at the

user's site. The typical system contains a receiver, microcomputer, disc

units, and printer-plotter. A dedicated

phone line and modem must be pro- vided by the user so that his data can

be compared with that obtained at NIST, thus providing measurement

assurance. The user will also receive

a bulletin, either by telephone transfer or by mail, which reports the per- formance of many of the accurate

signal sources accessible by the sys- tem. To assist the user in getting the

maximum benefit from the service,

NIST provides specific training on

the actual equipment.

Special Global Time Service (761 lOS)

This service uses the Global Positioning System (GPS) satellites and an NIST-designed receiver, which provides much higher precision time and

frequency data and a high degree of

automation. The data from a receiver,

which is located at the user's facility, are automatically sent to an NIST

computer. The NIST computer then

stores the raw data, determines which

data are suitable for time transfer cal- culations, and provides an optimally

filtered value for the time and fre- quency of the user's clock with re- spect to the NIST atomic time scale. The results are communicated to the

user in a monthly report. The user is also given an account on one of the

NIST computers through which he

may access a preliminary NIST analysis, which is calculated daily. Tests between receivers in California, Colorado, Washington, D.C., France,

Germany, Spain, and Canada have

demonstrated an ability to perform

time comparisons with a precision of

1 X 10" or better (Icr) for averaging

times of 4 days and longer. While

useful characterization of frequency

stability is available to at least this latter level, frequency accuracy is limited to 8x 10"'^ the accuracy of

the NIST primary frequency stan- dard.

References—Time and Frequency

Dissemination

Accuracy of International Time and

Frequency via Global Positioning

System Satellites in Common

View, D. W. Allan et al., IEEE

Trans. Instrum. and Meas., IM-34,

2, 118 (June 1985).

New Time and Frequency Services at the National Bureau of Standards,

S. R. Stein, G. Kamas, and D. W.

Allan, Proc. 15th Annual Precise

Time and Time Interval (PTTI)

Applications and Planning Meeting, 17 (Dec. 1983).

NBS Time and Frequency Dissemination Services, Natl. Bur. Stand.

(U.S.), Spec. Publ. 432 (Sept.

1979).

176
Oscillator Characterization

Technical Contacts:

James E. Gray Kathy Hillen

Tel: 303/497-3209 Administrative and Logistics

Tel: 303/497-3753

Mailing Address: M.C. 576.06, National Institute of

Standards and Technology, 325 Broadway, Boulder, CO

80303-3328

Shipping Address: M.C. 576.06, Room 2019, National

Institute of Standards and Technology, 325 Broadway,

Boulder, CO 80303-3328

Test No. Items 77100C Precision Oscillator Frequency Calibration 771 IOC Characterization of Atomic Time and Frequency

Standards

77120C Characterization of Precision Oscillators: Time Domain

77130C Characterization of Precision Oscillators: Frequency Domain

77131C Characterization of Precision Oscillators: Frequency Domain, High-Accuracy Option

77140S Special Time/Frequency Measurements:

Oscillators and Other Components

Precision Oscillator Frequency

Calibration (77100C)

Precision oscillators can be readily

calibrated in the frequency range

from 1 to 100 MHz. Reference cali- bration accuracy is nominally that of

the NIST primary frequency stan- dard, that is, 8x 10 The accuracy

level transferable to the oscillator depends upon the stability and noise

properties of the oscillator.

Characterization of Atomic Time and

Frequency Standards (771 IOC)

An atomic standard is characterized

by introducing it as a member of the

NIST time scale system. The clock

output is sampled every 2 hours in sequence with the other regular

clocks in the time scale. The data are logged in the NIST time scale computer and the characteristics of the standard are readily determined in re- lation to the performance of the time

scale ensemble of clocks. At additional cost, the user can be given an account on the NIST time scale computer through which the data may be

accessed in real time. The standard

test involves 30 days of data acquisition. The square root of the Allan

variance, cry(T), is measured to ±2x 10 '-T~'^- for averaging times of

about 7200 to 10* seconds. The time

scale accuracy is about 1 X 10" and

frequency drift is less than one part in 10" per day. The actual values trans- ferable to the standard depend on its stability and noise properties.

Characterization of Precision Oscillators: Time Domain (77120C)

For oscillator frequencies of 5, 10, and 100 MHz, the stability in terms

of (Ty(T) is determined by repeated

measurements at 3-second intervals. The square root of the Allan

variance, ary(r), is measured to ±2X

IQ 12^ 1/2 j-Qj. averaging times of 1 to approximately 10,000 seconds, and

frequency offset is measured to about

1 X 10"". As noted under the description of tests 77100C and 771 IOC, the

transferable accuracy depends upon

the stability and noise properties of

the calibrated oscillator.

Characterization of Precision Oscillators: Frequency Domain (77130C)

For oscillator frequencies of 5, 10, and 100 MHz, phase noise S<(,(f) can

177
be determined for Fourier frequency

offsets from the carrier of 0. 1 Hz to 300 kHz (higher by special request).

The phase noise is measured for only

a few user-specified frequency offsets. For an offset of 1 Hz, S<j,(0 can be

measured to — 115 dB (relative to 1 radianVHertz) and for an offset of 10 kHz, S,|Xf) is measured to — 175 dB.

Characterization of Precision

Oscillators: Frequency Domain,

High-Accuracy Option (77131C)

For a pair of identical oscillators within a limited range of Fourier off- set frequencies, phase noise, 84,(0 can be measured with an error not ex- ceeding ±0.6 dB. For this accuracy,

the frequency offset must lie between

20 Hz and 10 kHz. In other respects

this service is the same as 77130C.

Special Time/Frequency Measurements: Oscillators and Other Components (77140S)

Frequency and time domain measure- ments can be made at frequencies

other than those cited in tests 77120C

and 77130C, but the accuracy and

cost are dependent upon the value of

the frequency. Given two or more

oscillators, synthesizers or amphfiers,

relative phase noise can be measured

to a very high precision and the fre- quency for the measurement is not as restrictive as above. Also, the one PPS (pulse per second) output of

atomic frequency standards can be

measured with an accuracy of 0.5 nanoseconds given an adequately defined, fast pulse.

Reference—Oscillator Characterization

Properties of Signal Sources and

Measurement Methods, D. A.

Howe, D. W. Allan, and J. A.

Barnes, Proc. 35th Ann. Freq.

Control Symp., A.l, Phil. (May

1981).

1 78
ALPHABETICAL CROSS-INDEX

Item Test Number

Absolute pressure transducers 30010C-30011C

Accelerometers 24010C-24060S

Ac-dc thermal converters (100 Hz to 1 GHz) 53405S-53445S

Ac-dc thermal converters (to 1 MHz) 53310S-53341C

Ac-dc wattmeters 56110S-56210M

Ac resistors 51410S

Ac voltmeters, high-accuracy 53200S

Acoustic emission transducers and sensors 26200C-26210S

Acoustic devices 25060S

Acoustic measurements 25010C-25070S

Activation detector dosimetry 44070C-44090C

A/D or D/A data converters 53500S-53540S

Airspeed measurements 19010C-19040S

Alpha-particle-emitting solid sources 43030C-43050C

Aluminum ultrasound reference blocks 26030S-26060S

American Petroleum Institute gages 12010C

Amplitude reference blocks 26030S-26070S

Analog-to-digital data converters 53500S-53540S

Anemometers 19010C-19040S

Angle gage blocks 14010C

Angle generators 14060S

Angular measurements 14010C-14060S

Antenna parameter measurements, microwave 63100S-63400S

Attenuators, rf and microwave 61210S-61250S

Audiofrequency phase meter 55120C-55141C

AutocoUimators 14050S

Balls 11030S

Barometers 29035 C,

30010C-30011C

Bearing-angle indicators 55210C-55221C

Beckmann thermometers 31080C

Beta particle applications 47030C^7040S

Beta-particle-emitting sources 43060S-43070S,

47030C-47040S

Calipers 12040S

Calorimetric thermometers 31070C, 33030C

Capacitance and inductance measurements, high-frequency 52210S-52310S

Capacitance and inductance measurements, low-frequency 52110S-52181C

Capacitive voltage dividers 54310S-54311S

Capacitors, dielectric 52130C

Capacitors, high-frequency 52210S-52223S

Capacitors, low-frequency 52110S-52171C

Capacitors, power-frequency 52400C

Coaxial attenuators 61210C-61211C

Coaxial power meters 61110S-61128S

Coaxial terminations and reflection coefficients 61310S-61330S

179
Color temperature 37140C-37160C

Conical plug and ring gages 12020S

Converters, A/D and D/A 53500S-53540S

Cryogenic flow measurements 18800S

Cryogenic temperature measurements 33030C-331OOS

Current and voltage transformers 54510C-54600S

Data converters, A/D and D/A 53500S-53540S

Dc resistance measurements 51100S-51163C

Dc voltage measurements 53110S-53190S

Deadweight piston gages 29010C

Density measurements, liquids 17040S

Density measurements, solids 17030S

Detector standards, windowed photodiode 40560C-40561C

Detector standards, windowless photodiode 40510C-40540C

Detectors, near ultraviolet to soft x-ray region 40599S

Deuterium arc lamps 40030C

Deuterium lamps 39050C

Dew-point hygrometers 36010C-36020C

Diameter measurements 11010S-11080S

Differential pressure transducers 30020C-30021C

Digital-to-analog data converters 53500S-53540S

Dimensional metrology 10010C-14060S

Dividers, capacitive 54310S-54311S

Dividers, inductive 54110S-54131C

Dividers, mixed 54410S

Dividers, resistive 54210C-54214S

Dosimeters, electron-beam 48010M-48020S

Dosimeters, high-dose 49010C-49050S

Dosimeters, radiochromic 49010C-49030C

Dosimeters, special tests of 44100S

Dosimeters, spectrophotometric reading 49040S-49041S

Dosimeters, x-ray, gamma-ray, and electron. 46010C-48020S

Dosimetry, neutron 44010C-^100S

Earphones 25070S

Electromagnetic field strength parameter measurements 64100S-64400S

Electrometers 46030S

Electron beam dosimetry 48010M^8020S

End standards of length 11060S

Energy and power measurements, low frequency 56110S-56210M

Ferrous-ferric dosimeters 48010M-48011M

Field strength measurements, electromagnetic 64100S-64400S

Filament lamps, ribbon 35050C-35060C,

39010C-39020C

Filters, spectral transmittance 38010C-38040C

Fixed-point devices, thermometric 33110S

Flats, optical reference 13010S

Flow measurements, cryogenic 18800S

Flow rate meters, liquid and gas 18010C-18050S

Flux standards, luminous 37080C-37130C

Force transducers 23010C-23260S

Frequency and time measurement services 76100S-76110S

180
Frequency domain 77131C

Gage blocks lOOlOC

Gages, API 12010C

Gages, ionization 30032C-30034C

Gages, low-pressure 30040S

Gages, molecular drag 30030C-30031C

Gages, piston 29010C-29020C

Gages, plug IIOIOS

Gages, plug and ring 12030S

Gages, pressure 29010C-29040S

Gages, ring 11040S

Gages, step 11070S

Gages, two-dimensional 12070S

Gages, vacuum 30010C-30050S

Gamma-ray dosimeters 46010C-46021C

Gamma-ray-emitting sources 43010C-43020C,

47010C-^7011C

Gas flow meters 18050S

Gear measuring wires 11020C

Germaniimi resistance thermometers 33060S

Global time service 76110S

ffigh-dose dosimetry 49010C^9050S

High-frequency standard capacitors and inductors 52210S-52223S

High-frequency standard resistors 51310S

High-vacuum gages 30030C-30034C

High-voltage resistors 51210C

Humidity measurements 36010C-36070S

Hydrometers 16010C

Hygrometers 36010C-36070S

Impedance measurements 52110S

Impulse generator spectrum amplitude 65100S

Impulse response of coaxial networks 65300S

Indexing tables 14030S

Inductance and capacitance measurements, low-frequency 52110S-52150C

Inductance and capacitance measurements, high-frequency 52210S-52310S

Inductive voltage dividers 54110S-54131C

Intensity standards, luminous 37010C-37070C

Internal diameter standards 11040S

Ionization chambers 47036C

Ionization gages 30032C-30034C

Irradiance sources 39040C-39050C,

40010C-40030C

Kerr cells 54410S

Laboratory thermometers 31010C-31160S

Lamps, deuterium arc 39050C-40030C

Lamps, incandescent 37010C-37140C

Lamps, quartz-halogen 39040C-39045C

Lamps, ribbon filament 35050C-35060C,

39010C-39030C

Laser power and energy measurements 42110C-42170S

Leak artifacts 30060S

181
Length and diameter, special tests 11050S

Length measurements 10010C-10060S

Length standards 10050S

Line standards 10020C

Liquid flow meters 18010C-18050S

Liquid-in-glass thermometers 31010C-31160S

Load cells 23010C-23260S

Luminous directional transmittance standards 37170C

Luminous intensity and flux standards 37010C-37130C

Luminous iQtensity of retroreflectors 38070M

Luminous transmittance standards 37170C

Manometers 29035C

Mass measurements 22010C-22180M

MEASUREMENT ASSURANCE PROGRAMS

Dc resistance 51110M

Dc voltage ...53120M

Dose interpretation of ferrous-ferric dosimeters 48010M-48011M

Laser power and energy 42120M,42140M,

42150M

Mass 22180M

Platinum resistance thermometry 33120M

Retroreflectance 38070M-38074M

Transmittance 38080M

Watthour meters 56210M

Mercurial barometer and manometers 29035

Meteorological airspeed instrumentation 19030S

Meters, flow rate 18030C

Meters, laser power and energy 421 IOC, 42170S

Meters, optical fiber power 42130C, 42140M,

42180S

Meters, phase 55110S-55141C

Meters, power 61110S-61190S

Meters, turbine 18010C-18020C

Microcopy resolution test charts 38100S

Micrometer screws and dial micrometers 12050S

Microphones, pressure and free-field response 25010C-25050C

Micropotentiometers, rf 53440S-53445S

Microwave antenna parameter measurements 63100S-63400S

Mixed voltage dividers 54410S

Molecular drag gages 30030C-30031C

N-port scattering measurements 61520S

Neutron dosimeters 44100S

Neutron sources 44010C-^020C

Noise temperature measurements, coaxial and waveguide 62020S-62140S

Oil gaging and surveying tapes 10030C

Opal glass transmittance standard 37170C

C^tical fiber power meters 42130C-42140M,

42180S

Optical flats 13010S

Optical polygons 14020S

182
Optical pyrometers 35010C-35040C

Optical reference planes 13010S

Oscillator characterization 77100C-77140S

Penetrameters, x-ray 46040S

Penetration needles 12060S

Personnel protection instrumentation 44060C

Phase measurements 55110S-55230S

Phase shifters, rf and microwave 61410S-61450S

Photodiode spectral response 39070C

Photodiodes, windowed and windowless 40510C-40560C

Photographic step tablets 38090S

Photometric tests, special 37180S

Photometry 37010C-37180S

Pickup sensitivity 24010C-24030C,

24050C

Piston gages, controlled clearance. 29020C

Piston gages, deadweight 29010C

Pitot-static tubes 19010C

Platinum resistance thermometers 33010C-33050C

Plug and ring gages 12010C-12030C

Plug gages IIOIOS

Pneumatic bridge hygrometers 36060C

Polygons, optical 14020S

Power and energy measurements, low-frequency 56110S-56210M

Power meters, optical fiber 42130C-42140M,

42180S

Power meters, rf and microwave 61110S-61190S

Pressure gages and transducers 29030C

Pressure gages, low absolute 30010C-30011C

Pressure gages, low differential 30020C-30021C

Pressure gages, special tests 29040S

Pressure measurements 29010C-29040S,

30010C-30060S

Proving rings 23010C-23260S

Pulse voltage measuring systems 54410S

Pulse waveform measurements 65100S-65400S

Pyrometer indicators 32100C

Pyrometers, optical 35010C-35040C

Pyrometers, radiation 35070S

Q-standards 52710C-52711C

Quartz-halogen lamps 39040C-39045C

Radiance standard sources 39010C-39030C,

40020C

Radiant energy detectors 39070C

Radiation detectors 46010C-^6011C

Radiation pyrometers. 35070S

Radiation thermometry 35010C-35070S

Radioactive sources, alpha-emitting 43030C-43050C,

43090S

Radioactive sources, beta-emitting 43060S-43070S

Radioactive sources, gamma-emitting 43010C-43020C

183
Radioactive sources, neutron-emitting 44010C-44020C

Radiochrometric dosimeters 49020C-49030C

Radiometric detectors, special tests 39080S

Radiometric measurements 39010C-39080S,

40010C^0040S,

40510C-40599S

Radionuclides 43010C-^3090S

Reference block measurements, ultrasonic 26030S-26070S

Reflection coefficients, coaxial and waveguide terminals 61310S-61330S

Resistance measurements, dc 51100S-51163C

Resistance thermometers 33010C-33100S

Resistive voltage dividers 54210C-54214S

Resistors, ac 51410S

Resistors, high-frequency 51310S

Resistors, high-precision standard, dc 51130C-51154C

Resistors, high-voltage 51210C

Resistors, megohm 51142C-51150C

Resistors for current measurements. 51160C-51163C

Retroreflectors, coefficient of luminous intensity 38070M-38074M

Ribbon filament lamps 35050C-35060C

Ring gages 11040S

R-meters 46010C-^6011C

Rods, surveying leveling 10040S

Rotary and indexing tables 14030S

Roughness specimens 15010C-15020C

Roundness measurements 13020S-13030S

Saturated standard cells 53130C-53131C

Scattering measurements, 2-port 61520S

Shock measurements 24040S

Sieves, special tests of 10060S

Sources, high-accuracy, ac voltage 53200S

Spectral irradiance 39040C-39050C,

40010C, 40030C

Spectral irradiance, lamps 39040C-39050C

Spectral radiance 39010C-39030C,

40020S

Spectral radiance, lamps 39010C-39030C

Spectral response, photodiode 39070C

Spectral transmittance filters 38010C-39040C,

38060S

Spectrophotometric standards 39010C-39080S

Spherical diameter standards, balls 11030S

Standard voltage cells 53130C-53150C

Step gages, length 11070S

Step height measurements 15030C

Step tablet density, photographic 38090S

Surface roughness standards 15020C

Surveying and oil gaging tapes 10030C

Surveying leveling rods, special tests of 10040S

Thermal voltage and current converters (100 Hz-1 GHz) 53405S-53445S

Thermal voltage converters (to 1 MHz) 53310S-53341C

184
Thermocouples and thermocouple materials 32010C-32150S

Thermometers, Beckmami 31080C

Thermometers, calorimetric 31070C, 33030C

Thermometers, cryogenic 33060S

Thermometers, germanium resistance 33060S

Thermometers, laboratory 31010C-31260S

Thermometers, platinum resistance 33010C-33050C

Thermometric fixed-point devices 33110S

Thermometry, radiation 35010C-35070S

Thread measuring wires 11020C, 11080S

Threaded plug and ring gages 12030S

Time and frequency measurement services 76100S-76110S

Time domain 77120C

Transducer measurements, acoustic emission 26200C-26210S

Transducer measurements, ultrasonic 26100C-26120S

Transducers, low-pressure 30010C-30021C

Transformers, voltage and current 54510C-54600S

Transmittance, luminous directional 37170C

Transmittance, Measurement Assurance Program 38080M

Transmittance filters, spectral 38010C-38040C

Turbine flow meters 18010C-18020C

Two-port scattering measurements 61520S

Ultrasonic reference block measurements 26030S-26070S

Ultrasonic system power, calorimetric 26110C

Ultrasonic transducer measurements 26100C-26120S

Ultrasonic transducer power, radiation pressure 26100C

Ultraviolet detectors 40510C-40599S

Ultraviolet sources 40010C^0040S

Unsaturated standard cells 53150C

Vacuum gages 30030C-30034C,

30O50S

Vacuum measurements 30010C-30050S

Vacuum ultraviolet radiometric measurements 40010C-40040S

Velocity reference blocks 26070S

Very-high-frequency omnidirectional range (VOR) measurements 55210C-55230S

Vibration and shock measurements 24010C-24060S

Voltage, ac 53200S

Voltage, dc 53110S-53190S

Voltage, rf-dc 53405S-53445S

Voltage and current transformers 54510C-54600S

Voltage dividers, capacitive 54310S-54311S

Voltage dividers, inductive 54110S-54131C

Voltage dividers, mixed 54410S

Voltage dividers, resistive 54210C-54214S

Voltage reference standards, solid state 53160C-53161C

Voltmeters, high-accuracy, ac 53200S

Volume standards 17010C-17020S

VOR measurements 55210C-55230S

Watthour meters 56200C-56210M

Wattmeters 56110S-56121C

Waveform measurements, pulse 651008-654005

185
Waveguide attenuators 61230S

Waveguide power meters 61140S-<)1155S

Waveguide terminations and reflection coefficients 61320S-61330S

Wavelength standards 38050C

Wedges 14040S

Weights (mass standards) 22010C-22180M

Wires for thread and gear measurements 11020C, 11080S

X-ray and photographic step tablets 38090S

X-ray dosimeter 46010C-46050S

X-ray penetrameter 46040S

X-ray resolution test charts 38100S

186
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