NATL INST. OF STAND & TECHI RJ.fi

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isurement Services:

MIST

PUBLICATIONS

Radiance Temperature Calibrations

U.S. Department of Commerce

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100 National Institute of Standards and Technology

U57

!0 250-43

I988
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NIST Special Publication 250-43

NIST MEASUREMENT SERVICES:

Radiance Temperature Calibrations

Charles E. Gibson, Benjamin K. Tsai, and Albert C. Parr

Optical Technology Division

Physics Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-0001

January 1998

U.S. DEPARTMENT OF COMMERCE

William M. Daley, Secretary

Technology Administration

Gary R. Bachula, Acting Under Secretary for Technology

National Institute of Standards and Technology

Raymond G. Kammer, Director
National Institute of Standards and Technology Special Publication 250-43

Natl. Inst. Stand. Technol. Spec. Publ. 250-43, 123 pages (Jan. 1998)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1998

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
PREFACE

The calibration and related measurement services of the National Institute of Standards and

Technology are intended to assist the makers and users of precision measuring instruments in achieving the highest possible levels of accuracy, quality, and productivity. NIST offers over 300

different calibrations, special tests, and measurement assurance services. These services allow

customers to directly link their measurement systems to measurement systems and standards

maintained by NIST. These services are offered to the public and private organizations alike.

They are described in NIST Special Publication (SP) 250, NIST Calibration Services Users

Guide.

The Users Guide is supplemented by a number of Special Publications (designated as the "SP250

Series") that provide detailed descriptions of the important features of specific NIST calibration

services. These documents provide a description of the: (1) specifications for the services; (2)

design philosophy and theory; (3) NIST measurement system; (4) NIST operational procedures;

(5) assessment of the measurement uncertainty including random and systematic errors and an

error budget; and (6) internal quality control procedures used by NIST. These documents will

present more detail than can be given in NIST calibration reports, or than is generally allowed in

articles in scientific journals. In the past, NIST has published such information in a variety of

ways. This series will make this type of information more readily available to the user.

This document, SP250-43 (1997), NIST Measurement Services: Radiance Temperature

Calibrations, is a revision of SP250-7 (1987). It covers the calibration of radiance temperature

standards for disappearing filament optical pyrometers, ribbon filament lamps, and radiation

thermometers (test numbers 35010C-35070S in SP250, NIST Calibration Services Users Guide).

Inquiries concerning the technical content of this document or the specifications for these

services should be directed to the author or to one of the technical contacts cited in SP250.

NIST welcomes suggestions on how publications such as this might be made more useful.

Suggestions are also welcome concerning the need for new calibrations services, special tests, and measurement assurance programs.

Stanley D. Rasberry

Director

Measurement Services

Katharine B. Gebbie

Director

Physics Laboratory

iii
ABSTRACT

This document describes the realization and dissemination of the International Temperature Scale

of 1990 (ITS-90) above 700 °C at the National Institute of Standards and Technology (NIST). By

using fundamental principles of blackbody physics, the ITS-90 scale is first fixed at the freezing

point of gold (790= 1064.18 °C) and is then extended to temperatures between 700 °C and

2700 °C by determining the ratio of the spectral radiance of a tungsten ribbon filament lamp to

that of a gold fixed-point blackbody at a wavelength of 655.3 nm. A description of the facilities

in the NIST Radiance Temperature Calibration Laboratory is given, along with a discussion of

the wavelength calibration, size of source, and linearity issues. The use and calibration of

radiance temperature standards are explained. Values of stability and uncertainties in the scale are reported. The expanded uncertainties (k = 2) at 800 °C and 2300 °C are 0.6 °C and 1.4 °C for

ribbon filament lamps, 4 °C and 7 °C for disappearing filament optical pyrometers, and 2 °C and

3 °C for infrared radiation thermometers.

KEYWORDS: gold-point blackbody, International Temperature Scale (ITS-90),

pyrometers, pyrometry, radiance temperature calibration, radiation

thermometry, tungsten ribbon filament lamps

iv
TABLE OF CONTENTS

Abstract iv

1. Introduction 1

2. Measurement theory 4

3. Realization of the U.S. national scale of radiance temperature 9

3. 1 1990 NIST scale of radiance temperature 9

3.2 Temperature standards 9

3.2.1 Gold-point blackbody 9

3.2.2 Tungsten ribbon filament lamps 11 3.2.3 Working standard lamps 14

3.2.4 Variable-temperature blackbody 15

3.3 NIST photoelectric pyrometer 19

3.3.1 Measurement system 19

3.3.2 Optical system 21

3.3.3 Interference filters 22

3.3.4 Detectors 23

3.3.5 Linearity of response 24

3.3.6 Wavelength calibration 27

3.3.7 Size of source effect 29

3.4 Radiance temperature scale uncertainties 30

3.5 Quality control 32

4. Tungsten ribbon filament lamp calibrations 37

4. 1 Lamp preparation 37

4.2 Lamp calibration 37

4.3 Lamp data analysis 38

4.4 Lamp calibration uncertainty 40

5. Disappearing filament optical pyrometer calibrations 44

5.1 Optical pyrometer preparation 44

5.2 Optical pyrometer calibration 44

5.3 Optical pyrometer data analysis 44

5.4 Optical pyrometer calibration uncertainty 45

v
TABLE OF CONTENTS (continued)

6. Radiation thermometer calibrations 49

6.1 Radiation thermometer preparation 49

6.2 Radiation thermometer calibration 49

6.3 Radiation thermometer data analysis 49

6.4 Radiation thermometer calibration uncertainty 49

7. Modifications to the NIST photoelectric pyrometer 53

Acknowledgments 54

References 55

Appendix A: Ribbon filament lamp sample calibration report Al

Appendix B: Optical pyrometer sample calibration report B

Appendix C: Radiation thermometer sample calibration report CI

Appendix D: Radiance temperature measurement services laboratory procedure manual Dl

Appendix E: How to request radiance temperature calibration services El

vi
LIST OF FIGURES

Figure 1 Schematic of optics for the NIST photoelectric pyrometer 4

Figure 2 Blackbody spectral distribution. As the temperature increases, the peak moves

toward shorter wavelengths, and the slope increases at each wavelength 5

Figure 3 Schematic of gold-point blackbody 10

Figure 4 Gold-point blackbody liquid-to-solid phase transition 1

Figure 5 Gold-point blackbody control system 12

Figure 6 Schematic of lamp current monitoring system 13

Figure 7 Typical lamp currents for the General Electric 30A/T24/6 ribbon filament lamp 14

Figure 8 Ribbon filament lamp 16

Figure 9 Calibration history of the working standard (no. SL20) 17

Figure 10 Schematic of the variable temperature blackbody 17

Figure 1 1 Variable temperature blackbody control system 18

Figure 12 Spatial scan of the variable temperature blackbody at 2000 °C. The temperature

differences are from the center position (0,0) 18

Figure 13 Variable temperature blackbody PID control. After decreasing the set point by

100 °C, the blackbody stabilizes in less than 10 min 19

Figure 14 NIST photoelectric pyrometer 20

Figure 15 NIST radiance temperature laboratory measurement system 21

Figure 16 NIST photoelectric pyrometer filter transmittances. The wavelength of the

pyrometer is selected by using a 1 nm and a 10 nm spectral bandwidth (SBW)

filter 22

Figure 17 The linearity correction factors for the PEP 25

Figure 18 Relative spectral response of the NIST photoelectric pyrometer 28

Figure 19 The size of source corrections for the variable temperature blackbody to the

working standard lamp comparison and the working standard lamp to the

gold-point blackbody 30

Figure 20 Calibration history of the ribbon filament lamp check standards 35

Figure 21 Calibration history of the radiation thermometer check standard

(Minolta Cyclops 52) 36

Figure 22 Calculation of 7COrr from Tmean and AI/AT 39

Figure 23 Graph of rmean and AI/AT 40

Figure 24 Modified NIST photoelectric pyrometer 53

vii
LIST OF TABLES

Table 1 Radiance temperature calibration services 2

Table 2 Calibration uncertainties 3

Table 3 Current amplifier normalization factors 24

Table 4 Detector system correction factors and linearity coefficients 25

Table 5 Default hardware settings used by calibration program 26

Table 6 Corrections (°C) to the radiance temperature at 900 nm and at 1000 nm 29

Table 7 Typical values of WS variables and parameters 33

Table 8 Uncertainty budget for the NIST WS lamp spectral radiance realization 34

Table 9 Typical values of TL variables and parameters 42

Table 10 Uncertainty budget for the TL spectral radiance calibration 43

Table 1 1 Typical values of DF variables and parameters 47

Table 12 Uncertainty budget for the DF spectral radiance calibration 48

Table 1 3 Typical values of RT variables and parameters 51

Table 14 Uncertainty budget for the RT spectral radiance calibration 52

viii
1. Introduction

The National Institute of Standards and Technology (NIST) is responsible for the

establishment, maintenance, and dissemination of the U.S. National Scale of Radiance

Temperature through its Radiance Temperature Calibration Laboratory (RTCL), which provides

temperature measurements above 700 °C. The 1990 NIST Radiance Temperature Scale [1] is based upon the NIST realization of the International Temperature Scale 1990 [2] using principles

from blackbody physics. Beginning with the determination of the freezing point of gold

(T9o = 1064.18 °C), the scale is realized for the range from 700 °C to 4200 °C using radiometric

methods. The radiance temperature (also referred to as the brightness or apparent temperature)

of a radiator is equivalent to the temperature of a blackbody with the same radiant intensity as

that of the radiator's surface at a chosen wavelength.

This document describes the determination of the ratio of the spectral radiance of a tungsten ribbon filament lamp used as a temperature standard to that of a gold fixed-point

blackbody at a wavelength of 655.3 nm. A description of the NIST RTCL along with the use and

calibration of radiance temperature standards therein is presented in detail. Issues relating to the

wavelength calibration, size of source, and linearity of the NIST Photoelectric Pyrometer (PEP)

are then discussed. Stability and uncertainties in the scale are considered in detail within the

framework of the NIST policy on uncertainty statements described in reference [3].

The NIST disseminates the radiance temperature scale by two methods. The first method

involves calibrating ribbon filament lamps as radiance temperature standards in the temperature

range from 800 °C to 2300 °C with expanded uncertainties (k = 2)

[ of 0.6 °C at 800 °C, and

1.4 °C at 2300 °C. The second method involves the calibration of customer pyrometers and

radiation thermometers. Disappearing filament optical pyrometers are calibrated from 800 °C to 4200 °C with expanded uncertainties (k = 2) of 4 °C at 800 °C, 7 °C at 2300 °C, and 25 °C at 4200 °C. Radiation thermometers are measured from 800 °C to 2700 °C with expanded

uncertainties (k = 2) of 2 °C at 800 °C, and 3 °C at 2700 °C.

The radiance temperature calibration services shown in Table 1 are offered through the

NIST Calibration Services Program and are listed in the Radiation Thermometry section of the

Thermodynamics Quantities Chapter of the NIST Calibration Services Users Guide [4]. A

summary of the calibration uncertainties is given in Table 2. This laboratory's quality system is based on the ANSI/NCSL Z540-1-1994 standard and the ISO/TEC Guide 25.

Throughout this paper, all uncertainty values are given as an expanded uncertainty with

coverage factor k = 2, thus a two standard deviation estimate. Uncertainties of fundamental units

given as a combined standard uncertainty in other documents are restated as an expanded

uncertainty (k = 2).

1
Table 1. Radiance temperature calibration services

Service ID No. Measurement Description

Calibration reports are issued giving the radiance temperature of the blackbody at 655.3 nm

versus the scale reading, output current, or output voltage.

350 IOC Radiance Temperature Standard, Disappearing Filament Optical Pyrometer

(800 °C to 2400 °C, 4 to 12 points, 1 range)

35020C Radiance Temperature Standard, Disappearing Filament Optical Pyrometer

(each additional range up to 4200 °C, only available with No. 350 10C)

35030C Additional Interpolated Values

35040C Radiance Temperature Standard, Disappearing Filament Optical Pyrometer

(800 °C to 4200 °C, 3 or fewer points, 1 range)

Calibration reports are issued giving the radiance temperature of the lamp at 655.3 nm versus

the lamp current.

35050C Radiance Temperature Standard, Ribbon Filament Lamp (800 °C to 2300 °C, 6 to 16 points)

35060C Radiance Temperature Standard, Ribbon Filament Lamp (800 °C to 2300 °C, 5 or fewer points)

Test reports are issued giving the radiance temperature of the blackbody at 655.3 nm, 900 nm,

or 1000 nm versus the indicated reading, output current, or output voltage.

35070S Special Tests of Radiation Thermometers
Table 2. Calibration uncertainties

Standard Temperature Range

JJ/A UcUlllCU1 Jncprtaintv

Ribbon filament lamp 800 °C to 1600 °C 0.7 °C

1600 °C to 1900 °C 1.0 °C

1900 °C to 2300 °C 1.5 °C

Leeds & Northrup 800 °C to 1600 °C 4°C

Model 8000 series 1600 °C to 2100 °C 5°C

1900 °C to 2300 °C 7°C

Disappearing filament 2400 °C to 2700 °C 8 °C

optical pyrometer 2700 °C to 3200 °C 17 °C

3200 °C to 4200 °C 25 °c

Pyrometer Instrument 800 °C to 1400 °C 3 °C

Model 95 1400 °C to 1800 °C 4 °C

1800 °C to 2400 °C 5 °C

Disappearing filament 2400 °C to 2700 °C 8°C

optical pyrometer 2700 °C to 3200 °C 12 °C

Infrared radiation 800 °C to 2000 °C 2°C

thermometer 2000 °C to 2700 °C 3 °C

The expanded uncertainty (coverage factor k = 2) is equivalent to a two standard deviation estimate.

3
2. Measurement theory

Temperatures above the freezing point of silver (1234.93 K or 961.78 °C) are defined on

the International Temperature Scale of 1990 (ITS-90) [2] in terms of the ratio of spectral

radiances of two blackbody sources, one of which is maintained at the temperature of freezing

silver, gold (1337.33 K or 1064.18 °C), or copper (1357.77 K or 1084.62 °C). The 1990 NIST

Scale of Radiance Temperature (1990 NIST) is a realization of the ITS-90 using a gold fixedpoint blackbody. In this section, the blackbody temperature will be defined in terms of the

spectral radiance. Using the signal measurement equation, the measurement equation for the

calibration of a transfer standard will be derived.

The signal measurement equation, defined by Nicodemus and Kostkowski in 1978 [5],

relates the detector signal output, S [V] , to the source flux input parameters through a detector

responsivity term, Rx [A W 1 ], by the integral relationship,

S =

J

j* J

Rx LA

• dA • cos 6 dco 6A , (1)

A a A

I

LEGEND

AS Aperture Stop CL Collimating Lens DL Diverging Lens

Fl 1 nm bandwidth interference filter F2 10 nm bandwidth interference filter FS Field Stop

OL Objective Lens

Figure 1. Schematic of optics for the NIST photoelectric pyrometer.

2 As an aid to the reader, the appropriate coherent SI unit in which a quantity should be expressed

is indicated in brackets when the quantity is first introduced.

4
where Lx [Wm^sr 1 ] is the spectral radiance, dA [m] is the wavelength band, 9 [rad] is the angle

between the aperture normal and the line connecting the aperture centers, do [sr] is the

differential solid angle originating at the source aperture as defined by the detector aperture, and

dA [m2

] is the differential source aperture area. For the NIST PEP in figure 1 , the spectral

responsivity Rx includes the spectral transmittance of the interference filters, the spectral

transmittance of all other optical elements, and the spectral responsivity of the detector. In terms

of its specific components, the spectral responsivity is

where txol is the spectral transmittance of the objective lens, Ta,cl is the spectral transmittance of

the collimating lens, t^fi is the spectral transmittance of the 1 nm bandpass interference filter,

Ta,f2 is the spectral transmittance of the 10 nm bandpass interference filter, t^dl is the spectral

transmittance of the diverging lens, Ta,ec is the spectral transmittance of the evacuated window

cell, and Rx,pep is the detector absolute spectral responsivity.

200 600 1000 1400

Wavelength (nm)

1800 2200

Figure 2. Blackbody spectral distribution. As the temperature increases, the peak moves towards shorter wavelengths, and the slope increases at each wavelength.

5
Spectral radiance La is the radiant power contained in a defined area, solid angle,

direction, and wavelength interval,

LA = d

3 0 / dA cos a dp dX , (3)

where <Z> is the radiant flux [W], A is the source area, a is the plane angle between the surface

normal and the direction of propagation [rad], (3 is the solid angle about that direction [sr], and X

is the wavelength [m]. A few blackbody distributions from 250 nm to 2500 nm between 800 °C

and 2300 °C are illustrated in figure 2. For an ideal blackbody in a vacuum environment,

the relation between spectral radiance, wavelength, and temperature is given by the Planck

equation [6],

T -

CJk (A)

X

5

• (exp(c2 /(X • T)) - 1) '

{ )

where c\i is the first radiation constant in radiance form with a value of 1 19.1044 Wnm2

, ci is the second radiation constant with a value of 1.4388 x 10"7 nm-K [7], X is the wavelength in

vacuum, and T is the temperature [K]. The Planck equation in the form of eq (4) is the definition

for an ideal blackbody radiator. When using a non-ideal blackbody such as a fixed-point

blackbody to realize the temperature scale, the following form of the Planck equation is used,

L =

£x ' °XL (5)

n\ X

5 (exp(c2 l(nx X • T)) - 1)

'

and temperature is defined as a function of spectral radiance using the following equation

T(X, LA

) = t ^ . , (6) nx X \n{\ + ek clL I nk X Lj

where £x is the spectral emissivity of the blackbody (which is equal to unity in the case of an

ideal blackbody), A is the wavelength in air, and nx is the refractive index of air at 15 °C and

101,325 Pa. From the Cauchy [8] formula,

n x =1 + (2726.43 + 12.288 nm

2 /(A2 xl0-6 )+ 0.3555 nm

4 /(A4 xlO" 12 ))xlO"

7

, (7)

the refractive index of air at 655.3 nm is about 1.00028. The temperatures described in this

document are radiance temperatures. The radiance temperature of a radiator is equivalent to the

temperature of a blackbody with the same radiant intensity of the radiator's surface at a specified

wavelength. The relationship between the radiance temperature and the true or thermodynamic

temperature of a blackbody is given by:

6
where 7 is the thermodynamic temperature, 7\ is the radiance temperature, X is the mean

effective wavelength of the NIST PEP (655.3 nm), and £\ is the estimated emissivity of the

blackbody (0.99).

Determination of the spectral radiance temperature of a working standard (WS) lamp

requires measurement of the ratio r\,

rx =

'WS

' Ail (9)

of the signals from the transfer standard and the goldpoint blackbody (Au) with the NIST PEP.

From eq (2), this measured ratio is actually

\\\RX {LX cos0s dmdAXs dA

X As (o \\\RX {LX cos0s dft> dAs )Au dA

'

To simplify the complex expression in eq (10), it is assumed that the spectral radiances L^ws and

Lx,Au, spectral responsivities ^a,ws and R^au, and amplifier gains Gws and Gau are independent of

both direction and spatial location. Furthermore, these three variables can be defined by unique

for the transfer source and the gold-point blackbody at equivalent wavelengths (to be defined

later) over the same small wavelength band dA. The solid angle terms can be replaced with the

definition of the solid angle,

D

where Ad is the detector area [m2

], 0d is the angle between the optical axis and the normal to the

detector surface [rad], and D is the distance between the detector area and the source area [m].

Assuming that the areas are independent of direction and that the solid angles are independent of

area or spatial location, this ratio then becomes

ri =

cos 6S cos Ge

cos 6d ), cos 6d )

D

D

Au (12)

WS

where As is the source area [m2

], 0S is the angle between the optical axis and the normal to the source surface [rad], /?a,ws is the detector responsivity when viewing the transfer source, and

Rx,au is the detector responsivity when viewing the gold-point blackbody. The spectral

responsivities /?a,ws and 7?a,au are assumed to be equal. If the source aperture areas dATs and

7
(Mau, source solid angles da>ws and dfi)Au, and the source inclination angles 9ws and 0au are the

same for measuring both the transfer standard and the gold-point blackbody, the measured ratio

simplifies to the expression,

L'A,WS (Xws

)

L

(13)

'A.Au

This relationship is the defining equation for the ITS-90 above 1337.33 K. In terms of eq (4), it can be written at a discrete wavelength, X, as

where La(Tws) and L^(TAu) are the spectral radiances of the two blackbodies at temperatures T

and rAu, ?au is the temperature of freezing gold defined as 1337.33 K, and r\ is their ratio. In principle, a measurement of the ratio at a discrete wavelength with a linear response instrument

yields the value of T. The radiance temperature scale is typically maintained and disseminated on tungsten

ribbon filament lamps, which possess a repeatable lamp current versus radiance temperature

relationship. At the NIST, a pyrometer system is presently being used with a mean effective

wavelength of 655.3 nm. This method requires that the pyrometer relative spectral response

extends only over a small spectral range, or is known accurately enough to determine the

wavelength at which the integrands of eq (10) have the same ratio as the integrals. Equation (13)

above is an approximation, and, in practice, corrections, which will be presented in the next

section, are used.

M^ws) =

exp(c2 l(n x X 7Au )) — 1 M^aJ exP(c2 f

(nx rws)) - 1

' (14)

e
3. Realization of the U.S. national scale of radiance temperature

3.1 1990 NIST scale of radiance temperature

The reference temperature standard, a gold fixed-point blackbody (Au) with a temperature (Tau) of 1064.18 °C (1337.33 K), and the Planck radiation law are used to realize

and disseminate the 1990 NIST Radiance Temperature Scale. Equation (5) is used to calculate

the spectral radiance La,au (A, 7au) of the fixed-point blackbody for A = 655.3 nm in all the

measurements of this calibration facility. Measurements are performed from 800 °C to 2300 °C

for lamps, from 800 °C to 2700 °C for radiation thermometers, and extrapolated to 4200 °C for

some disappearing filament optical pyrometers.

The NIST PEP is the transfer device used to compare the spectral radiances of the sources by the direct substitution method. The signals are corrected for size of source, amplifier gain,

and linearity. With these corrections, the spectral radiance and the radiance temperature can be

determined from eqs (12) and (13). The NIST PEP is a filtered radiometer that uses two

interference filters to select the bandpass. The spectral bandwidth is 5 nm with a mean effective

wavelength of 655.3 nm. A photomultiplier tube with an S-20 spectral response is used in the dc

mode. The measurement spot size is a 0.6 mm by 0.8 mm rectangle.

A high stability vacuum lamp operated at a single radiance temperature of approximately

1255 °C is the working standard (WS). By equating eqs (9) and (13), the spectral radiance ratio is

Lx (TAu )

'WSl

'Au

(15)

After applying correction factors to the signals in eq (15) for amplifier calibration (Ca), linearity

(CO, and size of source (Cs), the spectral radiance of the WS 1 lamp can be written as

All (

2 -15 c ) nx A exp

c 2 - 1

K nx

• k TAu ^

(^A ' Cl '

' ^)\VS

(CA CL

' Q ' G)au

(16)

References regarding linearity issues are presented in Section 3.3.5. The uncertainty analysis in

Section 3.6 can then be derived from eq (15) for the NIST radiance temperature scale up to the

calibration of the spectral radiance of the working standard lamp.

3.2 Temperature standards

3.2.1 Gold-point blackbody

In the RTCL, a gold fixed-point blackbody with a calculated emissivity of 0.9999.

designed and built by the NIST Optical Technology Division, is the primary standard used to

realize the 1990 NIST Radiance Temperature Scale. The blackbody in figure 3 consists of a

graphite cavity, a crucible of gold, and a cylindrical heat-pipe furnace. The cavity, which is

9
76 mm in length and 6 mm in diameter and has a 60° conical end shown, is made from Ultra "F"

grade graphite (spectrographic purities of 10 ppm or less). Surrounding this cavity is a crucible

containing 0.99999% pure gold. The cavity, along with graphite rings and silica glass spacers, is placed in an alumina tube. The front rings define a solid angle with a f/6 field of view, while the

back rings support the thermocouple. A furnace (see fig. 3), which consists of a sodium heatpipe heated by two semi-cylindrical ceramic heater elements inside of a mullite tube, is enclosed

in a water-cooled housing (63 1 mL/min) and is operated in an argon environment (37 mL/min

with furnace door closed and 235 mL/min with furnace door open).

The gold-point blackbody liquid-to-solid phase transition is shown in figure 4. The

duration of a melt or freeze plateau is approximately 40 min, and the time delay between these

observation periods is about 45 min. Measurements during the freeze cycle show a negative

slope of 20 mK in 30 min. The blackbody is slowly heated over about 8 h before reaching the

melting point and is typically ramped up over night so that it is held just below the melting point

the next morning. After the initial heating at 8 A, the melt cycle is begun by increasing the

current to 8.5 A until the temperature reaches 1071 °C. The freeze cycle is begun by lowering

the blackbody current to 7.95 A. Then the blackbody current is raised to 8.5 A at 1050 °C to begin the melt cycle again.

1 cavity

2 crucible

3 heat pipe 4 semicyhndrical heater element

5 water cooling coil 6 graphite rings

7 silica glass spacers

8 shutter opening device

7 6 m ///,

Figure 3 . Schematic of gold-point blackbody.

10
The gold-point blackbody control system shown in figure 5 consists of a 286-based

personal computer, which regulates the power supply and reads the thermocouple measurements

from the digital voltmeter. To monitor the set points, platinum and platinum/10% rhodium

(type S) thermocouples are inserted into round double bore alumina tubing and are placed in a

silica glass sheathing which makes contact with the rear end of the crucible.

3.2.2 Tungsten ribbon filament lamps

Because of a reproducible radiance temperature versus lamp current relationship, tungsten

ribbon filament lamps are used in the radiance temperature scale realization and are issued as radiance temperature standards. Vacuum lamps are typically used for temperatures from 800 °C

to 1700 °C, and argon gas-filled lamps for temperatures from 1300 °C to 2300 °C. Gas is introduced into the high temperature lamps to slow down the evaporation rate of the tungsten.

The evaporated tungsten atoms collide with the gas atoms, lose their energy, and re-condense on

the filament surface before being swept away by convection [9].

11
DVM

LEGEND

ASA Argon Supply and Alarm

cw 55 °C Chilled Water/Cold Water Switch

DVM Digital Voltmeter

GC Gold-filled CruciPle

HPF Heat Pipe Furnace

PC Personal Computer

PS Power Supply

PT Pt/Pt-10% Rh Thermocouple (Type S)

Figure 5. Gold-point blackbody control system.

The lamps have cylindrical glass envelopes and are operated on direct current with the

base facing downward. A computer-stabilized power supply regulates the lamp current to within

± 0.2 mA. A schematic of the lamp current monitoring system is shown in figure 6. The

filament is connected to the screw base by wires, which conduct the current and thereby

minimize contact problems associated with the screw bases. To achieve the required precise

alignment, the lamps are rigidly fastened in source mounts that allow translation along and

rotation about three mutually perpendicular axes. Located at the intersection of the center of the

lamp filament at the height of the notch opening, the rectangular calibration area on the surface

of the lamp filament is 0.6 mm wide by 0.8 mm high. The notch is about midway along one edge

of the filament. An alignment mark or an etched arrow is placed on the envelope opposite the

side viewed by the pyrometer to permit reproducible angular positioning. Then the lamp is rotated so that the arrowhead is centered at the mouth of the notch.

Some lamps use a pointer that is connected to the filament support to indicate the

calibration area. The advantage to this approach is a more uniform filament. However, one

12
disadvantage is the requirement of predictable filament expansion and contraction for

reproducible calibration area indication by the pointer.

Until 1995, the NIST issued General Electric

3 type 30A/6V/T24 ribbon filament lamps

as radiance temperature standards. However, General Electric stopped manufacturing these

lamps in 1990. The lamp had a glass cylindrical envelope that was 300 mm long and 75 mm in

diameter and a filament that was 3 mm wide and 50 mm long. Figure 7 shows typical lamp

currents as a function of temperature for the General Electric ribbon filament lamps.

DAC

GPIB

LA +

GPIB

PC

LEGEND

CL Current Sensing Leads

DAC Two-channel 1 2-bit D/A Converter

DVM Digital Voltmeter

GPIB GPIB IEEE-488 Interface

LA Lamp

PC Personal Computer

PS Power Suppy

SH 0.1 a Shunt

Figure 6. Schematic of lamp current monitoring system.

Certain commercial equipment, instruments, or materials are identified in this paper for the sole

purpose of adequately describing experimental or test procedures. Such identification does not

imply recommendation or endorsement by the National Institute of Standards and Technology of

a particular product, nor does it imply that the materials or equipment identified are necessarily

the best available for the purpose it serves.

13
50

45

40

*- 35 C

0)3 30

U

o.E25

(0 -J 20

15 -

10

500 1000 1500 2000 2500

Temperature ( C)

Figure 7. Typical lamp currents for the General Electric 30A/T24/6 ribbon filament lamp.

The NIST is currently issuing U.K. General Electric Company (GEC) lamps, although the

lamps are no longer available from this source. The GEC lamps (type 20/G and 20/V) have glass

cylindrical envelopes that are 235 mm long with a 64 mm diameter. The 20/V is a vacuum lamp

with a filament 1 mm wide by 50 mm long and requires about 10 A dc at 1500 °C. The 20/G is a gas-filled lamp with a 2 mm wide by 30 mm long filament and requires about 20 A dc at 2300 °C.

In 1992, Type TRU 1100-2350 lamps were purchased from the Moscow Lamp Factory

(Russia) for testing as radiance temperature standards. Due to a decline in requests for radiance

temperature standard lamps, the testing was not done. At 2300 °C, about 25 A dc current is required from the gas-filled lamp, which has a cylindrical envelope, a 2.5 mm wide by 20 mm

long filament, and an alignment pointer. The TRU lamps, which have a 35 mm silica glass

window that projects about 5 mm from the envelope, were used in addition to the GE lamp in the

NIST/VNIOFFI spectral radiance intercomparison [10].

The NIST has also bought type 24/G lamps with double silica glass windows from

Polaron Engineering LTD (U. K.) for use as working and check standards. These lamps are similar in design and construction to the GEC lamps.

3.2.3 Working standard lamps

A vacuum tungsten ribbon filament lamp of the Quinn-Lee type [11,12] is used in the

temperature scale realization as the secondary temperature standard which maintains the

14
temperature scale between scale realizations and as the transfer standard for calibration

measurements. The temperature of the working standard lamp (serial number SL20) is determined by spectral comparison with the gold-point blackbody. A drawing of this lamp is shown in figure 8. This lamp is operated at a single current (7.7788 A dc) to produce a spectral

radiance about eight times higher than that of the gold-point blackbody at 655.3 nm (a radiance

temperature of about 1530 K). This lamp is stable to better than 0.1 °C over lOOh when

operated under these single-level conditions. A graph of the calibration history of the working

standard from August 1989 to February 1996 is shown in figure 9.

3.2.4 Variable-temperature blackbody

The NIST uses a commercial variable-temperature blackbody (VTBB) for its radiance

temperature transfer standard (See fig. 10). This VTBB was manufactured by Thermogage Inc.

in Frostburg, MD and was supplied with the Type II dual blackbody assembly (2.54 cm or 1 in

ID cavity), the 48 kW power supply, a control program, the model 7000-1 (4 range) optical

pyrometer, and a digital temperature computer control module. Modifications requested by the

NIST include the addition of the water-cooled semi-cylindrical mirrors, and enlarging the

extension tube opening to accommodate measurements with the NIST PEP.

The VTBB is operated between 700 °C and 2700 °C. The ranges, which are selected by

placing different size apertures on the optical control pyrometer, are the low range (700 °C to 1300 °C), the medium range (1300 °C to 1800 °C), the high range (1800 °C to 2500 °C), and the

extra high range (2500 °C to 2700 °C). The electrodes are water-cooled by using a 13 °C (55 °F)

chilled water source. Before the blackbody is turned on, argon gas displaces the air in the cavity.

When the VTBB cavity is operating, the argon exits from both the front and back extension

tubes.

The variable-temperature blackbody control system regulates the blackbody temperature

to within ±0.1 °C (see fig. 1 1). The NIST measures the uniformity of the center partition of the

Thermogage heater elements, and uses those with a spatial uniformity of better than ± 0.2 °C at 2000 °C over an area of 10 mm diameter (see fig. 12). The blackbody heats up to the operating

point in less than 30 min and responds quickly to temperature changes (see fig. 13). The day-today stability of the blackbody is better than ± 0.3 °C, and the 6-month stability is within ± 2 °C.

The VTBB operates between 800 °C and 2700 °C with an estimated emissivity of 0.99

from analytical modeling. The temperature distribution within the VTBB cavity is less than

50 °C. The blackbody cavity is composed of a single piece of graphite, which is specially

tapered for achieving high temperature uniformity. This graphite tube is cylindrically hollow on

both ends to form two 2.54 cm diameter cavities with a common partition in the center. One

cavity is used for temperature control, and the other cavity is the blackbody source.

15
16
Cylindrical sections with finer details

1 Quartz glass 2 Grafoil 3 Felt 4 Graphite heater element

5 Water cooling lines

6 Argon line 7 Control Pyrometer

8 Endcap

9 Extension /

Tube dUmeler ii 2.M

All dimensions in centimeters. 14.45-

•30.16-

Figure 10. Schematic of variable-temperature blackbody.

17
PS

<h:>

PTC TS

VTBB

4->

SD

ASA CW

LEGEND

ASA Argon Supply and Alarm CW 55 °C Chilled Water/Cold Water Switch PC Personal Computer

PS Power Supply PTC PID Temperature Controller SD Silicon Detector

TS Thermal Stabilizer VTBB Variable Temperature Blackbody

Figure 11. Variable-temperature blackbody control system.

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Horizontal distance from center (mm)

Temperature

difference (°C)

0 to -0.2 to 0.4 to 0.6 to 0.8 to

1 to

0.2

0

0.2

-0.4 0.6

0.8

Figure 12. Spatial scan of the variable-temperature blackbody at 2000 °C. The

temperature differences are from the center position (0,0).

18
Figure 13. Variable temperature blackbody control. After decreasing the set point by 100 °C, the blackbody

stabilizes in less than 10 min.

3.3 NIST photoelectric pyrometer

3.3.1 Measurement system

The PEP is a NIST designed transfer radiometer, which uses refractive optics to image

the source onto the detector. The schematic of the NIST PEP is shown in figure 14. A drawing

of the measurement system is shown in figure 15. The measurement system is completely

automated and controlled by a personal computer, while the laboratory environment is monitored

by temperature and relative humidity sensors. Lamps and blackbodies are positioned onto the

optical axis of the PEP using a closed-loop motor controller system that allows positioning to within 0.01 mm. The components of the pyrometer are discussed in the next three sections

followed by a discussion of the method used to characterize the system in the last three sections.

19
20
TC

PMT

WSL 1 VTBB

0 0 0 |e U e

GPL TL 1 1 TL M TL

GPBB

^ Source Table

LEGEND

AMP Amplifier PS Power Supply

DVM Digital Voltmeter RS Room Humidity Sensor EM Environmental Monitor TC Thermoelectric Cooler GPBB Gold-point Blackbody TL Test Lamp

GPL Gold-point Lamp TS Temperature Sensor PC Personal Computer VTBB Variable Temperature Blackbody PMT Photomultiplier Tube WSL Working Standard Lamp

Figure 15. NIST radiance temperature laboratory measurement system.

3.3.2 Optical system

The first element is the objective lens (OL) which is a 5.8 cm diameter bi-convex lens

with a focal length of 32 cm. The source is placed at twice the focal length from the lens and is imaged with unit magnification onto the field stop (FS), which is located at the back radius of

curvature. The dimensions of the rectangular field stop are 0.6 mm wide by 0.8 mm high. The

field stop defines the size and shape of the calibration target area. The next element is the

collimating lens (CL), which is a 2.45 cm diameter bi-convex lens with a focal length of

12.94 cm. The field stop is placed at the front focal point of this lens with the result being a collimated beam with a diameter of approximately 1.2 cm. Next the aperture stop (AS) reduces

the beam diameter to 1 cm. The beam continues through two interference filters (Fl & F2)

through a plano-concave diverging lens that spreads the radiant flux over the photomultiplier

tube cathode. The beam completely covers the surface of the cathode.

In all cases, the source overfills the objective lens and the aperture stop that corresponds

to a system with an /-number of 13. The solid angle (4.67 x 10"3 sr) used is a cone having a half

angle of 0.0772 rad (4.4°), the apex of which is at the center of the field stop.

To align sources, the field stop is removed, and the alignment prism (AP) is placed in the

21
path behind the field stop mount. The operator views the lamp filament or blackbody aperture

and moves the filament or aperture to the target area viewed by the PEP.

3.3.3 Interference filters

The PEP uses two interference filters centered on 655.3 nm to produce a very narrow

spectral bandwidth filter pack with transmitances in the wings six orders of magnitude lower than

the peak. The first filter is a three-cavity type, and the second is a four-cavity type. Both are 5.08 cm diameter filters made from polished optical quality glass and are coated with a metal

film. The regular spectral transmittances of the filters (see fig. 16) were measured from 400 nm

to 1000 nm in 0.2 nm steps (with a relative expanded uncertainty of 0.3 % at 655 nm) using the

NIST Transfer Spectrophotometer for Regular Transmittance described in reference [13]. The

expanded uncertainty of the wavelength calibration of the spectrometer used to make these

measurements was 0.5 nm at 655 nm. The first and second filters have spectral bandwidths of

1 nm and 10 nm, respectively. The central wavelength of the filters measured in series was

determined to be 654.9 nm with a bandwidth of 2.4 nm when using transmittance data around the

peak from 644 nm to 667 nm. For the full spectral range, the measured central wavelength was

836.6 nm with a bandwidth of 9.4 nm. The central wavelength Ac was determined from the

following equation for determining the effective wavelength,

50

640 645 650 655 660 665 670

Wavelength (nm)

Figure 16. NIST photoelectric pyrometer filter transmittances. The wavelength of the pyrometer is selected by using a 1 nm and a 10 nm spectral bandwidth (SBW) filter.

22
j A • ta

• dA

K= ~[ 7T- (17)

J TA

• dA

By approximating the integral with finite sums over equal wavelength bandwidths dA, Ac is found

to be

800

Q _

-

' = 400 . 1GX

goo Uo;

/ = 400

where the value of i indicates the wavelength in nm. The spectral bandwidth AAs was determined

from the following integral relationship,

j* Tx dX

AAS = i . (19)

^"peak

When the integral is converted into finite sums, the SBW becomes

800

AAS = ^ . (20)

^peak

3.3.4 Detectors

The PEP uses an 11 -stage photomultiplier tube with a quartz window and an extended

S-20 spectral response to measure spectral radiances. The detector is housed in a thermoelectrically cooled (-25 °C) chamber. The anode current is amplified and converted to a

0.1 V to 10 V signal by a programmable dc current amplifier and measured using a high accuracy

digital voltmeter, capable of integration times ranging from 0.2 s to several minutes.

The signals for the test source and the WS lamp can vary by as much as a factor of 1 100.

Because several amplifier gain settings are required to cover this dynamic range, all signals are normalized to the 108 V/A range. The amplifier normalization factors C\ are determined by

measuring the values of the four amplifier feedback resistors. Electrical currents / in the range

from 1 nA to 1000 nA are supplied to the current amplifier, and the output voltages V are measured using a digital voltmeter. The resistances R, determined using Ohm's law, V = I • R,

are R7 , R8 , R9, and Rio, for the (10

7

, 10

8

, 10

9

, and 10

10

) V/A ranges, respectively. The

23
normalization factors for each range are shown in table 3.

Table 3. Current amplifier normalization factors

Range [V/A] Normalization factor

10

7 Ca,R7 = Rg/R? = 9.9776

10

8 Ca,r8 = Rg/Rg = 1 10

9 Ca,R9 = R8/R9 = 9.9858 x 10"2

10

10 Ca.rio = Rs/Rio = 9.9846 x 10"3

3.3.5 Linearity of response

The degree of linearity of the PEP response is determined with a NIST designed

automated beam conjoiner [14]. A beam from a constant source is split into two branches,

whose fluxes are independently attenuated or blocked before recombination and further

attenuation. The flux contribution from both branches is equal to the sum of the fluxes from

each branch when measured separately (additivity). The device provides 100 levels of flux

ranging over a factor of about 500. The levels are presented in random order to avoid systematic

errors, and are interspersed with 25 zero flux levels. A personal computer controls the

attenuating filters and records the filter positions and radiometer signals. The data is leastsquares fitted to a polynomial response function to determine a correction factor (CO by which

the radiometer output signal must be multiplied to obtain a quantity proportional to radiant flux.

The correction factor is given by

CL = flux / signal = (A0 + A, • S + A2 S

2

) I S , (21)

where Aq, A\, and A2 are the coefficients found from the least squares approximation and S is the

signal as defined in eq (1). The current values for the coefficients are listed in table 4. The

magnitude of linearity correction factors is graphically shown in figure 17. The measured instrument response is linear to within ± 0.2 % for a range of

photomultiplier anode currents from 0. 1 nA to 500 nA. For currents much less than 0. 1 nA, the

signal is limited by noise. In order to ensure linearity of response, the current is restricted to a maximum of 500 nA by selection of the appropriate photomultiplier tube voltage. Typical

default hardware settings used by the calibration program are listed in table 5.

24
Table 4. Detector system correction factors and linearity coefficients

Gain

[V/A]

Ao

[V]

A,

A2 [V 1 ]

10

7 0.9987 for

500 nA

0.9973 for

1000 nA

-2.1274 x 10"8

1 -2 6687 x 10^

10

8 0.9998 for

50 nA

0.9996 for

100 nA

-2.1308 x 10"6

1 -3.8995 x 10"5

10

9 1.0002 for

5nA

1.0003 for

10 nA

-8.9698 x 10'9

1 -3.1787 x 10"5

1.0020

1.0015 1

1.0010 g 1 .0005 JOc 1.0000 g

o

Q>

i_i—O

0.9995

0.9990

& 0.9985

<a

03c

0.9980

0.9975

0.9970

Current amplifier ranges

x107 O 108 A 109

A A A A A A A A A A A

01 23456789 10 Signal (V)

Figure 17. The linearity correction factors for the PEP.

25
Ill o I El

Osm

00

tN©

SOSO

SO

00

in

inm<N

<*soorn

so

oo

OsOs©©

so

00

OS

Os©©

SO

r-t>Os

SO

OS

ao a u .2u

©

so

so

SO

00

>n

Csl r-

<n

tsCO

On

<N

SO 3 s

OS pi so

Os

SO

Os

X

in

©XmO

X

r~- 00

00

CO

X

«*o

p"

f9 o X

X

00©SO

X

rsO

>n©

X

r»00

Os

X

Oso © 53

on S IT] >n

min©

in

r->n

iri

IT) ©

mqinr-m o « °u

r-oo

Os

Os

Os©©'

Os

Ov

OS©©'

©©©' o©©

SO

r~

rOs

SO

r~

OSOs

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OS©

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00moo

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a. . . E U 4) o H 1—1

©

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Os

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26
3.3.6 Wavelength calibration

The mean effective wavelength of the PEP is calculated for temperature from 800 °C to 3000 °C by measuring its relative spectral response in the NIST Visible/Near Infrared Spectral

Comparator Facility [15]. The collimating lens, aperture stop, optics enclosure, and PMT system

of the PEP were set up in the Spectral Comparator Facility and the relative spectral response was

measured while maintaining the same system geometry as in the RTCL. The PEP was measured

from 400 nm to 900 nm in 5 nm steps and from 630 nm to 670 nm in 0.2 nm steps. The relative

spectral response was calculated from the following equation,

SpEP (jj

S«a (X)

'w GPEP (23)

where /?pep(A)is the relative spectral response of the PEP in [AAV] as defined in eq (2), S?e?(X) is the signal from the PEP in [V], Sm\(X) is the signal from the monitor detector simultaneous with

Spep(X), Sw(Jl) is the signal from the detector working standard (DWS), Sm2(X) is the signal from

the monitor detector simultaneous with Sw(X), Rw(^) is the absolute spectral response of the

DWS, Gw is the calibrated amplifier gain for the DWS in [V/A], and GPEp is the calibrated

amplifier gain for the PEP. The PEP results are relative spectral responses because the

measurement was performed in the overfill mode that resulted in a slightly different spot size.

From eq (18), the CW was determined to be 655.0 nm and the SBW was calculated to be 5.0 nm

from eq (20) for data over the 400 nm to 900 nm range. The CW was 655.3 nm with a SBW of

4.2 nm for the 630 nm to 670 nm data. Relative to the peak value, the measured relative spectral

responsivity values decrease to about 10"4 at 5 nm from the central wavelength and to about 10"6

at 50 nm as illustrated in figure 18. Spectral radiance as defined in eq (4) is a function of a single

wavelength, X. However, the PEP has a finite bandwidth, and the PEP measures radiance as defined by an integral form of the Wien equation,

900 C] Rk dX, (24)

400 X

5 exp(c2 l(X T))

which could be used in the ITS-90 definition of eq (14). In the RTCL, the single wavelength

Xj T used in eq (4) is be defined as follows,

(\ 1 ^

27
where "kj

Ti is the mean effective wavelength, L\ is the radiance of the test lamp at temperature

T\, and hi is the radiance of the WS at temperature T2 . All of the temperature measurements are performed for a mean effective wavelength of

655.3 nm, and these corrections are calculated for the VTBB with an emissivity of 0.99. The

spectral radiance LxiX, £a, T) of the blackbody is defined by eq (5) to be a function of the

wavelength, spectral emissivity, and the temperature, while the temperature T{X, Lx, £\) is defined by eq (6) to be a function of the wavelength, spectral emissivity, and the spectral

radiance. The following steps are performed to calculate the corrections at 900 nm for

T0 = 1073 K.

=> Calculate Lq= 1.2856 W-cm~3 -sr"', where X = 655.3 nm, ex = l,andr=7b

=> Calculate T\ = 1073.53 K, where A = 655.3 nm, ex = 0.99, and L\ = L0 => Calculate U = 68.31 W cm"

3 sf\ where A = 900 nm, ex = 0.99, and T=TX => Calculate T2 = 1072.80 K, where X = 900 nm, Sx= 1, and Lx = U

The corrections T2

- To that are added to the radiance temperature at 655.3 nm to determine the

radiance temperatures at 900 nm and 1000 nm are given in table 6. These corrections are equivalent to a spectral radiance correction of -0.27 % at 900 nm and -0.34 % at 1000 nm.

400 450 500 550 600 650 700 750 800 850 900

Wavelength (nm)

Figure 18. Relative spectral response of the NIST photoelectric pyrometer.

28
Table 6. Corrections (°C) to the radiance temperature at 900 nm and at 1000 nm

jjidCKDOQy lemperdiure ^ Q00 yyjvj nminn 1 nnn n m

800 -0.20 -0.27

1100 -0.32 -0.45

1500 -0.53 -0.75

1900 -0.80 -1.13

2300 -1.12 -1.58

3000 -1.82 -2.55

3.3.7 Size of source effect

Measurements are performed to determine how much of the measured flux is from

sources other than the target. This additional flux from outside the target area is scattered into

the measured beam by the optical system. The measurement is performed to determine the size

of source effect or the sensitivity of the PEP when viewing a 0.6 mm wide by 0.8 mm high target area on sources of various sizes. The magnitude of the size of source correction is determined by

measuring the spectral radiance of a large uniform diffuse source with various apertures in front

of the source. The large uniform diffuse source designed at NIST is used to measure the source of source effect. A 1 kW frosted quartz-halogen lamp is placed in a 20 cm by 23 cm by 20 cm

vented housing. A lens focuses the lamp onto an opening in the housing that is covered by a

diffuser. The apertures are on an aperture slide for quick positioning and reproducibility. The

aperture sizes measured are a 1.4 mm by 25.4 mm slit, a 3 mm by 25.4 mm slit, a 15 mm

diameter hole, and 25.4 mm diameter hole which approximate the sizes of the WS filament, the

TL filament, the Au blackbody opening, and the BB opening. The ratio r\ is the measurement of

the ratio of the WS to the AuBB in eq (9). The size of source correction is calculated from the

ratio of the measurements of the 15 mm diameter hole to the 1.4 mm by 25.4 mm slit. The

spectral radiance correction was 0.09 %, which corresponds to a correction factor of 1 .0009

± 0.0006 and a temperature correction of 0.10 °C. A negligible difference was observed for the

comparison of the measurements of the 1.4 mm by 25.4 mm slit and the 3 mm by 25.4 mm slit; therefore, the correction factor for ratio ri is 1 . The size of source correction for ratios and r$

is -0.13 % which corresponds to a correction factor of 0.9987 ± 0.0002. The correction was

calculated from the ratio of the measurements of the 1.4 mm by 25.4 mm slit to the 25.4 mm

diameter hole. The magnitude of the temperature correction varies from -0.07 °C at 800 °C to -0.52 °C at 2700 °C. The size of source corrections are shown in figure 19. Because of flux

contributions from outside the target area, the larger area BB results in a higher temperature. A

negative correction is added to subtract the additional flux.

29
0.2

c

o

O

0)

i_

i_o

o

o

o

(0

0)N

(7)

0.1

0.0500

-0.1

-0.2

O -0.3

-0.4

-0.5

-0.6

1255 °C

a Vtbb/SL20

• SL20/AuBB

H 1 1 1 1 h H h H h H H h 1000 1500 2000 2500 3000

Temperature (°C)

Figure 19. The size of source corrections for the variable temperature blackbody to the working

standard lamp comparison and the working standard lamp to the gold-point blackbody.

3.4 Radiance temperature scale uncertainties

From the laws of statistical theory, when the covariances of the independent variables are assumed to be negligible, the propagation of standard uncertainty u{y) for a variable y,

(26)

can be defined in terms of the following sum,

u(y) = ( 0

7T7 dx:

1/2

(27)

where u(xf) are the standard uncertainties. The uncertainty in the WS lamp spectral radiance,

30
U0 v-^WS ) dLws

+

dnu{nk )

u(c2 )

OLws _Y (dL

+

1=1

dX

dL

u(X) +

ws dT

\

nl/2

Ail

ws

"(*,)

u(TAu )

(28)

can be calculated by the root sum of squares (RSS) of the products of partial derivatives with

their respective uncertainties. This uncertainty «o(£ws) can be derived directly from the

measurement equation in eq (16) by using the propagation of standard uncertainty relationship in

eq (27). The partial derivatives are those of the spectral radiance with respect to the independent

variables in eq (16) and are listed in eqs (29) through (33). The eleven variables in the

summation of eq (28) are the following variables: eAu, c lL, n, CA,ws, CL,ws, Cs.ws, Gws, Ca,au , Cl,au, Cs.Au, or Gau- Since all of the measurements in the RTCL are based on the WS lamp, the

uncertainty analysis of each calibration service (tungsten ribbon filament lamps, disappearing

filament optical pyrometers, infrared thermometers) will be completed in Sections 4, 5, and 6

using the uncertainty in wo(Lws)-

The measurement equation for the radiance temperature scale from the gold-point

blackbody to the WS lamp can be represented by eq (16). The partial derivatives of the WS

spectral radiance in eq (16) with respect to the variables, ni, A, Tau, and ci, are

X T,Au

r exp

X T,

exp

Au - 2

XT - 1 Au

(29)

dX X X T,Au

exp

X TAn

exp

X T, - 1 Au

(30)

37\,

Lws

Au X TAu

exp

X T,Au

, and (31)

exp

v "a • 4 • TAu - 1

31
dAys _ Ays

3c,

exp

c2 nK X- TAu exp

(32) - 1

The expression in eq (28),

3jc

Avs

(33)

represents the partial derivatives of Lws with respect to x, where x is one of the eleven variables

in eq (28).

Table 7 details typical values of the variables in eq (16), while table 8 summarizes the

uncertainties in eq (28). The uncertainty u(TAu) in table 8 is derived from the NIST radiometric

determination of the freezing point of gold [16]. The combined uncertainty m(Lws) in the spectral

radiance of the WS lamp can then be calculated by calculating the RSS from the following

expression,

"(Are) =

Avs

^ u0 (Lws )

''

Avs + ^w(LTC)^

2 h(DMM)

Avs +Avs

+

( m(LD) ^

Avs

-il/2

(34)

where «(DMM) is the digital multimeter uncertainty, w(LTC) is the lamp current uncertainty, and

m(LD) is the lamp drift uncertainty. From tables 7 and 8, a typical relative expanded uncertainty

in the WS spectral radiance is equal to (2.870 W m"

2 um

"

1 -sr"1 )/(569.9 W-m"2 -um "^sr"

1 ), or 0.50 %. The final value of the WS spectral radiance will be utilized in Sections 4 through 6 to continue the uncertainty analyses for each type of calibration service.

3.5 Quality control

The Radiance Temperature Measurements Calibration Service ensures quality

measurements through quality system implementation, internal quality control procedures,

periodic audits, and interlaboratory comparisons. The Quality System Manual for the Radiance

Temperature Measurements Calibration Service is based on the ANSIZNCSL Z540- 1-1994

standard [17] and the ISO/IEC Guide 25 [18]. The Quality System Manual is organized into

three sections that form a pyramidal shape. The top section is the Optical Technology Division

Quality System Policies, the middle section contains the Division Procedures that uniformly

apply to all the calibration services, and the bottom section is the Calibration Service Procedures

for each calibration service. Additional information on the Divisions Quality System can be

found in reference [19].

32
Table 7. Typical values of WS lamp variables and parameters

Variable Symbol Value

Refractive index nx 1.00028

Wavelength X 655.3 nm

Freezing temperature of gold 1 An 1337.33 K

Second radiation constant Cl 14387.69 (im-K

Emissivity of Au 0.9999

First radiation constant Cm 1 191 x 10

8 W um4 -m"

2

i 1 y 1 X W T T 1 11 111 Rntin nf sicrnal tn An c i crn si 1 1 1 7 764

WS amnlifier calibration correction 1 WS linearity correction Cl,ws 1 WS size of source correction Cs.ws 1.0009

WS amplifier gain Gws 1 x 10

8 V A"1 Au amplifier calibration correction Ca,Au 1 Au linearity correction Cl,Au 1 Au size of source correction Cs.Au 1 Au amplifier gain Gau 1 x 10

8 V A"1 WS spectral radiance 569.9 W-rnVrn'-sr-'

33
Table 8. Uncertainty budget for the NIST WS lamp spectral radiance realization

Expanded

U Ill/CI lallliy L.U1I1JJLM1CI11 O y II1UU1 Uncertainty (/: = 2)

Type A Type B

Refractive index u(nx) 0.00002

Wavelength u(X) 0.2 nm

Freezing temperature of gold W(Xau) 0.23 K

Second radiation constant u(c2 ) 0.24 |nm-K

Emissivity of Au u(£au) 0.0002

First radiation constant u(cm) 440 W-Lim4 -m"

2

1 I V f T LAI 11 111 Ratio of WS signal to Au signal u(r\) 0.006

WS amplifier calibration correction m(Ca,ws) 0.0001

WS linearity correction w(Cl,ws) 0.001

WS size of source correction w(Cs,ws) 0.0006

WS amplifier gain 0 VA"1

r\U ampilliei CallUlallUll HJIICC-11UI1 M^A.AuJ U.UUU 1 Au linearity correction «(Cl,Au) 0.001

au size or source correciion til C„ .

"\ u.uuuz Au amplifier gain m(Gau) 0 VA"1 WS lamp spectral radiance wo(^ws) 2.754 W-nfVm^sr"1

Digital voltmeter w(DMM) 0.000 Wm^jLim^sf1 WS current w(LTC) 0.570 Wm^iim'sr 1 WS drift m(LD) 0.570 W/m2/|Lim/sr

NIST WS lamp spectral radiance 2.870 W m

2 vim

1 sr1

NIST WS lamp temperature u(Tws) 0.536 K

34
The calibrations resulting from the processes described in this document are derived in principle from a complete realization of the radiance temperature scale, and therefore are not

dependent upon the maintenance of in-house standards. In practice, the realization often omits

the GPBB comparison and relies upon the spectral radiance that is maintained on the stable

working standard lamp. The calibration history of the lamp compared to the GPBB is monitored

to confirm the stability of the lamp (see fig. 9). The working standard lamp is compared to the

gold point blackbody at least twice a year. Lamp and radiation thermometer check standards are periodically measured to ensure the accuracy of the measurements. The calibration history of the

ribbon filament lamp check standards (Serial numbers P51 and P74) are shown in figure 20,

while the calibration history of the radiation thermometer check standard (Minolta Cyclops 52) is shown in figure 2 1 . The calibration process is further monitored by using control limits in the

data acquisition and data reduction programs. A check-list is used to track the status of the test unit throughout the calibration process. A calibration summary sheet is created for each

calibrated item to record customer information, measurements performed, test unit information,

environmental conditions, filenames, and computer programs used for data acquisition and

reduction. The calibration report is carefully reviewed by a party who was not involved in

producing the values.

Audits are performed annually by the Division's quality control team. This calibration

service participates in bilateral and multilateral laboratory comparisons of radiance temperature

with various national laboratories usually involving guest scientists [20,21].

Figure 20. Calibration history of the ribbon filament lamp check standards.

35
^

2

Oo ? 1 oO

0

sre Q K -1

-2

500

o Apr-92

a Sep-94

x Jun-95

Oct-96

+ Jul-97

1000 1500 2000

Temperature (°C)

2500

Figure 21. Calibration history of the radiation thermometer check standard (Minolta Cyclops 52).

36
4. Tungsten Ribbon Filament Lamp Calibrations

4.1 Lamp preparation

Tungsten ribbon filament lamps are calibrated by NIST for the temperature range 800 °C

to 2300 °C in terms of the 1990 NIST Radiance Temperature Scale by spectral comparison to a standard temperature lamp calibrated at 655.3 nm. New lamps are inspected for filament

continuity, envelope and window clarity, and filament flatness and centering. A digital

multimeter is used to check the filament continuity. The envelope or window is checked for

defects and striations in the optical path. The filament is checked to determine that it is flat, parallel to the envelope walls, and within 2 mm of being centered in the envelope or window.

The lamps are cleaned with water and laboratory glassware detergent.

Test lamps (TL) are operated base down on direct current with the center contact (longer

filament support for a bipost base lamp) at the positive potential. The test lamps are tested for air

leaks by turning the lamp on, then off, and then on again after 15 min. If air has leaked into the

lamp envelope because of bad or broken seals, then the lamp will fail when it is turned on. Lamps that pass the leak test are annealed to improve lamp stability. New gas lamps are annealed at a radiance temperature of 2350 °C at 655.3 nm for 2 h on direct current and vacuum

lamps are annealed at 1450 °C for about 14 h. The gas lamps are aged for an additional 50 h at 2300 °C.

The lamp orientation chosen for the calibration of a new lamp minimizes the variation in

lamp output while maintaining the optical axis of the measuring instrument approximately

normal to the lamp filament. This orientation is determined with the lamp operating at approximately 1700 °C for a gas lamp, or 1200 °C for a vacuum lamp. An arrow is etched onto

the rear surface of the lamp envelope to allow reproducible alignment of this orientation. The

alignment is performed with the lamp operating base down, the filament vertical, and the optical

axis of the PEP passing through the lamp envelope and intersecting the center of the filament at the height of the notch. The sides of the target area, area 0.6 mm wide by 0.8 mm high, are approximately parallel to the sides of the lamp filament. The center of the target area is located

at the intersection of two orthogonal lines on the filament surface. One line bisects the filament

lengthwise, and the other passes through the point centered at the mouth of the notch. The lamp

is positioned so that the etched arrow on the lamp envelope is to the rear, as viewed from the

PEP. The center of the target area is viewed along the horizontal optical axis of the PEP. A

plumb line is used to make the notch side of the filament vertical. The image of the lamp

filament is focused onto the field stop of the PEP to within ±2.5 mm. The lamp is then

successively rotated about the horizontal and vertical centerlines through the target area until the

tip of the arrowhead is centered at the mouth of the notch.

4.2 Lamp calibration

The values of radiance temperature apply when the lamp has been aligned to a specified

orientation while operating at a designated radiance temperature and after the lamp has reached

thermal stability at each specified operating current. The WS and TL are aligned as described in

Section 4.1 at one temperature. At all other temperatures, the TL is translated vertically and/or

horizontally so that the target area viewed by the PEP is always centered on the lamp filament at the height of the notch. No additional rotational alignments are performed

37
The initial lamp current that corresponds to 1700 °C is selected from previous data for the

lamp type. The TL is turned on and set to approximately 1700 °C and aligned after 30 min. The

spectral radiance ratio of the TL to the WS, ri, is calculated, the WS signal, Sws2, is measured,

and the TL signal, Stl, tnat corresponds tol700 °C is calculated. The lamp current is adjusted

until the measured signal is equal to Stl- After waiting 10 min, the final alignment of the TL and

the WS is performed and the TL is spectrally compared to the WS to determine its radiance

temperature. The spectral radiance ratio of the TL to the WS is measured three times by

alternately translating the WS and the TL to the PEP. If the percent standard deviation of the

ratio is less then the control limit, then the next calibration point is measured; otherwise, the

point is repeated. The control limits are equal to the relative standard uncertainty {k = 1 ) of the

ratio and were determined from previous calibration data. The control limits are the expected

uncertainties for the spectral radiance ratio measurement. Next, the TL is aligned and measured

at 2300 °C after waiting 20 min. The additional calibration temperatures are aligned and

measured in decreasing order after waiting 10 min. A typical calibration interval is 100 °C. The

following temperatures are repeated at the previously determined lamp currents to estimate the

lamps stability: 1700 °C, 2300 °C, 1900 °C, 1500 °C, 1 100 °C, and 800 °C. The following data

is stored in a computer file: nominal temperature, measured temperature, lamp current, and

spectral radiance ratio. See the "Ribbon Filament Lamp Calibration Procedure" in Appendix D

for a more details on lamp calibrations in the RTLC.

4.3 Lamp data analysis

The repeated calibration temperatures are averaged and the standard error of the mean is calculated and compared to the absolute control limits. These results are used to determine the

expanded uncertainties listed in the calibration report.

Calibration data is reported at the nominal temperatures 800 °C, 900 °C, 1000 °C, ... 2300 °C. One method to determine the nominal temperatures is to measure it directly. Through

an iterative process, the TL is repeatedly measured and the lamp current is adjusted until the

nominal temperature is actually measured. However, the RTCL calculates the lamp current that

corresponds to the nominal temperature from measurements of the measured temperature (rm) near the nominal temperature (rn). For a small AT, where AT - Tn

- Tm, the small change in lamp current is approximated by

the slope of the tangent at T and given by

dI(T) AI

r — I(T + AT) - I(T) .... = hm —— = lim — • pjj

di Ar->o AT Ar->o AT

This limit simplifies to a working equation of the form

I(T + AT) = I(T) + AT , (36)

dT

where I(T) is the measured lamp current /m at Tm and I(T + AT) is the measured lamp current 7( The derivative dl/dT can be approximated by AI/AT, which can be modeled as

38
AT %

a> (37)

The coefficients a, are calculated from a least squares fit of two other parameters, Tmem and

AI/AT. The first parameter is defined by

Tmean T + T

(38)

and the slope of the line between the calibration points Pk and Pk+ \ in figure 22 is given by

A/ ^m,* — Im,k + l (39)

Figure 22 shows the shape of the curve for Tm versus /m. AI/AT(Tmean) is fit to a fifth degree

polynomial giving the coefficients q. Figure 23 shows the shape of the curve with of Tmean and

AI/AT used to calculate the coefficients a7

. From eq (36), the corrected lamp current is

Figure 22. Calculation of Icori from T^an and A//Ar.

39
determined to be

/corr = /m + (r„ " Tm) (40)

3

Figure 23. Graph of 7mean and M/AT.

A least squares fit of the entire calibration data sets finds the best curve for the data set but not

necessarily for each data point. This method ensures that the direction of the correction is right

and has been verified by comparison to the iterative method. Sample data can be found in the

"Ribbon Filament Lamp Data Reduction Procedure" in Appendix D.

4.4 Lamp calibration uncertainty

To calibrate test lamps (TL), the ratio {ri) of the spectral radiance of the WS lamp to that

of the TL,

r2 =

Lx(Tjl) = Jk- , (41)

(^WS2 ) ^WS2

40
is first measured. Taking into account the correction factors for the signals, the overall

measurement equation for the 1990 NIST Scale of Radiance Temperature for calibration of the

TL temperature is

T =

X In 1 +

'A,TL (CA

• CL• Cs G)ws

^WS2 r2 (Ca CL Cs G)TL

(42)

In a manner similar to eq (28), the uncertainty in the spectral radiance of the WS can be

represented by the RSS of products of partial derivatives,

W0 (-^TL )

r drTL , !\ far,

dn.

u(nx) +

TL dX

u(X) +

TL u(c2 )

12 ( ?>T ^

nl/2

(43)

where x\ is one of the variables: £tl, c[L, LWs, r2, Ca.ws, Cl,ws, Cs.ws, Gws, Ca.tl, Cl.tl, Cs,tl, or Gtl- The partial derivatives of 7tl with respect to nx, X, and c2 are

ar,TL TL

(CA • CL

• Q • G)WS

' A,TL C 1Z. (CA ' CL

' CS' G)TL "I

* ^WS2 A • 7; exp

TL l A

" ^ ' ^TL ;

(44)

ar,TL aA

TTL "A.TLX

5 LWS2

(Ca " Cl ' Cs

• G)

(c, TL

nx X TTL exp

- 1

X ZTL

, and (45)

TL TL (46)

41
The partial derivatives of 7tl with respect to x are

TL TL

dx

A.TLA • Z/^yS2

OS.

(c,

"a * TL

Cs

• G).

exp

(47)

A • 7;TL

where x is one of the variables labeled xx in eq (43).

Typical values of the variables in eq (42) are shown in table 9, and the uncertainties of

eq (43) are displayed in table 10. The total expanded relative uncertainty m(7tl)/7tl in the TL

temperature has contributions from wo(Ttl) in eq (43), from the uncertainty m(TLC) in the TL

current, and from the uncertainty m(AL) in alignment. These contributions are shown in table 10

and are summed by the RSS technique as follows,

u{TT.)

TL

M0 (^TL )

TL + ^m(TLC) ^TL

r u(AL) ^

-11/2

TL (48)

From tables 9 and 10, a typical relative expanded uncertainty in the TL temperature realization is 1.10 K/1973.52 K, or about 0.059 %. For other nominal TL temperatures besides 1700 °C, the user is referred to table 2.

Table 9. Typical values of TL variables and parameters

Variable Symbol Value

Refractive index 1.00028

Wavelength A 655.3 nm

Second radiation constant C2 14387.69 nm-K

Emissivity of TL £tl 1 First radiation constant C\L 1.191 x 108 W-nm4-m"

2 WS spectral radiance Ly/S 569.9 Wm'2 M.m

1 sr1

Ratio of TL signal to WS signal ri 2.551

WS amplifier calibration correction Ca.ws 0.09986

WS linearity correction Cl,ws 1 WS size of source correction Csy/s 1 WS amplifier gain Gws 1 x 109 V A"

1 TL amplifier calibration correction Ca.tl 1 TL linearity correction Cl,tl 1 TL size of source correction Cs,TL 1 TL amplifier gain Gtl 1 x 10

8 V A"1 TL temperature 1973.52 K

42
Table 10. Uncertainty budget for the TL temperature calibration

Expanded

Uncertainty component Symbol Uncertainty (k = 2)

Type A Type B

Refractive index u(nx) 0.00002

Wavelength 0.2 nm

Second radiation constant u(ci) 0 24 um-K

Emissivity of TL u(Fti ^ 0.0002

First radiation constant uiCu ) 440 W-um4 m"2

1 r\J T T LV1 11 111 Z.yyo W-ITl \lu\ -ST Ratio of TL signal to WS signal u(r2 ) 0.0051

WS amplifier calibration correction w(Ca,ws) 0.00001

WS linearity correction w(Cl,ws) 0.001

WS size of source correction "(Cs.ws) 0.0002

WS amplifier gain w(Gws) 0 V-A"

1 TL amplifier calibration correction u(Cajl) 0.0001

TL linearity correction w(Cl,tl) 0.001

TL size of source correction w(Cs ,tl) 0.0002

TL amplifier gain w(Gtl) 0 V-A"

1 TL temperature «o(Ttl) 1.10 K

TL current w(TLC) 0.09 K

Alignment u(AL) 0.30 K

TL temperature calibration "(Ttl) 1.10 K

43
5. Disappearing filament optical pyrometer calibrations

5.1 Optical pyrometer preparation

Disappearing filament optical pyrometers (DFP) are calibrated from 800 °G to 4200 °C

by comparison to the VTBB. When the test unit arrives, the batteries are checked, the objective

lens and eyepiece are cleaned, and the eyepiece is focused onto the DFP lamp filament. The

lamp is checked to ensure that it is operating and that matching is possible. If an operating

manual is not on file, then one is requested from the customer because test pyrometers are operated according to the manufacturer's instructions unless other instructions are given. The

pyrometers and associated electronics are initialized according to manufacturer's specifications.

5.2 Optical pyrometer calibration

The DFP is aligned onto the geometric center of the VTBB opening. The DFP is measured at an appropriate distance from the front surface of the objective lens holder to the

blackbody cavity partition and is focussed on the center of the partition. After the VTBB is turned on, the pyrometer centering is checked and adjusted as necessary.

For the 800 °C to 2700 °C temperature range, the PEP is used to spectrally compare the

VTBB to the WS to determine the radiance temperature of the blackbody at each calibration

temperature. The VTBB and the WS are compared three times and the mean is used. Once the

temperature of the blackbody has been determined, the test DFP lamp filament is matched in

brightness to that of the blackbody, and the DFP lamp current is measured using a standard resistor

and a digital voltmeter. The matching is performed from bright to disappearance and from dark to disappearance twice and the mean of the four readings is used. The indicated temperature is recorded for pyrometers with either a temperature scale or a digital panel indicator. The output

voltage is measured for pyrometers with internal current measuring resistors. The DFP

measurements are not bracketed by VTBB measurements because the VTBB has been shown to be

stable to within ± 0. 1 °C during the time required to complete the measurements.

For temperatures above 2700 °C, the method used to extrapolate the calibration to 4200 °C

involves measuring temperatures below 2700 °C on two or more ranges. For a three-range DFP

with a low range (L) from 1 100 °C to 1700 °C, a medium range (M) from 1700 °C to 2800 °C, and

a high range (H) from 2900 °C to 4200 °C, the following measurements are performed. The DFP

lamp currents are measured for VTBB temperatures from 1 100 °C to 1700 °C on the L range, from

1600 °C to 2700 °C on the M range, and from 1700 °C to 2700 °C on the H range.

5.3 Optical pyrometer data analysis

The various data reduction methods used are determined by how the DFP indicates

temperature. In all cases, the data is sorted by range and averaged and the standard deviation is calculated. For DFPs with ranges below 2700 °C, the data is analyzed and the blackbody

temperature versus the scale or panel reading, output current, or output voltage is reported. The

pyrometer correction, blackbody temperature minus DFP reading, that is added to the pyrometer

reading is reported for scale and panel indicator DFPs.

For the three-range DFP case when temperatures are determined above 2700 °C, more

calculations are required before the data is reported. The current measurement averages are fit to

44
the curve I(T) = ao + a\T + a^T + ayT calculating a least squares approximation for each DFP

range. For the L range the blackbody temperatures are calculated at the nominal temperatures

1100°C, 1200 °C, 1700 °C and reported versus the pyrometer lamp currents. For the

M range, the blackbody temperatures are calculated at the nominal temperatures 1700 °C,

1800 °C, 2700 °C and reported versus the pyrometer lamp currents. The 2800 °C calibration

point is determined in two steps. The first step is to calculate AM , the "A" value [22] for the M

range, which is defined be the relationship,

A = - -±- = — 4n T , (44)

* APP * BB C2

where TAPP is the apparent temperature [K], rBB is the blackbody temperature [K], X is the filter transmittance, and A is the "A" value [K~ ]. From eq (44), it becomes apparent that In t must be

approximately equal to MX in order for A to be constant. Typically, the value of A is on the order

of 173X10"6 K"

1

. rBB , is determined during the M range measurements. TAPP is the temperature on

the L range that corresponds to the current measured on the M range which is determined through

iteration of the L range function I(t). The second step is to use the "A" value to calculate the

pyrometer lamp current that corresponds to the extrapolated blackbody temperature at 2800 °C.

Use eq (44) to calculate TAPP2 when TBm = 3073.15 K and A = AM. Next calculate the pyrometer

lamp current using the L range function /(?)• This procedure is repeated to determine the extrapolated blackbody temperatures for the H

range. The H range "A-value", AH , is determined where TAPP is the temperature on the L range

that corresponds to the current measured on the H range and TBB is the blackbody temperature

during the H range measurements. AH is then used to calculate the apparent temperature TAPP2 for

each extrapolated blackbody temperature from 2900 °C to 4200 °C. The pyrometer lamp

currents are calculated from the L range function I(t). The extrapolated blackbody temperatures

for the M and H ranges are reported versus the pyrometer lamp currents.

5.4 Optical pyrometer calibration uncertainty

To calibrate disappearing filament optical pyrometers (DFP), the ratio (r?) of the spectral

radiance of the WS lamp to that of the variable-temperature blackbody (BB),

Lx (Tbb ) _ ^BB

(45)

is first measured to determine the radiance temperature of the BB, T(A,La,bb), at each

disappearing filament optical pyrometer temperature by the equation,

T1 = BB A • In 1 +

A,BB ^ ' AvS3 ' h (^A " S ^ObB _

(46)

45
The uncertainty in the spectral radiance of the BB can be calculated by the RSS of products of

partial derivatives of eq (46) with their respective uncertainties as follows,

M0 \ BB ) —

ar,BB u(nx ) +

far,

12 ( r)T

v

-11/2

-52- • U(X)

dX

V far,BB

, ac2 «(c2 )

(47)

1=1

BB dx. u{xi )

where xj is one of the following variables: £Bb, c\L, r3, CA,ws, Cl,ws, Cs,ws, Gws, Ca>bb, Cl,bb,

Cs,bb, or Gbb- The partial derivatives of nx, X, and ci can be derived from eq (46) as

ar,BB dn.

BB

2

• £A,BB ' C\L

(^A ' ^)\VS

(CA

• CL Cs• G)BB -

S3 X • Z

exp

BB

v nx 4 • rBB

(48)

ar,BB aA

BB ^A.BB ' C1L

x

• X £ws3

(CA

' CL' Q ' G)

(CA • CL ' Q ' G)

«A • ^ • ^BB

exp

V «A

- 1 , and

A • r,BB

(49)

ar,BB BB (50)

The expression,

ar,BB a*

BB £A,BB " CIL nx X S3

(CA

• CL• Cs• G)ws ^)bb

nk" ^ " ^bb

exp

v «a • ^ • rBB y

(51)

46
represents the partial derivatives of TeB with respect to x, where x is one of the variables, £B b, C\l,

r-i, C\,ws> ^l,ws, Cs.ws, G\vs, Ca.bb, Cl,bb, ^s.bb, or ^bbA summary of the DFP variable values in eq (46) in table 1 1. Uncertainty values from

eq (47) are given in table 12. Table 12 also shows the standard uncertainties leading up to the

total standard uncertainty in the DFP temperature,

w(^bb )

BB

( U0 (^BB )

BB +

w(DMM)

BB

1/2

(52)

The uncertainty in the pyrometer temperature is related to the uncertainty in the variabletemperature blackbody temperature by the following relationship,

^(*DFP )

DFP

u\Tm ) + { n(BU) ^ + f m(PR)

1 BB ' DFP j +

1 DFP J

1/2

(53)

where w(BU) is the blackbody uniformity uncertainty and u(PR) is the pyrometer reading

uncertainty. The relative expanded uncertainty in the DFP temperature from tables 11 and 12 is 7.57 K/2579.07 K, or 0.29 %. The uncertainty values for other DFP temperatures are listed in

table 2.

Table 11. Typical values of DFP variables and parameters

Variable Symbol Value

Refractive index nx 1.00028

Wavelength X 655.3 nm

Second radiation constant 14387.69 fim-K

Emissivity of BB £bb 0.99

First radiation constant C\L 1.191 x 10

8 W uxn4 m

WS spectral radiance 569.9 W-m'Vm^sf

Ratio of BB signal to WS signal 3.445

WS amplifier calibration correction Ca,ws 0.09986

WS linearity correction Cl.ws 1 WS size of source correction Cs,ws 1 WS amplifier gain Gws 1 x 10

9 V A"1 BB amplifier calibration correction Ca.bb 9.978

BB linearity correction Cl,bb 0.9997

BB size of source correction Cs,BB 0.9987

BB amplifier gain Gbb 1 x 10

7 V A"1 BB temperature 7bb 2579.07 K

47
Table 12. Uncertainty budget for the DFP pyrometer temperature calibration

Expanded

Uncertainty factor Symbol Uncertainty (k = 2)

Type A Type B

lVvl 1 CWs Li V K/ 1 J lUvA 0 00002

w aveiengin U{A) u.z nm

oecona raaidiion constant U{C2) U.Z4 (xm-K

umissiviiy or r>r> w(£bb) u.uuuz

First radiation constant U(C\i) 440 W-pxn m

WS spectral radiance «(Lws) 2.998 W m \im -sr Ratio of BB signal to WS signal 0.00682

WS amplifier calibration correction w(Ca,ws) 0.00001

WS linearitv correction 0.001

WS size of source correction «(Cs,ws) 0.0002

WS amplifier gain w(Gws) 0 V-A"

1 BB amplifier calibration correction w(Ca,bb) 0.001

BB linearity correction w(Cl,bb) 0.001

BB size of source correction "(Cs.bb) 0.0002

BB amplifier gain w(Gbb) 0 VA"1

Digital voltmeter m(DMM) OK

BB temperature "(Xbb) 2.34 K

Blackbody uniformity k(BU) 0.20 K

DFP reading m(PR) 7.20 K

DFP temperature calibration w(Tdfp) 7.57 K

48
6. Infrared thermometer calibrations

6.1 Radiation pyrometer preparation

Radiation thermometers (RT) are measured for the temperature range from 800 °C to 2700 °C. The RTs are operated according to the manufacturer's operating instructions unless

special instructions are given. First, the lens, eyepiece, and filters are cleaned; then the

emissivity control is set to unity. The RT is aligned so that its optical axis, when viewing the

VTBB, coincides with the geometrical center of the blackbody.

6.2 Radiation pyrometer calibration

The VTBB is turned on and set to the highest temperature measured. After waiting

30 min, the PEP is used to determine the radiance temperature of the VTBB by spectrally

comparing it to the WS lamp at each calibration temperature from 2700 °C to 800 °C in 100 °C

steps. The measurements are repeated at 2300 °C, 1900 °C, 1500 °C, 1100°C, and 800 °C to determine the stability of the RT. The VTBB is compared to the WS three times, and the average

of the measurements is used. After the temperature of the VTBB is determined, three RT

measurements of the VTBB are made, and the output current, output voltage, or indicated

temperature is recorded. The spectral radiance temperatures of the VTBB used in the calibration are determined at wavelengths of 655.3 nm, 900 nm, and 1000 nm. For 100 °C temperature

changes, the VTBB is measured after waiting 5 min for the VTBB to stabilize.

6.3 Radiation pyrometer data analysis

For RTs with output currents or voltages, the nominal temperature, the VTBB

temperature, and the output current or voltage are reported in the test report. For RTs with

temperature indicators, the nominal temperature, the VTBB temperature, the temperature

indicated by the RT, and the RT correction are reported in the test report. The RT correction is equal to the VTBB temperature minus the RT indicated temperature.

6.4 Radiation pyrometer calibration uncertainty

To calibrate radiation thermometers (RT), the ratio (r^) of the spectral radiance of the WS

lamp to that of the variable-temperature blackbody (BB),

is first measured to determine the radiance temperature of the BB, T(A,La,bb), at each test temperature by the equation,

'A Cj^RT

)

_ *^RT (54)

(^A ' ^)\VS

(^a CL

' Cs g)bb

(55)

£ 1L nx

• X • In 1 +

S4

49
The uncertainty in the spectral radiance of the BB can be calculated by the RSS of the products

of the partial derivatives in eqs (57) through (60) with their respective uncertainties,

W0 (^~BB ) —

r *Tm . ^ farnn _Y far, u{nx ) +

BB

12 + 1 OX;

\

-|172

dX

u(X) +

\

2 BB

, 5c2 u(c2 )

(56)

where *j is one of the following variables: £RT, clL, r4, CA,ws, CL,ws, Cs ,ws, Gws, Ca.bb, Cl,bb,

Cs.bb, or Gbb- From eq (55), the partial derivatives of n%, A, and ci are

BB dn.BB

2 15 AVS4

WS

(CA CL Cs G)BB

• exp

BB nX

* ^ • ^BB

(57)

ar,BB aA

BB A

5

• S4

(c, ' ^S G)WS

(CA

• CL• Cs• G)BB

nX

• 4 • ^BB

• exp XT,BB J

, and (58)

ar,BB BB (59)

The expression,

ar,BB a*

BB ' A,RT C

1L

• A • LWS4

(CA

• CL. Cs. G)WS

(cA

• cL• cs• g)BB

nx & rBB exp

nx• h * ^bb ;

(60)

represents the partial derivatives of Tbb with respect to jc, where x is one of the variables, £rt, c\l,

50
f4, Ca.ws. Cl,ws5 Cs.ws. Gws, C\,bb, Cl,bb, Cs.bb, or GbbTable 13 shows the typical values of the variables in eq (55). The uncertainties of eq (56)

are displayed in table 14. Finally, the total expanded uncertainty shown in table 14 is

"(Tbb)

BB

( M0 (-^BB ) V (

+

BB

«(DMM)

-il/2

BB (61)

The uncertainty in the RT temperature is related to the uncertainty in the variable-temperature

blackbody temperature by the following relationship,

u(TRT )

RT

" <Tbb) 'm(BU)^

BB RT

( w(RTR) ^

RT

1/2

(62)

From tables 13 and 14, the relative expanded uncertainty in the 7Vr is 3.05 K/2579.07 K, or 0.12 %. For other RT temperatures, table 2 can be used to approximate the uncertainties.

Table 13. Typical values of RT variables and parameters

Variable Symbol Value

Refractive index n\ 1.00028

Wavelength X 655.3 nm

Second radiation constant Cl 14387.69 u.m-K

Emissivity of BB £bb 0.99

First radiation constant 1.191 x 10

8 W |um4 m"2 WS spectral radiance 569.9 W-rnVm^sr"1

Ratio of BB signal to WS signal 3.445

WS amplifier calibration correction Ca.ws 0.09986

WS linearity correction Cl,ws 1 WS size of source correction Cs.ws 1 WS amplifier gain 1 x 10

9 V-A"1 BB amplifier calibration correction C\,bb 9.978

BB linearity correction Cl,bb 0.9997

BB size of source correction Cs,BB 0.9987

BB amplifier gain Gbb 1 x 10

7 V-A"1 BB temperature Tbb 2579.07 K

51
Table 14. Uncertainty budget for the RT temperature calibration

Expanded

Uncertainty component Symbol Uncertainty (k = 2)

Type A Type B

Refractive index u(nx) 0.00002

Wavelength 0.2 nm

Second radiation constant u{c2) 0.24 |0,m K

Emissivity of BB "(£bb) 0.0002

First radiation constant u(c lL) 440 W-jxm4 -m"

2 WS snprtral raHiancp u( Ta\/q\ 9 QQR W.m'2 i.77o vv in .iim'Ur' ixiii M

Ratio of BB signal to WS signal u(r4 ) 0.00579

WS amplifier calibration correction m(Ca,ws) 0.00001

WS linearity correction w(Cl,ws) 0.001

WS size of source correction w(Cs,ws) 0.0002

WS amplifier gain w(Gws) 0 V A"

1 BB amplifier calibration correction m(Ca,bb) 0.001

BB linearity correction w(Cl.bb) 0.001

BB size of source correction "(Cs ,bb) 0.0002

BB amplifier gain m(Gbb) 0 VA"1

Digital voltmeter w(DMM) OK

BB temperature w(Tbb) 2.29 K

Blackbody uniformity w(BU) 0.20 K

RT reading w(RTR) 2.00 K

RT temperature calibration w(Trt) 3.05 K

52
7. Modifications to the NIST photoelectric pyrometer

The radiance temperature calibrations described in this document are performed using

the NIST PEP, which is a single wavelength instrument. The spectral radiance temperatures at 900 nm and 1000 nm are calculated from measurements made at 655.3 nm. Modifications to the

PEP are underway to allow direct measurements at 900 nm and 1000 nm. The modified

pyrometer also uses refractive optics, interference filters, and a photomultiplier tube. The

modifications will include adding a filtered silicon detector and amplifier system, and a laser to simplify source alignments. A schematic of the modified PEP is shown in figure 24. The

methods described in the report to realize the radiance temperature scale at 655.3 nm will be

employed to realize the scale in the infrared.

OL

n

i I A/.

LEGEND

AS Aperture Stop CL Colllmating Lens CPD Cooled Photomultiplier Detector DL Diverging Lens

FS 0.6 mm x 0.8 mm

Rectangular Field Stop FW Filter Wheel GPBB Gold-point Blackbody GPL Gold-point Lamp

HeNe Helium-Neon Laser

IF Interference Filters L Lens OL Ob|ectlve Lens PM Plane Mirror

SI Silicon Detector

TL Test Lamp

VTBB Variable Temperature Blackbody WSL Working Standard Lamp

Figure 24. Modified NIST photoelectric pyrometer.

53
Acknowledgments

The authors would like to thank Robert D. Saunders for his technical assistance in

reading the manuscript and his constant encouragement. They also like to thank Frank Lovas,

Dean Ripple, and Chris Kuyatt for useful suggestions and comments.

54
References

[I] Mielenz, K.D., Saunders, R.D., Parr, A.C., and Hsia, J. J., "The 1990 NIST Scales of

Thermal Radiometry," J. Res. NIST, 95, 621 (1990).

[2] Preston-Thomas, H., "The International Temperature Scale of 1990 (ITS-90)," Metrologia,

27, 3-10, 107(1990).

[3] Taylor, B.N., and Kuyatt, C.E., "Guidelines for Evaluating and Expressing the Uncertainty

of NIST Measurement Results," NIST TN 1297 (2nd ed., 1994).

[4] Simmons, J.D. Ed., "NIST Calibration Services Users Guide," NIST SP 250, 69 (1991).

[5] Kostkowski, H.J., and Nicodemus, F.E., "An Introduction to the Measurement Equation,

Chapter 5 of Self-Study Manual on Optical Radiation Measurements: Part I - Concepts,"

NBSTN 910-2, 58(1978).

[6] Planck, M., "Distribution of Energy in the Spectrum," Ann. Phys., 4, 3, 553 (1901).

[7] Cohen, E.R. and Taylor, B.N., "The 1986 Adjustment of the Fundamental Physical

Constants," Review ofModern Physics, 59, 4, 1 121 (1987).

[8] Lide, D.R., "CRC Handbook of Chemistry and Physics," CRC Press, 67th ed., E-373

(1986-1987).

[9] Quinn, T.J., "Temperature," Academic Press Inc., San Diego, CA, 380 (1990).

[10] Saunders, R.D., Gibson, C.E., Mielenz, K.D., Sapritsky, V.I., Sudarev, KA., Khlevnoy,

B.B., Mekhontsev, S.N, and Harchenko, G.D. , "Results of a NIST/VNIIOFI Comparison

of Spectral-Radiance Measurements," Metrologia, 32, 449 (1995/1996).

[II] Quinn, T.J. and Lee, R.D., "Vacuum Tungsten Strip Lamps with Improved Stability as Radiance Temperature Standards," Temperature, Its Measurement and Control in Science

and Industry, Instrument Society of America, Pittsburgh, 4, 1, 395 (1972).

[12] Lee, R.D., Kostkowski, H.J., Quinn, T.J., Chandler, P.R., Jones, T.N., Tapping, J., and

Kunz, H., "Intercomparison of the IPTS68 Above 1064°C by Four National Laboratories,"

Temperature, Its Measurement and Control in Science and Industry, Instrument Society of

America, Pittsburgh, 4, 1, 377 (1972).

[13] Eckerle, K.L., Hsia, J.J., Mielenz, K.D., and Weidner, V.R., "Regular Spectral

Transmittance," NBS SP 250-6 (1987).

55
[14] Saunders, R.D. and ShumakerJ.B., "Automated Radiometric Linearity Tester," Appl. Opt.,

23, 20, 3504,(1984).

[15] Larason, T.C., Bruce, S.S., and Cromer, C.L., "The NIST High Accuracy Scale for

Absolute Spectral Response from 406 nm to 920 nm," J. Res. NIST, 101, 2, 133 (1996).

[16] Mielenz, K.D., Saunders, R.D., and Shumaker, J. B., "Spectroradiometric Determination of

the Freezing Temperature of Gold," /. Res. NIST, 95, 49 (1990).

[17] "American National Standard for Calibration - Calibration Laboratories and Measuring and

Test Equipment - General Requirements," ANSI/NCSL Z540- 1-1994.

[18] "ISO Guide 25 General requirements for the competence of calibration and testing

laboratories," 3rd edition (1990).

[19] Bruce, S.S. and Larason, T.C., "Developing Quality System Documentation Based on ANSI/NCSL Z540- 1-1994 : The Optical Technology Division's Effort," NISTIR 5866

(1996).

[20] Johnson, B.C., Gibson, C, Machin, G., and Rusby, R.L., "Intercomparison of the ITS-90

radiance temperature scales of the national physical laboratory and NIST," J. Res. NIST, 99,

731 (1994).

[21] Johnson, B.C., Sakuma, F., Sakate, H., Gibson, C, Machin, G., Ricolfi, T., Battuello, M.,

Fischer, J., and Jung, H.J., "International comparison of radiation temperature scales among

five national metrological laboratories using a transfer standard radiation thermometer,"

Metrolgia, 33, 241 (1996).

[22] Kostkowski, H.J., and Lee, R.D. "Theory and Methods of Optical Pyrometry," NBS

Monograph 41, (1962).

56
Appendix A: Ribbon filament lamp sample calibration report

In reply refer to: 844/1 23456-95

Radiometric Systems Inc. Attn: John Doe

123 Calibration Court

Measurement City, MD 00000-0000

Subject: Ribbon Filament Lamp Report of Calibration

Order No. : AB 1 234 dated January 1,1995

Dear Mr. Doe:

Enclosed are results of the calibration you requested for Test Number 35050C Radiance

Temperature Standard, Ribbon Filament Lamp. Please refer to the above file number in

further communication concerning this calibration.

Sincerely,

Albert C. Parr, Chief

Optical Technology Division

Physics Laboratory

Enclosures:

One Report of Calibration

ACP/jah

NIST Cost Center 8443600

A1
REPORT OF CALIBRATION

35050C Radiance Temperature Standard,

Ribbon Filament Lamp

for

Model # General Electric 30A/T24/6, Serial # P000

Submitted by:

John Doe

Radiometric Systems Inc. 123 Calibration Court

Measurement City, MD 00000-0000

(See your Purchase Order No. AB 1 234 dated January 1 , 1995)

1. Description of Calibration Item

A gas-filled tungsten ribbon filament lamp with a mogul screw base was calibrated by the

National Institute of Standards and Technology (NIST) as a standard of radiance temperature

from 1000 °C to 2200 °C. The serial number is located on the rear of the lamp envelope

opposite the side viewed by the pyrometer.

2. Description of Calibration

The lamp was calibrated in the NIST Radiance Temperature Calibration Facility using the

equipment and procedures described in Ref. [11. The NIST Photoelectric Pyrometer, which has a mean effective wavelength of 655.3 nm, was used to spectrally compare the test lamp to working

standard SL20 to determine its radiance temperature at each test lamp current. The NIST

Photoelectric Pyrometer is described in the Ref. [1].

The orientation and operation of the test lamp is described in the enclosed NIST SP250-43

entitled, "Radiance Temperature Calibrations." The calibration was performed with the lamp

operating on direct current and with the center contact of the lamp base at positive potential. The

lamp was aligned base down while operating at a radiance temperature of 1700 °C.

Laboratory Environment:

Temperature: 24 °C ± 1 °C

Relative Humidity: 25% ± 5%

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95

A2

Page 1 of 5
REPORT OF CALIBRATION

35050C Radiance Temperature Standard, Ribbon Filament Lamp Model #: GE 30A/T24/6

Radiometric Systems Inc. Serial #: P000

3. Results of Calibration

Table 1 gives the radiance temperature of the test lamp at 655.3 nm versus the test lamp current.

Table 2 gives the calibration uncertainties in relative to the International System of Units (SI

Units). The expanded uncertainties U = kuc (T) (coverage factor k = 2) are two standard deviation

estimates. Details on the estimation of these uncertainties are given in Ref. [1]. The NIST policy on uncertainty statements is described in Ref. [3].

4. General Information

The temperatures described in this report are radiance temperatures. The temperatures are stated

with respect to the 1990 NIST Radiance Temperature Scale and correspond to temperatures when

sighting on a Planckian radiator. See Ref. [2] for further details on the 1990 NIST Radiance

Temperature Scale.

To maintain the highest accuracy, keep the lamp envelope clean and have the lamp recalibrated

periodically. Appropriate calibration schedules vary with lamp and application and are best

determined by the user.

The following was taken from Barber [4]. The radiance temperature below 1500 °C for gas-filled

lamps and 900 °C for vacuum lamps will change as the room or ambient temperature changes.

Barber observed a change in radiance temperature for a gas-filled lamp of between 0.3 °C and

0.4 °C per 1 °C change in room temperature at 1000 °C and 0.05 °C per 1 °C change in room

temperature at 1400 °C. Changes of the same magnitude were observed at 700 °C and 900 °C for a vacuum lamp.

The results of this calibration apply only to the lamp referenced in this report. This report shall

not be reproduced, except in full, without the written approval of the Radiance Temperature

Measurements Calibration Service.

Prepared by: Approved by:

Charles E. Gibson

Optical Technology Division

Physics Laboratory

(301) 975-2329

Robert D. Saunders

For the Director,

National Institute of

Standards and Technology

(301) 975-2355

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95 Page 2 of 5

A3
REPORT OF CALIBRATION

35050C Radiance Temperature Standard, Ribbon Filament Lamp Model #: GE 30A/T24/6

Radiometric Systems Inc. Serial #: P000

References

[1] C. E. Gibson, B. K. Tsai, and A. C. Parr, "Radiance Temperature Calibrations," NIST

Special Publication 250-43 (1997).

[2] K. D. Mielenz, R. D. Saunders, A. C. Parr, and J. J. Hsia, "The 1990 NIST Scales of

Thermal Radiometry," /. Res. Natl. Inst. Stand. Technol., 95, 621-629, (1990).

[3] B. N. Taylor and C. E. Kuyatt, "Guidelines for Evaluating and Expressing the Uncertainty

of the NIST Measurement Results," NIST Technical Note 1297 (2nd ed., 1994).

[4] C. R. Barber, "Factors affecting the reproducibility of brightness of tungsten strip lamps for

pyrometry standardization," J. Sci. Instr. 23, 238 (1946).

Calibration Date: January 2, 1995

NIST Test No. : 844/ 1 23456-95

A4

Page 3 of 5
REPORT OF CALIBRATION

35050C Radiance Temperature Standard, Ribbon Filament Lamp

Radiometric Systems Inc. Model #: GE 30A/T24/6

Serial #: P000

TABLE 1 Radiance Temperature of Lamp P000 at 655.3 nm

Radiance

Temperature

(1990 NIST)

L

Lamp

Current

[A]

1000 12 945

1100 14 220

1200 15 698

1300 17 358

1400 19 191

1500 21 155

1600 JLvvv 23 246

1700 25.449

1800 27.757

1900 30.175

2000 32.669

2100 35.254

2200 37.922

Calibration Date: January 2, 1 995

NIST Test No.: 844/123456-95

A5

Page 4 of 5
REPORT OF CALIBRATION

35050C Radiance Temperature Standard, Ribbon Filament Lamp

Radiometric Systems Inc. Model #: GE 30A/T24/6Serial #: P000

TABLE 2

Radiance Temperature Calibration Uncertainties

Source of Uncertainty Type

Expanded Uncertainties (k = 2) [°C]

800 °C 1100°C 1500 °C 1900 °C 2300 °C

1 . Calibration of the reference

radiance temperature lamp

relative to the 1 990 NTST

Radiance Temperature Scale

B 0.12 0.19 0.32 0.48 0.67

2. Test lamp temperature

determination

A 0.42 f\ in 0.17 0.29 0.43 0.60

3. Current measurement B 0.29 0.19 0.15 0.14 0.14

4. Mean effective wavelength

measurement for the NIST

Photoelectric Pyrometer

B 0.10 0.04 0.09 0.28 0.54

5. Test lamp alignment B 0.09 0.14 0.24 0.36 0.51

6. 1990 NIST Radiance

Temperature Scale relative to the Thermodynamic

Temperature Scale

B 0.15 0.24 0.40 0.61 0.85

Overall uncertainty of test lamp

calibration with respect to SI units

0.6 0.4 0.7 1.0 1.5

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95

A6

Page 5 of 5
Appendix B: Optical pyrometer sample calibration report

In reply refer to: 844/123456-95

Radiometric Systems Inc. Attn: John Doe

123 Calibration Court

Measurement City, MD 00000-0000

Subject: Optical Pyrometer Report of Calibration

Order No. : AB 1 234 dated January 1,1995

Dear Mr. Doe:

Enclosed are results of the calibration you requested for Test Number 35040C Radiance

Temperature Standard, Disappearing Filament Optical Pyrometer. Please refer to the above file number in any further communication concerning this calibration.

Sincerely,

Albert C. Parr, Chief

Optical Technology Division

Physics Laboratory

Enclosure:

One Report of Calibration

ACP/jah

NIST Cost Center 8443600

B1
REPORT OF CALIBRATION

35040C Radiance Temperature Standard,

Disappearing Filament Optical Pyrometer

for

Model # Leeds and Northrup 863 1-F, Serial # 0000000

Submitted by:

John Doe

Radiometric Systems Inc. 123 Calibration Court

Measurement City, MD 00000-0000

(See your Purchase Order No. AB1234 dated January 1, 1995)

1. Description of Calibration Item

An optical pyrometer was tested by the National Institute of Standards and Technology (NIST) as a standard of radiance temperature from 1 149 °C (2100 °F) to 1482 °C (2700 °F).

2. Description of Calibration

The test pyrometer was measured in the NIST Radiance Temperature Calibration Facility using

the equipment and procedures described in Ref. [1]. The NIST Photoelectric Pyrometer, which

has a mean effective wavelength of 655.3 nm, was used to spectrally compare the variabletemperature blackbody to working standard SL20 to determine the radiance temperature of the

blackbody at each calibration temperature. The portion of the test pyrometer lamp filament

below the wire marker was matched in brightness to that of the blackbody and the test pyrometer

scale reading was recorded at each calibration temperature. The NIST Photoelectric Pyrometer is described in the Ref. [ 1 ]

The variable-temperature blackbody has an estimated emissivity of 0.99. The blackbody cavity

is a single piece of graphite, specially tapered for temperature uniformity. This graphite tube is cylindrically hollow on both ends to form two 2.54 cm diameter cavities with a common partition

in the center. One cavity is used for temperature control and the other as a blackbody source.

Laboratory Environment:

Temperature: 23 °C ± 1 °C

Relative Humidity: 46% ±5%

Calibration Date: January 2, 1995

NIST Test No.: 844/1 23456-95 Page 1 of 5

B2
REPORT OF CALIBRATION

35040C Radiance Temperature Standard, Optical Pyrometer

Radiometric Systems Inc. Model #: L&N 8631-FSerial #: 0000000

The test pyrometer was operated according to the manufacturer's operating instructions. The

pyrometer was calibrated from 1 149 °C (2100 °F) to 1482 °C (2700 °F) on the high range (H).

The pyrometer was aligned so that its optical axis, when viewing the variable-temperature

blackbody, coincided with the geometrical center of the blackbody. The pyrometer was

measured at a distance of 81 .7 cm from the front surface of the objective lens holder to the

blackbody cavity partition and was focussed on the center of the partition.

3. Results of Calibration

Table 1 gives the radiance temperature at 655.3 nm versus the test pyrometer scale reading.

Table 2 gives the calibration uncertainties relative to the International System of Units (SI Units).

The expanded uncertainties U = kuc (T) (coverage factor k = 2) are two standard deviation

estimates. Details on the estimation of these uncertainties are given in Ref. [1]. The NIST policy on uncertainty statements is described in Ref. [3].

4. General Information

The temperatures described in this report are radiance temperatures. The temperatures are stated

with respect to the 1990 NIST Radiance Temperature Scale and correspond to temperatures when

sighting on a Planckian radiator. See Ref. [2] for further details on the 1990 NIST Radiance

Temperature Scale.

To maintain the highest accuracy, keep the optical components clean and have the pyrometer

recalibrated periodically. Appropriate calibration schedules vary with instrument and application

and are best determined by the user.

The results of this calibration apply only to the pyrometer referenced in this report. This report

shall not be reproduced, except in full, without the written approval of the Radiance Temperature

Measurements Calibration Service.

Prepared by:

Charles E. Gibson

Optical Technology Division

Physics Laboratory

(301)975-2329

Approved by:

Robert D. Saunders

For the Director,

National Institute of

Standards and Technology

(301)975-2355

Calibration Date: January 2, 1 995

NIST Test No.: 844/123456-95

B3

Page 2 of 5
REPORT OF CALIBRATION

35040C Radiance Temperature Standard, Optical Pyrometer

Radiometric Systems Inc. Model #: L&N 863 1-F

Serial #: 0000000

References

[1] C. E. Gibson, B. K. Tsai, and A. C. Parr, "Radiance Temperature Calibrations," NIST

Special Publication 250-43 (1997).

[2] K. D. Mielenz, R. D. Saunders, A. C. Parr, and J. J. Hsia, "The 1990 NIST Scales of

Thermal Radiometry," J. Res. Natl. Inst. Stand. Technol., 95, 621-629, (1990).

[3] B. N. Taylor and C. E. Kuyatt, "Guidelines for Evaluating and Expressing the Uncertainty

of the NIST Measurement Results," NIST Technical Note 1297 (2nd ed., 1994).

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95 Page 3 of 5

B4
REPORT OF CALIBRATION

35040C Radiance Temperature Standard, Optical Pyrometer

Radiometric Systems Inc. Model #: L&N 8631-F

Serial #: 0000000

TABLE 1 Radiance Temperature at 655.3 nm

Nominal

Temperature

[°C]

Blackbody

Temperature

(1990 NIST)

[°C]

Blackbody

Temperature

[°F]

Pyrometer

Scale Reading

Value [°F]

Pyrometer

Correction

[°F]

High range (H)

1148.9 1149.2 2100.6 2098 3

1315.6 1316.5 2401.7 2401 1

1482.2 1482.9 2701.2 2700 1

This equation was used to convert the blackbody temperature T from °C to °F:

r/°F = (1.8x77°C) + 32

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95

B5

Page 4 of 5
REPORT OF CALIBRATION

35040C Radiance Temperature Standard, Optical Pyrometer

Radiometric Systems Inc. Model #: L&N 863 1-F

Serial #: 0000000

TABLE 2

Radiance Temperature Calibration Uncertainties

Source of Uncertainty Tvoe

Expanded Uncertainties (k = 2)

[°C (°F)]

1148.9 °C 1315.6 °C 1482.2 °C

(2100 °F) (2400 °F) (2700 °F)

1 . Calibration of the variable temperature

blackbody relative to the 1990 NIST

lxu.LiIo.IlCC 1 ClllUvluLUlw Jtait/

B

0.3

(0.6)

0.4

(0.7)

0.4

(0.7)

2. Mean effective wavelength measurement for

the NIST Photoelectric Pyrometer

B

0.0

(0.0)

0.0

(0.0)

0.1

(0.2)

3. Blackbody uniformity B

0.2

(0.4)

0.2

(0.4)

0.2

(0.4)

4. Test pyrometer temperature determination A

1.1 (2.0)u

(2.0)

2.2

(4.0)

5. 1990 NIST Radiance Temperature Scale

relative to the Thermodynamic Temperature

Scale

B

0.3

(0.5)

0.3

(0.6)

0.4

(0.7)

Overall uncertainty of test lamp calibration with

respect to SI units

1.2

(2.2)

1.2

(2.2)

2.3

(4.1)

Note: The expanded uncertainties in parentheses are in °F. The following equation was used to convert the blackbody temperature Tfrom °C to °F: 77°F = (1.8 x 77°C) + 32

Calibration Date: January 2, 1995

NIST Test No.: 844/123456-95 Page 5 of 5

B6
Appendix C: Radiation thermometer sample calibration report

In reply refer to: 844/1 23456-95

Radiometric Systems Inc. Attn: John Doe

123 Calibration Court

Measurement City, MD 00000-0000

Subject: Radiation Thermometer Report of Test

Order No. : AB 1 234 dated January 1,1995

Dear Mr. Doe:

Enclosed are results of the test you requested for Test Number 35070S Special Test of Radiation

Thermometer. Please refer to the above file number in any further communication concerning

this test.

Sincerely,

Albert C. Parr, Chief

Optical Technology Division

Physics Laboratory

Enclosure:

One Report of Test

ACP/jah

NIST Cost Center 8443600

C1
REPORT OF TEST

35070S Special Test of Radiation Thermometer

for

Model # Minolta-Land Cyclops 52, Serial # 00000000

Submitted by:

John Doe

Radiometric Systems Inc. 123 Calibration Court

Measurement City, MD 00000-0000

(See your Purchase Order No. AB1234 dated January 1, 1995)

1. Description of Test Item

A radiation thermometer was tested by the National Institute of Standards and Technology

(NIST) as a standard of radiance temperature from 800 °C to 2300 °C. The test unit was

measured with clear filter (Serial Number 0) and dark filter (Serial Number 0).

2. Description of Test

The test thermometer was measured in the NIST Radiance Temperature Calibration Facility

using the equipment and procedures described in Ref. [1]. The NIST Photoelectric Pyrometer,

which has a mean effective wavelength of 655.3 nm, was used to spectrally compare the variabletemperature blackbody to working standard SL20 to determine the radiance temperature of the

blackbody at each calibration temperature. The test thermometer display panel value was

recorded at each calibration temperature. The NIST Photoelectric Pyrometer is described in the

Ref. [1]

The variable-temperature blackbody has an estimated emissivity of 0.99. The blackbody cavity

is a single piece of graphite, specially tapered for temperature uniformity. This graphite tube is cylindrically hollow on both ends to form two 2.54 cm diameter cavities with a common partition

in the center. One cavity is used for temperature control and the other as a blackbody source.

Laboratory Environment:

Temperature: 23 °C ± 1 °C

Relative Humidity: 46% ± 5%

Test Date: January 2, 1 995

NIST Test No.: 844/123456-95 Page 1 of 5

C2
REPORT OF TEST

35070S Special Test of Radiation Thermometer

Radiometric Systems Inc. Model #: Minolta-Land Cyclops 52

Serial #: 00000000

The thermometer was aligned so that its optical axis, when viewing the variable-temperature

blackbody, coincided with the geometrical center of the blackbody. The test thermometer was

operated according to the manufacturer's operating instructions and measured with the following

conditions.

Temperatures measured: 800 °C to 1200 °C with the clear filter

1 200 °C to 2300 °C with the dark filter

Distance:

Operating mode:

Calculated target size:

Emissivity setting:

3. Results of Test

100 cm from the thermometer alignment mark to the blackbody

cavity partition

continuous mode

5.6 mm diameter focused on the center of the blackbody cavity

partition

1

Table 1 gives the radiance temperature at 1000 nm versus the test thermometer display panel

value.

Table 2 gives the test uncertainties relative to the International System of Units (SI Units). The

expanded uncertainties U - kuc (T) (coverage factor k = 2) are two standard deviation estimates.

Details on the estimation of these uncertainties are given in Ref. [1]. The NIST policy on

uncertainty statements is described in Ref. [3].

4. General Information

The temperatures described in this report are radiance temperatures. The temperatures are stated

with respect to the 1990 NIST Radiance Temperature Scale and correspond to temperatures when

sighting on a Planckian radiator. See Ref. [2] for further details on the 1990 NIST Radiance

Temperature Scale.

To maintain the highest accuracy, keep the optical components clean and have the thermometer

recalibrated periodically. Appropriate calibration schedules vary with instrument and application

and are best determined by the user.

The results of this test apply only to the thermometer referenced in this report. This report shall

not be reproduced, except in full, without the written approval of the Radiance Temperature

Measurements Calibration Service.

Test Date: January 2, 1 995

NIST Test No.: 844/123456-95 Page 2 of 5

C3
REPORT OF TEST

35070S Special Test of Radiation Thermometer

Radiometric Systems Inc. Model #: Minolta-Land Cyclops 52

Serial #: 00000000

Prepared by: Approved by:

Charles E. Gibson

Optical Technology Division

Physics Laboratory

(301)975-2329

Robert D. Saunders

For the Director,

National Institute of

Standards and Technology

(301)975-2355

References

[1] C. E. Gibson, B. K. Tsai, and A. C. Parr, "Radiance Temperature Calibrations," NIST

Special Publication 250-43 (1997).

[2] K. D. Mielenz, R. D. Saunders, A. C. Parr, and J. J. Hsia, "The 1990 NIST Scales of

Thermal Radiometry," J. Res. Natl. Inst. Stand. Technol., 95, 621-629, (1990).

[3] B. N. Taylor and C. E. Kuyatt, "Guidelines for Evaluating and Expressing the Uncertainty

of the NIST Measurement Results," NIST Technical Note 1297 (2nd ed., 1994).

Test Date: January 2, 1995

NIST Test No.: 844/123456-95 Page 3 of 5

C4
REPORT OF TEST

35070S Special Test of Radiation Thermometer

Radiometric Systems Inc. Model #: Minolta-Land Cyclops 52

Serial #: 00000000

TABLE 1 Radiance Temperature at 1000 nm

Nominal

Temperature

[°C]

Blackbody

Temperature

(1990 NIST)

[°C]

Thermometer

Display Panel

Value

[°C]

Thermometer

Correction

[°C]

Clear Filter

800 798.7 801 -2.3

900 899.1 900 -0.9

1000 1000.2 1000.5 -0.3

1100 1 100.6 1100.5 0.1

1200 1200.5 1199.5 1.0

Dark filter

1200 1200.4 1200 0.4

1300 1299.4 1298 1.4

1400 1399.6 1396.5 3.1

1500 1500.3 1497 3.3

1600 1600.6 1597 3.6

1700 1700.5 1696.5 4.0

1800 1801.7 1797 4.7

1900 1899.5 1894 5.5

2000 1999.9 1992 7.9

2100 2099.9 2091.5 8.4

2200 2200.7 2191 9.7

2300 2301.2 2290 11.2

Test Date: January 2, 1995

NIST Test No.: 844/123456-95 Page 4 of 5

C5
REPORT OF TEST

35070S Special Test of Radiation Thermometer

Radiometric Systems Inc. Model #: Minolta-Land Cyclops 52

Serial #: 00000000

TABLE 2

Radiance Temperature Test Uncertainties

Source of Uncertainty Type

Expanded Uncertainties (k = 2) [°C]

800 °C 1100°C 1500 °C 1900 °C 2300 °C

1 . Calibration of the variable

temperature blackbody

relative to the 1990 NIST

Radiance Temperature Scale

B 0.3 0.3 0.4 0.6 0.9

2. Mean effective wavelength

measurement for the NIST

Photoelectric Pyrometer

B 0.1 0.0 0.1 0.3 0.5

3. Blackbody temperature

correction

B 0.1 0.2 0.4 0.6 0.8

4. Blackbody uniformity B 0.2 0.2 0.2 0.2 0.2

5. Test thermometer temperature

determination

A 2.0 2.0 2.0 2.0 2.0

6. 1990 NIST Radiance

Temperature Scale relative to the Thermodynamic

Temperature Scale

B 0.1 0.2 0.4 0.6 0.9

Overall uncertainty of test lamp

calibration with respect to SI units

2.0 2.1 2.1 2.3 2.5

Test Date: January 2, 1995

NIST Test No.: 844/123456-95

C6

Page 5 of 5
Appendix D: Radiance temperature measurement services laboratory procedure manual

Radiance Temperature Measurements

Laboratory Procedures Manual

v J

D1
Safety Issues

Safety glasses are required in lab at all times.

The following hazards have been identified in this lab. Safety measures are in place to reduce

risk of injury from hazards below.

BRIGHT SOURCE

Staring at source is to be avoided because staring can cause severe eye damage. Using correct

neutral density filter when viewing is required

BURN

To avoid burns, it is wise to keep body and clothes away from lamps and blackbodies.

COLLISION

The boxcar path should be kept clear of collision with any objects, and cables should not be hung

from boxcar at any time.

ELECTROCUTION

Since high voltage connections are present, electrical parts should not be touched at all. LASER

As with other bright sources, staring into laser is to be avoided because staring can cause severe eye damage. When lasers are not in use, block laser with opaque object and turn off laser when it

is not in use.

Symbols, similar to one below, are used throughout this document to alert operator to potential

hazards.

LASER

G:\LPManual\RTMLP Safety. 1 D2

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedures

Table of Contents

i. Safety Issues

1. Running General Data Taking Program (RTMLP 1

)

2. NIST Photoelectric Pyrometer (PEP) Operation (RTMLP2)

3. Gold-point Blackbody (GPBB) Alignment (RTMLP3)

4. Gold-point Blackbody Operation (RTMLP4)

5. Ribbon Filament Lamp Preparation (RTMLP5)

6. Ribbon Filament Lamp Alignment (RTMLP6)

7. Ribbon Filament Lamp Operation (RTMLP7)

8. Ribbon Filament Lamp Calibration Procedure (RTMLP8)

9. Ribbon Filament Lamp Data Reduction (RTMLP9)

10. Variable Temperature Blackbody (BB) Alignment (RTMLP10)

11. Variable Temperature Blackbody Operation (RTMLP 1 1)

12. Disappearing Filament Optical Pyrometer Alignment (RTMLP 12)

13. Radiation Thermometer (RT) Alignment (RTMLP 13)

14. Radiation Thermometer (Optical Pyrometer) Calibration Procedure (RTMLP 14)

15. Radiation Thermometer Data Reduction (RTMLP 15)

G:\LPManual\RTMTOC. 1

D3

Page 1 of 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Running General Data Taking Program

Written by:

Approved by:

Revised by:

Charles Gibson Procedure: RTMLP1

Date: _

Date:

Running the General Data Taking Program

1 . Turn on computer

2. Enter password to work online or click on Cancel button to work offline

3. Load Visual Basic program: c:\programs\datatakn\pyro.mak (do one of following)

a. Click on Pyro.mak shortcut icon

b. Double click on folder c: \programs\datatakn\pyro. mak using Windows Explorer

4. Run program (do one of following)

a. Press F5

b. Click on tool bar icon

c. Click on menu item "Run" then "Start"

5. Run Hardware.frm to set up equipment with settings used by other programs

6. Run Software.frm to input data used by other programs

7. Run all other programs from these forms

G:\LPManual\RTMLPl.l

D4

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

NIST Photoelectric Pyrometer (PEP) Operation

Written by: Charles Gibson Procedure: RTMLP2

Approved by: Date:

Revised by: Date:

NIST Photoelectric Pyrometer (PEP) Operation

1 . Turn on equipment

a. PMT thermoelectric cooler

b. Digital multimeters

c. Motor controller

d. High voltage power supply

e. Current amplifier

f. Environment monitor

TO

LASER

2. Check alignment of optics

a. Align laser on source table so that beam goes through center of pin hole aperture

and field stop

b. Check that collimating lens is centered on and normal to optical axis

(retroreflection checked at field stop)

c. Check that aperture stop is centered on and normal to optical axis (place

microscope slide against aperture stop to check retroreflection at field stop)

d. Check scope alignment (see step 3)

e. Check that lamp beam is centered on aperture stop

f. Record aperture stop micrometer position in lab notebook

BRIGHT SOURCE

BURN

COLLISION

ELECTROCUTION

G:\LPManual\RTMLP2.1

D5

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP2: Photoelectric Pyrometer (PEP) Operation

3. Check scope alignment (scope is used to define optical axis of PEP)

a. Turn on SL20 or other lamp in focal plane of PEP (see RTMLP7)

b. Move lamp to PEP

c. Close PMT shutter

d. Open enclosure doors

e. Open scope door

f. Place 3/4" aperture on objective lens

g. Put in field stop

h. Put in prism

i. Focus reticle to operator's eye

j. Focus scope on field stop

k. Rotate reticle so that #5 vertical scale line is parallel to side of field stop opening

1. Position reticle center (intersection of #5 vertical scale line and horizontal scale

line) on field stop opening m. Remove prism

n. Remove field stop

o. Put in prism

4. Set up PEP for measurements

a. Remove aperture from objective lens

b. Remove prism

c. Close scope door

d. Put in field stop

e. Close all enclosure doors

f. Position baffles at front of PEP

g. Open PMT shutter

h. Begin calibration (see (RTMLP8) for lamps or (RTMLP14) for radiation

thermometers)

G:\LPManual\RTMLP2.

D6

Page 2
, Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Gold-point Blackbody (GPBB) Alignment

Written by: Charles Gibson Procedure: RTMLP3

Approved by: Date:

Revised by: Date:

WBMllWni^

Gold-point Blackbody (GPBB) Alignment

COLLISION

LASER

1 . Align laser on source table so that beam goes through center of pin hole aperture and field

stop

2. Move first laser to laser on PEP table

3. Align second laser so that it coincides with first laser

4. Remove outer most graphite ring

5. Put in alignment jig

6. Translate GPBB to center jig on laser

7. Rotate GPBB to make jig normal to laser (retroreflect laser beam)

8. Turn on GPBB (see RTMLP4)

9. Radiometrically center GPBB

a. Center X along horizontal axis

b. Center Y along vertical axis

c. Center <X about horizontal axis

d. Center <Y about vertical axis

e. Make -8 turns along optical axis

f- Repeat steps a and b until centered

g. Check centering

i. Monitor BB signal on graph logger

ii. Hold card in front of BB opening

iii. Check for equal signal drop-offs when blocking top, bottom, left, and right

portions of BB opening

G:\LPManual\RTMLP3 .

D7

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Gold-point Blackbody Operation

Written by: Charles Gibson Procedure: RTMLP4

Approved by: Date:

Revised by: Date:

Gold-point Blackbody (GPBB) Operation

TO

BRIGHT SOURCE

BURN

ELECTROCUTION

1. Close GPBB door

2. Turn on cold water at flow rate of 10 GPH

3. Set argon at flow rate of 54 mL/min (set black ball to 50)

4. Go to rack of power supplies

5. Turn on digital multimeter

6. Check that correct cable is connected to GPBB power supply connector

7. Switch on power supply (labeled HPPS)

8. Run lamp current monitoring program

a. Turn on computer

b. Type 2 and press [Enter] at DOS prompt to load and run lamp monitoring

program

c. Prepare GPBB

i. Ramp up GPBB

( 1 ) Ramp up GPBB to about 1 040 ° C

(2) Set current at 2 A

(3) Wait 3 h

(4) Ramp up to 8 A in 4 h (ramping rate 1 .5 A/h)

(5) Set GPBB temperature to about 1040 °C in 8 h to 10 h

ii. Press 8 to ramp up GPBB

iii. Type (start time) and press [Enter]

iv. program will start ramping up GPBB at start time

G:\LPManual\RTMLP4.1

D8

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP4: Gold-point Blackbody Operation

d. Cycle GPBB through melt and freeze cycles

i. Press 3 to monitor lamps and read GPBB temperature

ii. Press [Esc] to return to main menu

iii. Set current to 8.5 A and begin GPBB melt cycle when set point falls below

1050 °C

iv. Set current to 7.95 A and begin GPBB freeze cycle when set point rises

above 1071 °C

9. Set argon at flow rate of 235 mL/min (set black ball to 1 20)

10. Open GPBB door

11. Turn off GPBB

a. Close GPBB door

b. Set argon at flow rate of 54 mL/min (set black ball to 50)

c. Turn of power to GPBB

d. Leave water and argon on overnight until GPBB is cool

G:\LPManual\RTMLP4.

D9

Page 2
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Ribbon Filament Lamp Preparation

Written by: Charles Gibson Procedure: RTMLP5

Approved by: Date:

Revised by: Date:

Ribbon Filament Lamp Preparation

BRIGHT SOURCE

BURN

ELECTROCUTION

Lamp inspection

a. Check filament continuity

b. Check clarity of envelope (and window)

c. Check flatness of filament

d. Check that filament is within 2 mm of being centered in envelope (or window)

Clean lamp envelope

Anneal lamp

a. Anneal gas lamp

i. Leak test lamp

(!) Set lamp to 1700 °C (PMT signal = 2.5 V on 8 range, high

voltage = 449 V) (About 25 A dc)

(2) Turn off lamp

(3) Wait 1 5 min to allow air to enter any leaks

(4) Set lamp to 2350 °C (PMT signal = 1 .2 V on 7 range, high

voltage = 394 V)(About 45 A dc)

(5) Wait 15 min

ii. Anneal lamp for 2 h

iii- Age lamp for 50 h at 2300 °C (About 42 A dc)

G:\LPManual\RTMLP5 .

Page 1

D10
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP5: Ribbon Filament Lamp Preparation

b. Anneal vacuum lamp

i. Leak test lamp

(1) Set lamp to 1000 °C (PMT signal = 5.3 V on 9 range, high

voltage = 730 V)

(2) Turn off lamp

(3) Wait 15 min to allow air to enter any leaks

(4) Set lamp to 1450 °C (PMT signal - 5. 1 V on 9 range, high

voltage = 449 V)

(5) Wait 15 min

ii. Anneal lamp for 14 h

4. Locate arrow on lamp

a. Set lamp to 1700 °C for gas lamps or 1200 °C for vacuum lamps (for 1200 °C,

PMT signal = 5.5 V on 8 range, high voltage = 730 V)

b. Use plumb line to make notch side of filament vertical

c. Translate lamp horizontally so that reticle center bisects filament lengthwise

d. Translate lamp vertically so that reticle center is positioned at center of notch

opening

e. Translate lamp along optical axis until filament is in focus

f. Rotate lamp about vertical axis so that both edges of filament are in focus

g. Use graph logger to locate angular settings with smallest change in radiance with

respect to rotation about horizontal and vertical axes

h. First person looks through alignment scope and guides second person to notch

i. Second person makes dot on lamp envelope at notch

j. Draw picture of notch in lab notebook showing its relationship to dot

k. Draw arrow showing relationship of alignment arrow to dot

1. Repeat steps for each lamp

G:\LPManual\RTMLP5.1

D11

Page 2
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Ribbon Filament Lamp Alignment

Written by: Charles Gibson Procedure: RTMLP6

Approved by: Date:

Revised by: Date:

Ribbon Filament Lamp Alignment

BRIGHT SOURCE

BURN

COLLISION

ELECTROCUTION

1 . Check PEP scope alignment (see RTMLP2)

2. Place 3/4" aperture on objective lens

3. Turn on lamp (see RTMLP7)

4. Move lamp to PEP optical axis

5. Use plumb line to make notch side of filament vertical

6. Translate lamp horizontally so that reticle center bisects filament lengthwise

7. Translate lamp vertically so that reticle center is positioned at height of notch opening

8. Translate lamp along optical axis until filament is in focus

9. Rotate lamp about vertical axis so that both edges of filament are in focus

10. Translate lamp horizontally and vertically to reticle center

1 1 . Place 1/4" aperture on objective lens

12. Place mirror behind lamp alignment arrow

13. Rotate lamp about horizontal axis so that tip of arrowhead is positioned at height of notch

opening

14. Rotate lamp about vertical axis so that tip of arrowhead is positioned at notch opening

15. Repeat steps 13 and 14 until tip of arrowhead is centered at notch opening

16. Translate lamp horizontally and vertically to reticle center at height of notch

17. Repeat steps 3 to 16 for standard and test lamps

18- Set up PEP for measurements (see RTMLP2)

G:\LPManual\RTMLP6.

D12

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Ribbon Filament Lamp Operation

Written by: Charles Gibson Procedure: RTMLP7

Approved by: Date:

Revised by: Date:

Ribbon Filament Lamp Operation

BRIGHT SOURCE

BURN

ELECTROCUTION

1 . Use Kimwipe to avoid touching lamp envelope

2. Place lamp in socket

a. Check lamp polarity (center contact for screw base, longer filament support for

mogal base at positive potential)

b. Set alignment arrow or mark away from PEP

3. Go to rack of power supplies

4. Turn on digital multimeter

5. Turn on GP-IB Programmer(s) for supply(s) to be used

a. cables and programmers are numbered with corresponding power supply number

b. programmers are two channel 12 bit D/A converters

6. Check that correct cable is connected to power supply

7. Switch on power supply

8. Run lamp current monitoring program

a. Turn on computer

b. Type 2 and press [Enter] at DOS prompt to load and run lamp monitoring

program

c. Set lamp current

i. Press 1 to set power supply current

ii. Type (supply #) and press [Enter]

iii. Type (lamp current) and press [Enter]

d. Monitor lamp currents

i. Press 3

ii. Press [Esc] to return to main menu

G:\LPManual\RTMLP7.

D13

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP7: Ribbon Filament Lamp Operation

e. Turn off supply

i. Press 2

ii. Type (supply #) and press [Enter]

f. Change lamp current

i. same as (1)

g. Set multiple lamp currents

i. Press A to select power supplies to turn on

ii. Type (lamp current) and press [Enter] to select supplies to turn on

iii. Type 0 and press [Enter] to skip supply

h. Turn off all supplies

i. Press B to turn off all lamps

ii. Type OFF and press [Enter] to turn off all lamps

i. Trouble-shoot

i. Check program locking

(1) Type Ctrl [Break]

(2) Type GOTO 20, press [Enter] to return to main menu

9. Align lamps (see RTMLP6)

1 0. Use EMERGENCY TURN OFF procedure when necessary

a. Go to supply

b. Turn CURRENT knob counter clockwise to turn down lamp current

c. Turn off supply

d. Turn off GP-IB Programmer for supply

G:\LPManual\RTMLP7.

D14

Page 2
i Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Ribbon Filament Lamp Procedure

Written by: Charles Gibson Procedure: RTMLP8

Approved by: Date:

Revised by: Date:

Ribbon Filament Lamp Calibration Procedure

1 . Review calibration summary

a. Align and measure test lamp at 1700 °C

b. Measure 2300 °C to 800 °C in 100 °C steps

c. Repeat 1700 °C, 2300 °C, 1900 °C, 1500 °C, 1 100 °C, and 800 °C

2. Run general data taking program (see RTMLP 1

)

3. Align standard and test lamps (see RTMLP6))

4. Run calibration program

a. Click on "Calibrations" from Hardware.frm menu to load Rtcal.frm

b. Select "Lamps and blackbodies" button

c. Enter data filename

d. Enter test filename suffix$

i. Create test filenames from names on Software.frm

e. Select Yes and use suggested ranges (PMT high voltage and amplifier ranges are part of Rtcal.frm program)

f. Click on "Start" button

g. Enter data on Software.frm

i. Enter lamp and blackbody data

(1) Enter data for reference and test lamps

(2) Select "Use" button

(3) Enter lamp position

(4) Enter lamp name

(5) Select "Reference" button

(6) Enter lamp current (no necessary, lamp current automatically read

from lamp monitoring computer)

(7) Enter power supply number

ii. Select temperature scale

iii. Select measurement wavelength [nm]

iv. Enter number of repeats (number of test/standard measurements)

G:\LPManual\RTMLP8.

D15

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP8: Ribbon Filament Lamp Procedure

v. Enter number of readings (number of readings per DMM trigger)

vi. Select lamp type

vii. Select detector channel

h. Click on "Save Configuration" button

i. Select "Continue" button to return to Rtcal.frm

j. Enter Standard temperature in °C in input box

k. Enter Nominal radiance temperature in input box

1. Read lamp currents automatically m. Adjust test lamp current so that test lamp signal matches that indicated on

Suggestfrm

n. Wait for lamp to stabilize (5 min, 10 min, 15 min, or 20 min depending on

measurement temperature)

o. Check lamp alignment

p. Move source table to reference source and measure full scale signal

q. Move source table to dark signal position and measure dark signal

r. Move source table to test source and measure full scale signal

s. Move source table to dark signal position and measure dark signal on test source

amplifier range, if reference and test source amplifier ranges are different

t. Repeat steps r to s for each test source

u. Repeat steps p to s "number of repeats" times

v. Select next action and then select "Continue" button

i. Repeat measurement with no changes

ii. Measure with new temperature

iii. Measure with new software changes

iv. Stop measurements

w. Repeat steps k to v for each measurement point

G:\LPManual\RTMLP8.1

D16

Page 2
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP8: Ribbon Filament Lamp Procedure

5. Store calibration data in log file "CALMMDD.YY'

6. Use sample log file below:

Date 08-15-1995 Time 12:49:14 PM

File Name = CAL08 15.95

PMT Detector PMTHV= 449 NRDS = 5 Integration Time = 8.35 s Wavelength = 655.3 nm Nominal Rad Temp = 1700 °C

Name SL20 P51

Rad. Temp 1255.07 °C 1700.37 °C

Current 7.7788 A 26.960 A

Sp. Rad. 5.696E+02 1.456E+04

Ratio 1.000E+00 2.556E+01

Std. Ratio 0.01% 0.04%

Amp Range 9 8

Full Scale 1.052E+00 ±0.00% 2.685E+00 ±0.00%

1.052E+00 ±0.00% 2.683E+00 ±0.00%

1.052E+00 ±0.00% 2.684E+00 ±0.00%

Dark Sig. 1.501E-04 -8.035E-05

Mean 1.052E+00 2.684E±00

Std(Mean) 0.01% 0.04%

Range Cf. 9.9858E-02 1.0000E+00

SS Cf. 1.000E+00 1.000E+00

Corr. Mean 1.050E-01 2.684E+00

Position # 1 6

Table Pos. 37500 246000

G:\LPManual\RTMLP8.

D17

Page 3
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP8: Ribbon Filament Lamp Procedure

7. Store lamp data in test file "XXXXMMDD.YY"

8. Use sample test file below:

P510815.95

08-15-1995 12:49:14 PM

Tnom °C Tmeas °C Imeas °C Test/Standard

1700 1700.37 26.960 2.5558E+01

2300 2300.22 43.340 3.4164E+02

2200 2200.29 40.330 2.4203E+02

2100 2100.04 37.440 1.6636E+02

2000 2000.04 34.670 1.1075E+02

1900 1900.16 31.990 7.1053E+01

1800 1800.13 29.420 4.3646E+01

9. Reduce data (see RTMLP9)

G:\LPManual\RTMLP8.

D18

Page 4
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Ribbon Filament Lamp Data Reduction

Written by: Charles Gibson Procedure: RTMLP9

Approved by: Date:

Revised by: Date:

Ribbon Filament Lamp Data Reduction

1 . Print out test file 2. Look in lab notebook and make changes on printout and then edit file

3. Load Visual Basic program: c:\programs\lmpredn\Rtred.mak (do one of following)

a. Click on Rtred.mak shortcut icon

b. Double click on folder c: \programs\lmpredn\Rtred. mak using Windows Explorer

4. Run program (do one of following)

a. Press F5

b. Click on tool bar icon

c. Click on menu item "Run" then on "Start"

5. Select number of lamps to reduce

6. Enter 4 character serial number for each lamp

7. Enter data file suffix

8. Select directory that contains data file

9. Select degrees of freedom for curve fit 10. Click on "Run" button

1 1 . Print data in list box

12. Calculate mean (Tmeas) and standard deviation are calculated

13. Compare standard deviation to control limit

14. Correct lamp current to nominal temperature using following method, because measured

temperatures are different from nominal temperatures (Tnom) a. Fit data to fifth degree polynomial using least squares approximation

b. Define independent variable: Tmean = {TmeJn-\) + Tmeas(n))/2

c. Define dependent variable: M/AT= (7meas(«-l) - Imea£n))/(Tme:iS(n-\) - Tmeas(n))

d. Calculate dl/dT from fit

e. Define corrected lamp current: IC0TT = Imeas +o7/dr *(Tmm - Tmeas)

1 5 . Store reduced data in log file "REDMMDD.YY"

16. Use sample log file on next page:

G:\LPManual\RTMLP9.

D19

Page 1
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

Reducing 'C\PYRO\P5 108 15.95' 08-17-1995 11:26:56 AM

P510815.95

08-15-1995 12:49:14 PM

i nom c Tmeas °C Imeas A Test/Standard

1700 1700.37 26.96 2.5558E+01

2300 2300.22 43.34 3.4164E+02

2200 2200.29 40.33 2.4203E+02

2100 2100.04 37.44 1.6636E+02

2000 2000.04 34.67 1.1075E+02

1900 1900.16 31.99 7.1053E+01

1800 1800.13 29.42 4.3646E+01

Tnom °C Tmean °C Imeas A Std Error Limit Flag Nrpt

800 800.82 11.850 0.09 0.21 3

900 899.58 12.720 0.00 0.19 1 1000 1000.04 13.800 0.00 0.15 1 1100 1100.02 15.100 0.00 0.09 1 1200 1199.63 16.620 0.00 0.10 1

Tnom Imeas Tmeas Tmean Dell/DelT dl/dT DelT Dell Icorr °C

0800

0900

1000

1100

1200

A

11.850

12.720

13.800

15.100

16.620

°C

0800.82

0899.58

1000.04

1100.02

1199.63

°C

0850.20

0949.81

1050.03

1149.83

1249.74

0.0088

0.0108

0.0130

0.0153

0.0174

0.0079 -0.82

0.0097 0.42

0.0119 -0.04

0.0141 -0.02

0.0163 0.37

-0.007

0.004

0.000

0.000

0.006

A

11.843

12.724

13.800

15.100

16.626

G:\LPManual\RTMLP9.

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

Coefficients used to calculate d//d!T from a 5

th degree polynomial

C(0)- U.UoJ j 1 /4ooU4J 1 j / C(l)- O A AT £ CT5 "7T7'7£'7T? A/1 -Z.40J jjzj /z / /j /b-U4

C(2)- i.jo/zoyiyj /ouiob-u/

C(3)- -z. 2908398 /z3j /ojb-10

/""V A \ C(4)- 6.906464900/ 1 j4ob-14

C(5)- T A/Ci 1 OOO AAQ/C/1 A 1 f 10 - /.963z88z0yoo4U 1 b- 1

5

O AA 800 11 O A 1

1 1 .843

AAA 900 1 T A 12. /z4

1 AAA 1000 1 T OAA 13.800

1 1 AA 1 100 1 C 1 AA 1 j. 100

1200 16.626

1300 18.363

1400 20.289

1500 22.376

1600 24.599

1700 26.951

1800 29.417

1900 31.988

2000 34.669

2100 37.441

2200 40.321

2300 43.331

Data is stored in 'C:\PYRO\P510895.TXT'

Reduction of file 'C:\PYRO\P5 108 15.95 * is complete

G:\LPManual\RTMLP9.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

1 7. Save Tnom and /corT in data file "XXXXMMYY.TXT"

18. Use sample test data file below:

C:\PYRO\P510895.TXT

800 11.843

900 12.724

1000 13.800

1100 15.100

1200 16.626

1300 18.363

1400 20.289

1500 22.376

1600 24.599

1700 26.951

1800 29.417

1900 31.988

2000 34.669

2100 37.441

2200 40.321

2300 43.331

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

Compare current calibration to previous calibration

Click on "Compare calibrations" from menu

Select previous calibration filename

Select current calibration filename

Select temperature scale (°C, °F, or K)

Select international temperature scale (ITS-48, ITS-68, ITS-90)

Enter wavelength (nm) for previous data file Enter wavelength (nm) for current data file Click on "Run" button

Enter data file name "XXXXmyy.MYY"

a. Define myy: month and year of previous calibration

b. Define MYY: month and year of current calibration

Store comparison data in log file "CMPMMDD.YY"

Use sample log file on next page:

G:\LPManual\RTMLP9.Page 4

D22
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

08-17-1995 11:50:32

Previous calibration data file = 'c:\files\p510393.txt' Current calibration data file = 'c:\files\p510895.txt'

Comparing previous to current calibration 655.3nm 655.3nm WL Change Total %Change Scale Temp Old [I] New [I] New [I] dl DI/DT Corr. Temp. Change Rad. Corr. [°C] L J ITS-90 ITS-90 ITS-90 ITS-90 ITS-90 ITS-90 [°C]

[A] [A] [A] [A] [A/°C]

800 11.847 11.843 11.843 0.004 0.0078 0.00 0.51 0.51 0.98% 0.00

900 12.724 12.724 12.724 0.000 0.0096 0.00 0.00 0.00 0.00% 0.00

1000 13.799 13.800 13.800 -0.001 0.0119 0.00 -0.08 -0.08 -0.11% 0.00

1100 15.098 15.100 15.100 -0.002 0.0142 n fin -0.14 -0.14 -U. 10/0 n no u.uu 1200 16.623 16.626 16.626 -0.003 0.0164 0.00 -0.18 -0.18 -0.18% 0.00

1300 18.361 18.363 18.363 -0.002 0.0185 0.00 -0.11 -0.11 -0.10% 0.00

1400 20.287 20.289 20.289 -0.002 0.0201 0.00 -0.10 -0.10 -0.08% 0.00

1500 22.372 22.376 22.376 -0.004 0.0216 0.00 -0.18 -0.18 -0.13% 0.00

1600 24.600 24.599 24.599 0.001 0.0230 0.00 0.04 0.04 0.03% 0.00

1700 26.956 26.951 26.951 0.005 0.0242 0.00 0.21 0.21 0.12% 0.00

1800 29.423 29.417 29.417 0.006 0.0252 0.00 0.24 0.24 0.12% 0.00

1900 31.992 31.988 31.988 0.004 0.0262 0.00 0.15 0.15 0.07% 0.00

2000 34.666 34.669 34.669 -0.003 0.0272 0.00 -0.11 -0.11 -0.05% 0.00 2100 37.442 37.441 37.441 0.001 0.0283 0.00 0.04 0.04 0.01% 0.00

2200 40.329 40.321 40.321 0.008 0.0295 0.00 0.27 0.27 0.10% 0.00

2300 43.340 43.331 43.331 0.009 0.0307 0.00 0.29 0.29 0.10% 0.00

Comparison data stored in 'CMP08 17.95' Total change and %Change Radiance stored in 'P51 393.895'

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

3 1 . Use sample comparison data file below:

P51_393.895 08-17-1995 11:50:49 AM

Tempx [°C] L J dT [°C] %dL

800 0.51 0.98%

900 0.00 0.00%

1000 -0.08 -0.11%

1100 -0.14 -0.16%

1200 -0.18 -0.18%

1300 -0.11 -0.10%

1400 -0.10 -0.08%

1500 -0.18 -0.13%

1600 0.04 0.03%

1700 0.21 0.12%

1800 0.24 0.12%

1900 0.15 0.07%

2000 -0.11 -0.05%

2100 0.04 0.01%

2200 0.27 0.10%

2300 0.29 0.10%

G:\LPManual\RTMLP9.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

32. Prepare calibration summary sheet

33. A sample calibration summary sheet is below:

Radiance Temperature Lab

Calibration Summary Sheet

Today's date: December 17, 1997

NIST Test No: 844/123456-95 Use sample report: 35050c.rfl

Company: Radiometric Systems Inc

Contact: John Doe Phone: 301 123-4567

P.O.#: AB1234 dated January 1, 1995

Test number: 35050C Radiance Temperature Standard, Ribbon Filament Lamp

Test item: One General Electric Tungsten Ribbon Filament Lamp, Model # 30/T24/6,

Serial # P51

Temperatures measured: 800 °C to 2300 °C Aligned at 1700 °C

Standard(s) used: SL20 (7.7788 A, 2.093 V), (Pcos(20)=0.001 107, 12/92 TR2 p 123)

Temperature: 21 °C ± 1 °C Relative humidity: 38% ± 5%

Calibration date: 5/24/95 Measurement date(s): 5/24/95 TR3 p42

Data taking program: C:\programs\datatakn\pyro.mak|rtcal.frm 10/9/96

Calibration files: CAL0815.95, P510815.95

Data reduction program:C:\programs\lampredn\rtred.mak|lmpred.frm 5/25/95

Reduction summary: Red0525.95

Final data filename: P510895.TXT

Data analysis program:C:\programs\lampredn\rtred.mak|compare.frm 5/25/95

Reduction summary: Cmp08 17.95

Previous calibration filename: P510393.TXT

Comparison filename: P51_393.895

G:\LPManual\RTMLP9.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP9: Ribbon Filament Lamp Data Reduction

34. Enter data file name "XXXXmyy.MYY"

a. Prepare history file consisting of Microsoft EXCEL spreadsheet with plots of

temperature difference from first calibration versus nominal temperature

G:\LPManual\RTMLP9.1

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_—

Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Variable Temperature Blackbody (BB) Alignment

Written by: Charles Gibson Procedure: RTMLP10

Approved by: Date:

Revised by: Date:

Variable Temperature Blackbody (BB) Alignment

COLLISION

1. Align PEP (see RTMLP2)

2. Remove field stop

3. Remove objective lens aperture, if any

4. Level aluminum plate (<X)

5. Use fiber optic light to illuminate BB

6. Translate BB along optical axis until center partition is in focus (Z)

7. Center BB on optical axis (X and Y)

8. Turn on BB (see RTMLP1

1

)

9. Radiometrically center BB

a. Center <Y about vertical axis

b. Center X along horizontal axis

c. Repeat i and ii until centered

d. Check centering

i. Monitor BB signal on graph logger

ii. Hold card in front of BB opening

iii. Check for equal drop-offs when blocking top, bottom, left, and right

portions of BB opening

G:\LPManual\RTMLP 1 0.

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Variable Temperature Blackbody (BB) Operation

Written by: Charles Gibson Procedure: RTMLP11

Approved by: Date:

Revised by: Date:

Variable Temperature Blackbody Operation

BRIGHT SOURCE

BURN

ELECTROCUTION

1. Turn On BB

a. Open tap water valve 1/8 turn

b. Check that blue box flow rate is about 2 gpm

c. Open chilled water valves

i. Open supply valve 1/4 turn

ii. Open return valve fully

d. Press reset button on blue water switch box to select chilled water

e. Check that blue box flow rate is about 5 gpm

f. Open argon cylinder valve fully

g. Turn on argon alarm and check that it trips at 10 cfh

h. Purge BB using argon flow rate of 70 cfh

i. Cover both BB openings for 5 s with your hands

ii. Uncover one end and wait 5 s

iii. Cover both BB openings for 5 s with your hands

iv. Uncover other end and wait 5 s

i. Repeat step h 5 times

j . Reduce argon flow rate to 1 0 cfh

k. Check that BB housing is cool and that argon is flowing

1. Insert correct detector filter for initial set point

i. Filter 0, 700 °C to 1 300 °C, Low with insulation (LIN)

ii. Filter 1 , 1 300 °C to 1 800 °C, Medium (MED)

iii. Filter 2, 1 800 °C to 2500 °C, High (HI)

iv. Filter 3, 2500 °C to 3100 °C, Extra High(XH)

m. Switch control mode to [MANUAL]

n. Turn potentiometer to 0

G:\LPManual\RTMLPl 1 . 1 Page 1 D28
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP11: Variable Temperature Blackbody (BB) Operation

Press [START], [WATER ON], and [RUN] buttons

i. Note that BB does not control chilled water flow, because automatic BB

shutoff switch has been disabled

Turn potentiometer slowly until voltmeter reads between 150 VAC and 200 VAC

(sets BB below 1300 °C)

2. Operate BB

a. Run BB control program

i. Program is BBPROG.PRG in BetterBasic

ii. Enter BB at DOS prompt

iii. Enter measurement direction

(1) '0' to run high to low

(2) T to run low to high

iv. Enter set point unit

(1) 'C for °C

(2) T* for °F

v. Enter temperature range

(1) LOW

(2) LIN

(3) MED

(4) HI

(5) XH

vi. Insert correct filter and press [Enter]

b. Press [Shift S] to enter initial set point

c. Adjust potentiometer until temperature is 20 °C above set point

d. Switch control mode to [PC] to maintain set point

WARNING! DO NOT INCREASE SET POINT BY STEPS LARGER THAN 20 °C TO

REDUCE DAMAGE TO BB

e. Select new set point (set point is in °C or °F depending on set point unit selected)

i. Press [Shift S] to enter set point

ii. Use numeric keypad to increment set point

(1) Press increment key

(a) Press 7 for 100 °C

(b) Press 4 for 10 °C

(c) Press 1 for 1 °C

o.

PG:\LPManual\RTMLP 11.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP11: Variable Temperature Blackbody (BB) Operation

(d) Press 0 for 0.1 °C

(2) Press direction key to set new set point

(a) Press 8 to increase set point

(b) Press 2 to decrease set point

f. Pause program (suspending BB control) if new set point is not in current range

i. Use default set points depending on measurement direction

(1 ) Use high to low default set points

(a) Select XH for 2500 °C

(b) Select HI for 2300 °C

(c) Select MED for 1800 °C

(d) Select LOW for 1300 °C

(2) Use low to high default set points

(a) Select LOW for 800 °C

(b) Select MED for 1300 °C

(c) Select HI for 1800 °C

(d) Select XH for 2500 °C

ii. Switch control mode to [MANUAL] if new set point is not default value

iii. Loop program step 2.a.v. (see

3 . Use EMERGENCY TURN OFF procedure when necessary

a. Press [EMERGENCY STOP] button on power supply (chilled water and argon

will continue flowing)

b. Continue with steps 4.b. to 4.j. 4. Turn Off BB

a. Switch control mode to [MANUAL]

b. Turn to potentiometer to 0

c. Press [EMERGENCY STOP] button on power supply (chilled water and argon

will continue flowing)

d. Switch off main breaker on wall

e. Wait until furnace has stopped glowing

f. Close chilled water supply valve

g. Close chilled water return valve

h. Close cold water supply valve

i. Close argon cylinder valve

j . Close argon flow meter valve

G:\LPManual\RTMLP 11.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Disappearing Filament Optical Pyrometer Alignment

Written by: Charles Gibson Procedure: RTMLP12

Approved by: Date:

Revised by: Date:

Disappearing Filament Optical Pyrometer Alignment

1. Align BB (see RTMLP 10)

2. Check that objective lens and eye piece are clean

3. Check batteries

4. Zero galvanometer

5. Use post with magnetic base, height adjustment, and angle bracket to mount pyrometer

6. Position post and level angle bracket mounting surface

7. Mount pyrometer to angle bracket

COLLISION

8. Use joystick to move BB to test pyrometer position

9. Use fiber optic light to illuminate BB

10. Set pyrometer at measuring distance from BB center partition

a. Use distance of 30.2 cm from center partition to end of graphite extension tube

b. Measure distance from front surface of objective lens holder to extension tube (for

1 m, distance is 69.8 cm)

1 1 . Adjust pyrometer eye piece to focus on illuminated lamp filament

12. Focus pyrometer on center partition

13. Adjust pyrometer and/or move BB so that pyrometer views down center of BB cavity

14. Check distance

15. Adjust pyrometer and/or move BB so that pyrometer views down center of BB cavity

16. Record table position

1 7. Repeat for other test pyrometers

G:\LPManual\RTMLP12.1 Page 1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Radiation Thermometer (RT) Alignment

Written by:

Approved by:

Revised by:

Charles Gibson Procedure: RTMLP13

Date:

Date:

Radiation Thermometer (RT) Alignment

1. Align BB (see RTMLP10)

2. Check that objective lens and eye piece are clean

3. Use post with magnetic base, height adjustment, and angle bracket to mount RT

4. Position post and level angle bracket mounting surface

5. Mount RT to angle bracket

COLLISION

6. Use joystick to move BB to test RT position

7. Use fiber optic light to illuminate BB

8. Set RT at measuring distance from BB center partition

a. Use distance of 30.2 cm from center partition to end of graphite extension tube

b. Measure distance from front surface of objective lens holder to extension tube (for

1 m, distance is 69.8 cm)

c. Measure distance from alignment mark to extension tube for Land Cyclops RT

(for 1 m, distance is 69.8 cm)

9. Adjust RT eye piece to operator's eye

1 0. Focus RT on center partition

1 1 . Adjust RT and/or move BB so that RT views down center of BB cavity

12. Check distance

13. Adjust RT and/or move BB so that RT views down center of BB cavity

14. Record table position

15. Repeat steps 2 to 14 for each test RT

1 6. Turn on BB (see RTMLP1

1

)

17. Check centering of each test RT

a. Monitor RT signal on graph logger or look at RT display panel

b. Hold card in front of BB opening

c. Check for equal drop-offs when blocking top, bottom, left, and right portions of

BB opening

G:\LPManual\RTMLP13.1 Page 1 D32
Optical Technology Division (844)

1 Radiance Temperature Measurements Laboratory Procedure

Radiation Thermometer (Optical Pyrometer)

Calibration Procedure

Written by: Charles Gibson Procedure: RTMLP14

Approved by: Date:

Revised by: Dale:

!

Radiation Thermometer (Optical Pyrometer) Calibration Procedure

1 . Review calibration summary

a. Align standard lamp, BB, and test RTS

b. Measure from 2700 °C to 800 °C in 100 °C steps

c. Repeat 2300 °C, 1900 °C, 1500 °C, 1300 °C, 1 100 °C, and 800 °C

2. Run general data taking program (see RTMLP1)

3. Align standard lamp (see RTMLP6)

4. Align BB (see RTMLP 10)

5. Align RTS (see RTMLP 13)

6. Run calibration program

a. Click on "Calibrations" from Hardware.frm menu to load Rtcal.frm

b. Select "Radiation thermometer" button

c. Enter data filename

d. Enter test filename suffix$

i. Create test filenames from names on Software.frm

e. Select Yes and use suggested ranges (PMT high voltage and amplifier ranges are

part of Rtcal.frm program)

f. Click on "Start" button

g. Enter data on Software.frm

i. Enter lamp and blackbody data

(1) Enter data for reference and BB

(2) Select "Use" button

(3) Enter lamp position

(4) Enter lamp name

(5) Select "Reference" button

(6) Enter lamp current (not necessary because lamp currents are automatically read from lamp monitoring computer)

(7) Enter power supply number

G:\LPManual\RTMLP14.

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP14: Radiation Thermometer (Optical Pyrometer)

Calibration Procedure

ii. Enter radiation thermometer data

(1) Enter data for check standard and test RTS

(2) Select "Use" button

(3) Enter RT name

(4) Enter source table position

(5) Enter digital multimeter channel to read signal

(6) Enter RT type (0 for optical pyrometers and R for radiation

thermometers)

(7) Enter output type (P for panel or scale, D for digital, A for analog)

(8) Select instrument wavelength (nm)

iii. Select temperature scale

iv. Select measurement wavelength [nm]

v. Enter number of repeats (number of test/standard measurements)

vi. Enter number of readings (number of readings per DMM trigger)

vii. Select lamp type

viii. Select detector channel

h. Click on "Save Configuration" button

i. Select "Continue" button to return to Rtcal.frm

j. Enter Standard temperature in °C in input box

k. Enter Nominal radiance temperature in input box

1. Read lamp currents automatically m. Enter BB set point

n. Wait 5 min for BB to stabilize

o. Move source table to reference source and measure full scale signal

p. Move source table to dark signal position and measure dark signal

q. Move source table to BB and measure full scale signal

r. Move source table to dark signal position and measure dark signal on BB

amplifier range if reference and BB amplifier ranges are different

s. Repeat steps o to r "number of repeats" times

t. Enter emissivity correction for test RT wavelength

i. Enter 0 for 655.3 nm

ii. Enter 1 for 900 nm

iii. Enter 2 for 1 000 nm

iv. Enter 3 for true temperature

G:\LPManual\RTMLP 14.1 Page 2

D34
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP14: Radiation Thermometer (Optical Pyrometer)

Calibration Procedure

u. Move BB in front of each RT and take reading

i. Read RTs with digital outputs 3 times

ii. Read RTs with analog outputs 3 times

iii. Enter display value for RTs with digital display panels

iv. Read OPs matching from bright to dark and then from dark to bright

(1) Enter scale value or press [Enter] to read output signal

(2) Read 2 sets

v. Select next action and then select "Continue" button

i. Repeat measurement with no changes

ii. Measure with new temperature

iii. Measure with new software changes

iv. Stop measurements

w. Repeat xxii for each measurement point

7. Store calibration data in log file "CALMMDD.YY"

8. Use sample log file on next page:

G:\LPManual\RTMLP 14.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP14: Radiation Thermometer (Optical Pyrometer)

Calibration —Procedure —

b MM—

Date 12-13- 1996 Time 9:48:10 AM

File Name = CAL1213.96

PMT Detector PMT HV - 449 V NRDS = 5 Integration Time = 8.35 s Wavelength = 655.3 nm Nominal Rad Temp = 1800 °C

Name SL20 TGBB

Rad. Temp 1254.96 °C 1799.01 °C

Current 7.7788 A

Sp. Rad. 5.690E+02 2.472E+04

Ratio 1.000E+00 4.344E+01

Std. Ratio 0.06% 0.05%

Amp Range 9 8

Full Scale 1.016E+00 ±0.00% 4.411E+00 ±0.00%

1.016E+00 ±0.00% 4.411E+00 ±0.01%

1.015E+00 ±0.00% 4.410E±00 ±0.01%

Dark Sig. 1.510E-04 -1.166E-04

Mean 1.015E+00 4.411E+00

Std(Mean) 0.04% 0.01%

Range Cf. 9.9858E-02 1.0000E+00

SS Cf. 1.000E+00 9.987E-01

Corr. Mean 1.014E-01 4.405E+00

Position # 1 3

Table Pos. 37500 127500

Position CY52 TEST PYRO # 1 Reading # 1 1804 °C 0.0 °C

Mean = 1804.0 °C STD = 0.0 °C

Temperature Set for THERMOGAGE - 1800 °C

Measured Temperature at 655.3 nm == 1799.01 °C

Calculated Temperature at 655.3 nm = 1799.01 °C

Mean 1804.0 °C

Test Std 0.0 °C

Test Corr. -6.0 °C

G:\LPManual\RTMLP14.1 Page 4

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP14: Radiation Thermometer (Optical Pyrometer)

Calibration Procedure

9. Store RT data in test file "XXXXMMDD.YY"

10. Use sample test data file below:

c:\PYRO\CY521213.96

12-13-1996 9:59:06 AM

Standard used is SL20 at 1254.96 °C

Temperature in °C

Temperature measured at 655.3 nm Temperature calculated at 1000 °C

Tnom Tbb Tcorr CY52 Std Corr

1800 1799.01 1797.98 1804.0 0.0 -6.0

1700 1699.18 1698.26 1704.5 0.0 -6.2

1600 1599.47 1598.64 1603.0 0.0 -4.4

1500 1499.31 1498.56 1502.0 0.0 -3.4

1400 1399.24 1398.57 1401.0 0.0 -2.4

1300 1299.30 1298.71 1302.0 0.0 -3.3

1200 1199.36 1198.85 1201.0 0.0 -2.2

1100 1099.34 1098.89 1100.5 0.0 -1.6

1100 1099.25 1098.80 1100.5 0.0 -1.7

1000 999.15 998.76 1000.0 0.0 -1.2

1 1 . Reduce data (see RTMLP 1 5)

G:\LPManual\RTMLP 14.1

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Radiation Thermometer (RT) Data Reduction

Written by: Charles Gibson

Approved by:

Revised by:

Procedure: RTMLP15

Date:

Date:

Radiation Thermometer (RT) Data Reduction

1 . Print out test file for RT check standard

a. Verify that RT check standard values are within uncertainty

2. Print out test file for BB RT check standard

a. Verify that BB RT check standard values are within uncertainty

3. Print out test files 4. Look in lab notebook and document any changes on print out and then edit file

5. Load EXCEL and open test file

6. Separate data by range or filter

7. Sort data

8. Calculate mean and standard deviation of repeats

9. Plot data

10. Save in data file "XXXXMMYY.XLS"

1 1 . Use sample data file below:

TEST1096.XLS : 11/7/96

c:\PYRO\TEST1007.96

Tnom Tbb Tcorr TEST Std Corr Corr Mean Corr Std Filter °C °C °C °C °C °C °C °C

800 799.10 798.83 801 0 -2.2 -2.5 0.4 Clear

800 800.58 800.30 803 0 -2.7 900 899.04 898.71 900.5 0 -1.8 1000 999.13 998.74 1000 0 -1.3 1100 1099.19 1098.74 1100 0 -1.3 -1.2 0.2

1100 1100.48 1100.03 1101 0 -1.0 1200 1199.32 1198.80 1200 0 -1.2

12. Use, for repeats, values of blackbody temperature (Tcon), test RT reading (TEST), and test RT correction (Corr) that best represents mean of repeats so that actual reading is reported

1 3 . Save data in text file (tab delimited) "XXXXMMYY.TXT"

G:\LPManual\RTMLP 15.1 Page 1 D38
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP15: Radiation Thermometer (RT) Data Reduction

14. Use sample file below:

Testl096.TXT 11/4/96

Tnom Tcorr TEST Corr Filter

[°C] E°C] [°C] [°C] Clear

800 800.3 803 -2.7

900 898.7 900.5 -1.8

1000 998.7 1000 -1.3

1100 1098.7 1100 -1.3

1200 1198.8 1200 -1.2

15. Prepare calibration summary sheet

16. Use sample calibration summary sheet on next page:

G:\LPManual\RTMLP 15.1

D39

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Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP15: Radiation Thermometer (RT) Data Reduction

Radiance Temperature Lab

Calibration Summary Sheet

Today's date: December 17, 1997

NIST Test No: 844/123456-95 Use sample report: 35070sdc.lum

Company: Radiometric Systems Inc

Contact: Joe Calibration Phone: 301 123-4567

P.OJ: AB1234 dated January 1, 1995

Test number: 35070S Special Test of Radiation Thermometer

Test item: One Minolta-Land Infrared Thermometer, Model # Cyclops 52, Serial # 0000000

Temperatures measured: 800 °C to 2500 °C

800 °C to 1200 °C with clear filter

1 100 °C to 2500 °C with dark filter

Standard(s) used: SL20 (7.7788 A / 2.093 V ), (Pcos(20)=0.001 107, 12/92 TR2 p 123)

Land Cyclops 52 pyrometer, Serial no.: 202681

Thermogage 7000-1 pyrometer, Serial no.: 5127

Temperature: 21 °C ± 1 °C Relative humidity: 38% ± 5%

Calibration date: 2/16/96 Measurement date(s):2/15-16/96 TR3 p79

Data taking program: C:\programs\Lmpredn\pyro.mak|rtcal.frm 10/9/96

Calibration files: Call007.96, Testl007.96 Tgbbl007.96

Data reduction program: Excel 7.0

Data reduction file: Testl096.xls Final data file: Testl096.txt

G:\LPManual\RTMLP15.1 Page 3

Wavelength = 1000 nm

Target size: 5.6 mm

Distance: 100 cm from alignment mark

Focus: 1 meterClear and dark lenses (sn LI)

D40
Optical Technology Division (844)

Radiance Temperature Measurements Laboratory Procedure

Procedure RTMLP15: Radiation Thermometer (RT) Data Reduction

i

17. Print out test file for RT check standard

a. Prepare history file consisting of Microsoft EXCEL spreadsheet with plots of

temperature difference from first calibration versus nominal temperature

G:\LPManual\RTMLP 15.1

D41

Page 4

Appendix E: How to Request Radiance Temperature Measurement Services

1. Prepare a purchase order with the following:

a. Company name and address

b. Contact person's name and phone number.

c. Billing address

d. Service ID number requested (include range and points)

e. Test fee

f. Address to ship test item

g. Return shipping instructions (prepay and add, COD, charge to account with shipper)

i. the test fee does not include shipping costs

ii. customers are responsible for all shipping costs

iii. If no instructions are given, NIST will return the test item by common carrier, collect,

and uninsured.

2. Send the purchase order to: National Institute of Standards and Technology

Calibration Program

Building 820, Room 232

Gaithersburg, MD 20899-0001

Tel.: (301) 975-2002

FAX: (301) 869-3548

E-mail: calibrations@enh.nist.gov

3. Send the test item(s) to: Charles Gibson

NIST

Building 221 / Room B208

Gaithersburg, MD 20899-0001

Tel.: (301)975-2329

FAX: (301)869-5700

E-mail: cgibson@nist.gov

WWW: http://physics.nist.gov/Divisions/Div844/staff/Gp3/gibson.html

Radiance temperature calibrations are performed in February, May, August, and November.

Requests for calibration services are scheduled after the receipt of a purchase order.

NIST policy requires prepayment of all calibration services performed for non-U.S.

organizations. Please contact the Calibration Program office to arrange payment.

E1

4U.S. GOVERNMENT PRINTING OFFICE: 1998-433-235/93205



THE SP 250 SERIES ON NIST MEASUREMENT SERVICES*

SP 250-1 Spectral Radiance Calibrations PB871 79883

SP 250-2 Far Ultraviolet Detector Standards PB87227609

SP 250-3 Radiometric Standards in the Vacuum

Ultraviolet PB87227625

SP 250-4 Fricke Dosimetry in High-Energy Electron Beams

PB881 10374 SP 250-5 Alpha-Particle Calibrations PB881 68620

SP 250-6 Regular Spectral Transmittance PB881 08550

SP 250-7 Radiance Temperature Calibrations PB881 23674

SP 250-8 Spectral Reflectance PB881 09905

SP 250-9 Calibration of Beta-Particle-Emitting

Ophthalmic Applicators

PB881 08535

SP 250-10 Radioactivity Calibrations with the "4ir" Gamma Ionization Chamber and Other

Radioactivity Calibration Capabilities

PB881 23708

SP 250-1 1 Dosimetry for High Dose Applications

PB88201587

SP 250-12 Neutron Personnel Dosimetry

PB87227617

SP 250-13 Activation Foil Irradiation with Californium

Fission Sources PB882 17443 SP 250-14 Activation Foil Irradiation by Reactor Cavity

Fission Sources PB88217435

SP 250-15 Photometric Calibrations PB881 53747

SP 250-16 Calibration of X-Ray and Gamma-Ray

Measuring Instruments PB88211826

SP 250-17 The NBS Photodetector Spectral Response

Calibration Transfer Program

PB88201595

SP 250-18 Neutron Source Strength Calibrations PB88211818

SP 250-19 Calibration of Gamma-Ray-Emitting

Brachytherapy Sources PB891 93858

SP 250-20 Spectral Irradiance Calibrations PB881 23781

SP 250-21 Calibration of Beta-Particle Radiation Instrumentation PB88201579

SP 250-22 Platinum Resistance Thermometer

Calibrations PB881 38367

SP 250-23 Liquid-in-Glass Thermometer

Calibration Service PB891 28888

SP 250-24 Standard Cell Calibrations PB881 23690

SP 250-25 Calibration Service for Inductive Voltage Dividers SP 250-26 NBS Phase Angle Calibration Services PB88225636

SP 250-27 AC-DC Difference Calibrations PB892222616

SP 250-28 Solid-State DC Voltage Standard Calibrations PB881 68703

SP 250-29 Traceable Frequency Calibrations PB881 68364

SP 250-30 GOES Satellite Time Code Dissemination:

Description and Operation

PB881 68760

SP 250-31 Mass Calibrations PB89 153894

SP 250-32 A Calibration Service for 30 MHz

Attenuation and Phase Shift PB88238324

SP 250-33 A Calibration Service for Voltage Transformers and High-Voltage Capacitors

PB882252903

SP 250-34 High Vacuum Standard and Its Use

PB891 93841 SP 250-35 The Calibration of Thermocouples

and Thermocouple Materials PB89209340

SP 250-36 A Calibration Service for Current Transformers PB91216770

SP 250-37 Photometric Calibrations PB971 48472

SP 250-38 NIST Leak Calibration Service PB921 49772

SP 250-39 NIST Pressure Calibration Service PB941 64043

SP 250-40 Absorbed-Dose Calibration of Ionization Chambers in a

60Co Gamma-Ray Beam

SN003-003-03034-1 $2.00

* Entries containing a stock number (SN003-003-) and price can be purchased from the Superintendent of Documents, U.S. Government

Printing Office, Washington, DC 20402. GPO will accept checks, money orders, VISA, and MasterCard. For more infomation, or to place an order, call (202) 512-1800. Be sure to cite the stock number on all orders.

Entries containing PB numbers can be purchased from the National Technical Information Service, Springfield, VA 22161 . NTIS will accept

American Express in addition to the payment methods listed for GPO. For more information call (703)487-4650; to place an order call (800) 553-6487. Fax: (703) 321-8547. Be sure to cite the PB number on all orders.

Entries without stock or PB numbers are in preparation.
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