NATIONAL BUREAU OF STANDARDS REPORT

3077

LUMINOSITY FILTER AND THERMOPILE

FOR

A PHYSICAL PHOTOMETER

by

Ray P. Teele

Marion A. Belknap

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks* Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infrared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Surface Cheqiistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance Electronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

Missile Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense.

© Office of Basic Instrumentation © Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT MBS REPORT

0201-30-2322 January 29 , 19 ^ 3077

LUMINOSITY FILTER AND THERMOPILE

FOR

A PHYSICAL PHOTOMETER

by

Ray P. Teele

Marion A. Belknap

Photometry and Colorimetry Section

Optics and Metrology Division

Sponsored by

Signal Corps Engineering Laboratories

Fort Monmouth, New Jersey

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprlnl

unless permission isobti 25 , D, C, Such permlss

cal ly prepared If that ;

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

art, Is prohibited

irds, Washington

has been speclfiI for Its own use,

LUMINOSITY FILTER AND THERMOPILE

FOR

A PHYSICAL PHOTOMETER

by

Ray P. Teele

Marion A, Belknap

This report describes development

work on a luminosity filter and

thermopile for a physical photometer in accordance with correspondence and Signal Corps Supply Agency

purchase order 15618-PH-53-92 ( 11419 )

National Bureau of Standards test

number G-12kl9 covers this work.

1. MATERIAL

The Signal Corps furnished the following materials:

2 absorption cells

2 uranium glass filters

2 infrared-absorbing glass filters

1 thermopile, Eppley #2177

The National Bureau of Standards supplied the following materials:

1 liter of the liquid component.

(one absorption cell was filled

and the remainder sealed in a bottle

1 circuit diagram

3 calibrated standard lamps

The measured glass filters and the thermopile have

been marked G-12kl9.

2. MEASUREMENTS

The National Bureau of Standards made spec trophotometric measurements on one of each type of glass, determined

the composition of a liquid component which, used with the

Wo glass filters, would duplicate closely the luminosity

curve of the CIE standard observer. Three standard lamps

calibrated for luminous intensity in a specified direction

were supplied by the NB3. The response of the thermopile

when used with the luminosity filter was determined.
2.1 Spectrophotometr ic Data

The glass filters were measured on the General Electric

and Beckman quartz photoelectric spectrophotometer s . Measurements on the General Electric recording spectrophotometer

were made with an effective spectral band of approximately

10 millimicrons of spectrum from kOO to 750 millimicrons and

20 millimicrons of spectrum ; rom 730 to 1300 millimicrons.

A comparable set of measurements was made on the Beckman spectrophotometer, but with much narrower slit widths. A hydrogen

source was used for measurements below kOO millimicrons to the

extinction point in the ultraviolet for each filter. The infrared absorbing glass was measured in the infrared to 1300

millimicrons, with use of a stray energy filter above 9&0

millimicrons

The marked absorption cell was measured on the General

Electric recording spectrophotometer only at wavelengths of

kOO mfz and above because the strong absorption of the other

components of the complete filter makes unimportant the values for the cell below kOO mjj,. Repeat measurements were made

with the cell reversed in the sample compartment.

Values obtained at each 10 millimicron interval, corrected for wavelength, zero, and 100 percent errors, are

given in Table 1.

2.2 Photometric Data

The three standard lamps were supplied by the National

Bureau of Standards and their luminous intensity was measured by means of a calibrated . physical photometer. The

physical photometer is calibrated at periodic intervals

against the basic lamp standards. This photometer, consisting of a thermopile and luminosity filter, is a modified form of the one described in NBS J« Research 2_7, 217

(September, 19kl) RPlkl5.

The lamps were standardized while burning base down.

The orientation was such that the plane containing the two

lines etched on opposite sides of the bulb was parallel to

the photometer axis, the line having the etched circle being

turned away from the photometer. A diaphragm having an opening 2 1/2 centimeters high and 9 1/2 centimeters wide,

centered with respect to the filament and located k 1/2

centimeters from the center of the socket, was placed between the lamp and the photometer. The photometric distance was 1 meter. With the voltage held constant at the

designated value, readings were taken of current and luminous intensity. The measurements were made in the order

of the designated lamp numbers, the lowest lamp number being

taken first. Three such sets of measurements were taken,
- 3

-

the order of taking the readings being reversed in the

second set and the results given in Table 2 are the

averages of the 3 sets.

2.3 Thermopile Calibration

The luminosity filter was mounted immediately in

front of the thermopile and the response in microvolts

determined by using standard lamps. Corrections were

made for che change in optical path caused by the complete luminosity filter and for the distance between the

receiving surface and the cover glass. These corrections

are of opposite sign. The total correction amounts to

1.13 centimeters and must be subtracted from the distance between the cover glass and source in determining the effective photometric distance when using the

complete physical photometer. The receiving surface is

0.50 centimeter behind the cover glass. The calibration data for the luminosity filter and thermopile used

together are given below in Section 3, Re suits, under

3.3

Response of Thermopile.

2.4 The Luminosity Filter

The complete luminosity filter consists of an

infrared absorbing glass, a uranium glass, and the

solution component used in the absorption cell of 5.00

centimeters length. The infrared absorbing glass is

placed on the source side to reduce the heating effect

of the radiant flux on the other components, while the

uranium glass is placed on the thermopile side to minimize any fluorescence caused by radiant flux transmitted

by the infrared absorbing glass and the solution component in the near ultraviolet range of the spectrum.

The composition of the solution to be used with

the two glass components was determined from the data

for copper sulfate and cobalt ammonium sulfate given

in previous publications of the Bureau and from unpublished data for tiie potassium dichromate. The

1

~~ ~ ~ ' Filters for the Reproduction of Sunlight and Daylight

and the Determination of Color Temperature, Raymond

Davis and K. S. Gibson. Miscellaneous Publication,

Bureau of Standards, No. lib (1931).

2

Spectral Energy Distribution of the International

Commission on Illumination Light Sources A, B, and

C, Raymond Davis, K. S. Gibson, G. W. Haupt, Journal

of Research of the National Bureau of Standards,

Vol. 50, No. 1, January 1953, RP2384.
solution component is made up as follows:

Copper sulfate (CuSO^ . 5 E2

O)

Cobalt ammonium sulphate

( C o3 oi

f ( NII

lf ) l+SO^. • 0H.0 0

Potassium Dichrornate (K^jC^Oy)

Sulfuric acid (1.835 sp5g.)

Distilled w ater to make 1 liter of

17.00 grams

2.10 grams

. 140 grams

10.00 cc

solution

3 . RESULTS

3.1 Luminosity Filter

The measured values of transmittance for the two

glass components and the absorption cell are given in the

second, third and fourth columns of Table 1. The fifth

column gives the calculated relative transmittance of

the complete luminosity filter, and the CIS luminosity

values appear in the last column of the Table. The

values from column five are plotted in Figure I where

the solid line is the CIS luminosity curve.

Table 1. Spectral Transmittance of Luminosity Filter.

Transmittance

Cell with Infrared

Wavelength in distilled absorbing Uranium

millimicrons water glass glass

C IE

Luminosity luminosity

filter curve

Relative to 555 m/t

270 not rneas- 0.000 0.000 0.000 0.000

280 ured below .001 .000 .000 .000

290 2

1"

j- 00 1 .005 .000 .000 .000

300 .022 .000 .000 .000

310 — .076 .000 .000 .000

320 .,174 .000 .000 .000

330 .305 .000 .000 .000

3*+0 .44 .000 .000 .000

350 — _ .56 .001 .000 .000

360 . 66 .020 .000 .000

370 - - .735 .110 .000 .000

380 .785 .145 .00009 .000

390 .809 .079 .0004 .000

400 0.910 .813 .021 .0012 .0004

410 .910 .812 .010 .0013 .0012

420 .910 .808 .013 .0021 .0040

430 .911 .811 .039 .0058 .Olio

440 .912 .815 .127 .018 .023
- 5 -

450 .912 .817

460 .913 .812 b?0 .913 .821

480 .914 .830

490 .914 .833

500 .914 .840

510 .914 .838

520 .914 .830

530 .915 . 826

54o .915 .829

550 .915 .83 5

560 .915 .832

570 .914 .822

580 .913 .810

590 .911 .793

600 .908 .774

610 .905 .751

620 .905 .724

630 .905 .692

640 .904 . 660

650 .903 .628

660 .902 .594

670 .901 .557

680 .900 .521

690 .898 .478

700 .893 .436

710 .882 .395 720 .864 .3 56

730 .832 .321

740 . 308 .285

750 .802 .250

760 .802 .220

770 .804 .192

780 .810 .165

790 .818 .140

300 .826 .119

810 .330 .100

820 .823 .084

830 .799 .069

340 .773 .056

.245 .037 .038

.320 .059 .060

.407 .105 .091

.399 .148 .139

.402 .211 .208

.47 .31° .323

.62 .492 .503

.78 .707 .710

.84 .849 .862

.859 .942 .95*+

.867 .996 .995

.872 .998 .995

.874 .950 .952

.876 .868 .870

.879 .757 .757

.883 .634 .631

.887 .505 .503

.890 .387 + .381

.892 .275 .265

.894 .183 .175

.896 .113 .107

.898 . 066 .061

.900 .035 .032

.903 .013 .017

.905 .0087 .0082

.907 .0041 .0041

.903 .0019 .0021

.903 .00092 .00105

.903 .00045 .00052

.907 .00023 .00025

.907 .00012 .00012

.908 .00007 .00006

.909

.907

.904

.900

.898

.896

.896

.896
- 6 -

850 .754 o045 0898

860 .744 .037 .900

870 .735 .029 .901

880 .720 . 022 .900

890 .704 .018 0899

900 .682 .015 .897

910 .653 .012 .895

920 .602 .009 .893

930 .508 ,008 .892

940 .378 .007 .893

950 .234 0OO6 . 896

960 .005 .898

970 .004 .902

980 .003 .906

990 .002 .909

1000 .001 .911

1010 .000 .912

1020 .000 .914

1030 .000 .916

1040 .000 .917

1050 .000 .917

1060 .000 .917

1070 .000 .917

1080 .000 .917

1090 .000

1100 .000

to .000

1300 .000

3,2 Values for Standard Lamps

The values for the standard lamps when aligned and

diaphragmed as described above in Section 2„ Measurements,

under 2,2, Photometric Data, are given in Table 2 0 Table 2. Values for Standard Lamps

Lamp Number Volts

( set)

Amperes Candles in Specified Direction

NBS2882

NBS2883

NBS2884

105.00 3o985

105.00 3.985

105.00 4.115

975

991

1015

The values of candlepower are estimated to be uncertain by less than 3/*+ percent.
- 7

-

3.3 Response of Thermopile

With the luminosity filter immediately in front of

the thermopile the response was found to be .00229 microvolts per incident meter candle.

h. MEASURING CIRCUIT

A measuring circuit suitable for use with the thermopile was described in a paper presented at the Fall 1973

meeting of the Optical Society of America. A copy of the

manuscript is attached and is considered to be part of

this report but is not released for publication at this

t inis •




t

fr


THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project

or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.00). Information on calibration services and fees can be

found in NBS Circular 483, Testing by the National Bureau of Standards (25 cents). Both are

available from the Government Printing Office. Inquiries regarding the Bureau’s reports and

puhlications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.
NBS