John T. Agnew and Richmond B. McQuistan, "Experiments Concerning Infrared Diffuse Reflectance Standards in the Range 0.8 to 20.0 Microns," J. Opt. Soc. Am. 43, 999-1007 (1953)
Goniometric measurements of the diffuse reflectance of infrared radiation have been made on 32 samples of 20 different materials. For the most part the materials were finely divided powders of metallic and semimetallic elements and compounds, with a firmly packed surface presented to the radiation. A globar source operating at 1330°K was used, and the reflectance characteristics of the materials to radiation of wavelengths greater or less than 4.0 microns were studied by means of a quartz filter.
Arbitrary comparison factors have been developed by means of which the diffuse reflectance of the materials can be rated with respect to cosine law distribution and spectral reflectivity. The measurements show that of the materials tested, sulfur, sodium chloride, selenium, and aluminum have the most favorable characteristics. Several other interesting phenomena of more academic interest which were observed in the experimentation are discussed.
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Actually 0.432=fp, where the subscript p refers to the unique case of a polished mirror; as distinguished from fs, where the subscript s refers to any given material.
Table II
Size of openings in sizing screens used to screen materials.
Screen number
Size of opening in inches
28
0.0232
35
0.0164
48
0.0116
65
0.0082
100
0.0058
200
0.0029
Table III
Materials tested other than those listed in Table I.
Material
Physical condition
Aluminum
28–35
Saw filings
Brass
28–35
Glass
28–48
Plate glass ground in mortar and pestle
Glass
48–100
NaCl
28
Single crystal ground in mortar and pestle
NaCl
28–48
NaCl
48–100
Pb(O)
28–35
Globular pellets
Tin
28–35
Approximately spherical pellets
Tin
28–200
Table IV
Comparison of diffuse reflectance of materials investigated.
For these substances the value of fr was assumed to be the same as for the finely ground material of the same species for which quartz measurements were taken.
Numbers in parentheses indicate the relative position of the 22 samples for which quartz measurements were taken; sulfur being the best and antimony the worst.
Tables (4)
Table I
Materials investigated, their physical condition, and the fraction of radiation at wavelengths>4.0μ as a function of observation angle.
Actually 0.432=fp, where the subscript p refers to the unique case of a polished mirror; as distinguished from fs, where the subscript s refers to any given material.
Table II
Size of openings in sizing screens used to screen materials.
Screen number
Size of opening in inches
28
0.0232
35
0.0164
48
0.0116
65
0.0082
100
0.0058
200
0.0029
Table III
Materials tested other than those listed in Table I.
Material
Physical condition
Aluminum
28–35
Saw filings
Brass
28–35
Glass
28–48
Plate glass ground in mortar and pestle
Glass
48–100
NaCl
28
Single crystal ground in mortar and pestle
NaCl
28–48
NaCl
48–100
Pb(O)
28–35
Globular pellets
Tin
28–35
Approximately spherical pellets
Tin
28–200
Table IV
Comparison of diffuse reflectance of materials investigated.
For these substances the value of fr was assumed to be the same as for the finely ground material of the same species for which quartz measurements were taken.
Numbers in parentheses indicate the relative position of the 22 samples for which quartz measurements were taken; sulfur being the best and antimony the worst.