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.
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)