Normal incidence, specular reflectance spectra of three samples of optical black coatings have been measured in 10 filter passbands at effective wavelengths between 12 and 700 μm. Strong absorption, due to amorphous silicate material in the coatings, is found in the 15-50 μm region of each spectrum. Reflecting-layer model calculations are fitted by a non-linear least-squares routine to the spectra at wavelengths beyond the absorption band to determine far-infrared optical parameters. It is found that, with a similar wavelength dependence, the absorption coefficient of a new black coating (ECP 2200) made by the Minnesota Mining and Manufacturing Company (3M) is less than 1/10 that of the discontinued coating, 3M Black Velvet Nextel. It is also shown that the extinction effect of a very rough substrate is negligible compared with the effects of increased upper surface roughness and coating thickness attendant upon fully covering a very rough substrate.

Date Published: 4 October 1983
PDF: 6 pages
Proc. SPIE 0384, Generation, Measurement and Control of Stray Radiation III, (4 October 1983); doi: 10.1117/12.934936

Published in SPIE Proceedings Vol. 0384:
Generation, Measurement and Control of Stray Radiation III
Robert P. Breault, Editor(s)