Bidirectional Reflectance Measurements of Low-Reflectivity Optical Coating Z302

Abstract

Black coatings essentially absorb incident light at all wavelengths from all directions. They are used when minimal reflection or maximum absorption is desired and therefore are effective in applications that require control of stray light. Our motivation stems from the use of black coating Lord Aeroglaze® Z302 in aerospace and remote sensing applications and the desire to support the development of bidirectional spectral models that can be used successfully to predict the performance of optical instruments such as telescopes. The bidirectional reflectance distribution function (BRDF) is an indispensable parameter in the optical characterization of such coatings. The current effort involves investigation of the BRDF of the commercial black coating Aeroglaze® Z302. An automated goniometer reflectometer has been designed, fabricated and successfully used for performing the BRDF measurements of Z302 at visible and ultraviolet wavelengths and at both polarizations. The current contribution involves study of Z302 samples prepared at different thicknesses and by different methods, which provides insight about influence of surface roughness on BRDF of Z302.