Quantifying the appearance of a surface is an important aspect in quality control. Becauseobjects at room temperature emit negligible amounts of radiation into the visible spectrum, aspectsof their appearance may be quantified using reflected light. Therefore, the appearance of opaquesurfaces may be quantified using measurements of the spectral, bidirectional reflectivity. However,measuring the spectral, bidirectional reflectivity of even one point at every set of incident andreflected directions is a time intensive process that is infeasible for quality control.The objective of this work was to determine whether a limited number of spectral, bidirectionalreflectance measurements may be used to characterize the appearance of an opaque surfaceat room temperatures. The results presented in this thesis demonstrate that measurements of thespectral bidirectional reflectivity in the visible spectrum at four sets of specular reflections - 20°,45°, 60°, and 85° - with a resolution of 5 nm may be used to quantify the appearance of an opaquesurface at room temperature. These measurements are converted into parameters called the bidirectionalreflectance appearance parameters (BRAPs). These BRAPs include L*, a*, b* (whichdefine the color of the surface), G20, G60, G85 (which define the gloss of the surface), and H(which describes the haze of the surface). It is shown that surfaces which appear similar havesimilar BRAPs and surfaces which appear different have different BRAPs.

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. / Master of Science / When light falls on different materials it undergoes various phenomenon such as reflection, refraction, absorption and scattering. The amount of each phenomenon varies with the optical nature of a material as well as the wavelength and direction of the light. Therefore, understanding the optical properties of materials at various wavelengths of light is necessary for effectively using those materialsin specific applications which require light to be efficiently reflected or absorbed. This research studies an optical property known as Bidirectional Reflectance Distribution Function (BRDF) of a black coating called Lord Aeroglaze Z302. Black coatings are materials that ideally absorb almost all light that falls on them irrespective of the light’s direction and wavelength. They are used in applications where maximum absorption of light is required. One such application which relates to the motivation for this research is absorbing unwanted light in instruments used in space such as telescopes and radiometers. Z302 is used in the Clouds and the Earth’s Radiant Energy System (CERES) instruments developed by NASA. BRDF is an important parameter which gives information about all other optical properties of a surface and can be used to know optical performance of that surface. The current work describes the experiments and an automated device developed, called reflectometer, to measure the BRDF of Z302 at different angles and wavelengths of light. The results are reported for different thickness samples of Z302 coating, and two different wavelengths of light that belong to the visible and ultraviolet spectrum of light.