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Effects Of Contaminants On Bidirectional Reflectance Distribution Function

One of the problems in spacecraft contamination assessment has been the scarcity of data on the effects of contaminants on optical surfaces. This study measured the effects of collected volatile condensable material (CVCM) on bidirectional reflectance distribution function (BRDF) in situ and the effects of particles on BRDF monitored ex situ. Low scatter mirrors were scanned from 1 to 600 off the specular beam at wavelengths of 10.6 μm and 0.633 μm. The in situ BRDF tests were performed with CVCM from Chemglaze Z-306 over 9922 primer (thickness from 60 to 110 nm), M-773 adhesive (thicknesses from 20 to 95 nm), and multilayer insulation (thickness 57 nm). The effects of vacuum ultraviolet radiation on the CVCM's BRDF was also determined. Ex situ BRDF tests were performed using four different size polystyrene spherical particles (5.2 to 22.2 μm mean diameters) and four different particle density distributions (from 0.56% to 98%)