Abstract

The National Aeronautics and Space Administration's In Situ Contamination-Effects Facility at Marshall Space Flight Center has been used to measure scattering from molecularly contaminated optical surfaces in the VUV. Light scattering has been measured on good optical surfaces in real time during molecular-contaminant deposition. The measurements used noncoherent VUV sources with a predominant wavelength of 1236 Å. The scattered light was detected by a set of three solar-blind VUV photomultipliers. These photomultipliers were arranged at fixed angles, coplaner with the source and target mirror, to measure the forward scatter, specular reflection, and backscatter from the material surfaces. These measurements have been complemented by BRDF measurements made with the Center for Applied Optics' BRDF facility. Optical samples were measured at 6328 Å before and after contamination to correlate with the in situ VUV measurements. This permits verification of possible scaling rules for BRDF measurements between the two regions. The experiment is described, and results of the ongoing program to characterize optical materials exposed to the environment of space are reported.

© 1990 Optical Society of America