In Situ Measurements of Scattering from Contaminated Optics in the Vacuum Ultraviolet

NASA's In Situ Contamination Effects Facility, Marshall Space Flight Center has been used to measure the time dependence of the angular reflectance from molecularly contaminated optical surfaces in the Vacuum Ultraviolet(VUV). The light scattering measurements are accomplished in situ on optical surfaces in real time during deposition of molecular contaminants. The measurements are taken using non-coherent vacuum ultraviolet (VUV) sources with the predominant wavelengths being the Krypton resonance lines at 1236 and 1600 Angstroms. Detection of the scattered light is accomplished using a set of three solar blind VUV photomultipliers. An in-plane VUV BRDF experiment is described and details of the on-going program to characterize optical materials exposed to the space environment is reported.