Cryogenic BRDF Measurements at 10.6 micrometers and 0.63 micrometers on Contaminated Mirrors
Abstract
Effects of contaminants on optical surface are concern for space-based systems. Many systems contain cryogenic optical systems that operate at temperatures where gases condense. This study presents experimental results of the effects of condensed gases and spacecraft contaminants on highly polished (superpolished) mirror surfaces cooled, under vacuum to temperatures near 16 K and 70 K. After condensing contaminants on the mirror, the change in the bidirectional reflectance distribution function (BRDF) was obtained at wavelengths of 10.6 and 0.6328 um for various contaminant thicknesses up to 15 um. For a mirror surface of 16 K, BRDF changes for the following contaminant films were obtained: air, N2, 02, H2O, CO, CO2, and Ar. For a mirror surface near 70 K, the BRDF changes from condensed films of the following outgassing effluents were measured: RS12M polycyanate, Nusil CV2500 silicone, Solithane 113/Cl 13-300 urethane, RTVS60 silicone, and 1120. In addition, using measured optical properties and the thin-film interference theory-based computer program CALCRT, the spectral reflectance of an 80 K aluminum mirror was calculated for H2 0, CO and RTV560. This report was sponsored by the Ballistic Missile Defense Organization (BMDO) through Johns Hopkins Applied Physics Laboratory (JHU/APL) and by the Jet Propulsion Laboratory (JPL) Space Environmental Effects Program.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1995
- Accession Number
- ADA291611
Entities
People
- B. L. Seiber
- Bobby E. Wood
- R. J. Bryson
- W. T. Bertrand
Organizations
- Arnold Engineering Development Complex