PRECISE VISUAL INSPECTION

摘要

Contaminants degrade the optical or thermal properties of spacecraft systems. Judging the extent of corruption is not easy on sensitive surfaces, where they are often too delicate or large to be moved to the laboratory for analysis. Witness mirrors, tape lifts on adjacent surfaces, and subjective visual assessment are some of the tools now used to evaluate the extent of contamination. This paper derives a method of precise visual inspection that assumes a minimum visible particle size that can be easily evaluated for any observer. It also assumes a log-normal particle size distribution, but not the slope of it. By counting the particles visible in a convenient unit area, the fractional area coverage can be calculated.