Abstract

Stains on polished surfaces are troublesome because they occur after the polishing process is complete. Sometimes the stains become apparent only after thin film deposition, when the additional coated material makes them visible. The major cause of staining and dimming is dihydrogen oxide (i.e., water), the same liquid that is almost indispensable for glass polishing. Because water and aqueous solutions are present during most phases of optical fabrication, polished surfaces should be coated with proper protective film at all times. In addition to being water resistant, the protective film should be rigid enough and not too acidic. Flexible films will cause blocked elements to shift during polishing while acidic films, such as some pitch or rosin mixtures, will contribute to staining.

© 1984 Optical Society of America