ABSTRACT
Contamination on optical surfaces is bad because it produces scattering and degrades the performance of an optical system. This chapter discusses the effects of contamination on optical measurements, prevention of contamination, techniques for detecting contamination, and methods for removal of contamination. Contamination on optical surfaces can be in the form of particulates or thin continuous or partially continuous films. To prevent contamination from forming on optics during shipping, they should be cleaned just prior to shipping and then shipped in plastic containers that have a minimum of outgassing. Particulate contamination is easy to detect on optical surfaces. If a surface is viewed in a darkened room using a microscope illuminator to direct a beam of light onto the surface, particles light up like little stars. Cleaning of optics comes in many forms depending on the sizes, types, and number of pieces, whether or not they are coated, the type of coating (cleanable or not), and the quality of the optic.
