Systematic Variation of Microstructure in Vapor-Deposited Ag Coatings on Cu Substrates: Studies of the Effect of Microstructure on Laser Damage Thresholds

Abstract

The attainment of high power density lasers is, in many respects, limited by the properties of windows and mirrors; and is therefore materials limited. Aside from microcracks, voids, and other structural features contributing to laser-induced degradation, there has been some indication that other microstructural phenomena such as the presence of crystal defects might also contribute. While the subject of short-pulse laser damage at the surfaces of both coated and uncoated dielectric materials has received considerable attention in recent years, little attention has been paid to the systematic evaluation of mirror surface and surface coating microstructure on laserinduced damage (or damage threshold). Although some preliminary work has been done on determining the relationship between the optical properties of metal films and departures from crystalline perfection of the films, no efforts have been made to determine the effects of metal coating microstructure on laser damage thresholds.