Laser Induced Damage of Optical Elements-a Status Report.

In the application of high-power lasers, damage to active laser materials, and to components of laser system, generally determines the limit of useful laser performance. Accordingly, there is great interest in reducing the susceptibility of optical elements ot damage. Damage in transparent dielectrics arises from three major causes, particulate inclusions or microinhomogeneities in the material, self-focusing within the materials, and surface damage due to plasma formation. The state of understanding of these phenomena, and the thresholds observed, where they have been determined, will be discussed. Dependence on pulse length will also be considered. Although most of the research accomplished to date on laser damage has concentrated on Nd-glass, the advent of very high-powered gas lasers has stimulated interest in the development of damage resistant component materials for use in the ir. Crystalline dielectrics appear to be the most likely candidate materials for ir windows. Nonlinear optics materials are particularly susceptible to damage, since they are generally exposed to high intensity radiation. Asa final item, damage in thin film dielectric coatings are considered.