The direction of this paper is to provide a theoretical model and supporting empirical data for evaluation of laser damage to optical thin films subjected to high power Continuous Wave laser irradiation. Basically, there has been a seeming anomaly in the maximum temperature that optical thin films can withstand before they fail to perform their function. On the one hand, a paper was presented to the Laser Boulder Damage Symposium that clearly provided empirical data that a number of oxide coating materials could reach 59°C to 680°C before failure set ia On the other hand, many investigators have found that coatings have failed at temperatures of 200°C to 300°C.
In this paper we set out to demonstrate that both conditions could be correct, rather than just one or the other. The equations for the absorption and subsequent temperature rise in the multilayer stacks are provided. The temperature rise of the substrate is evaluated and the equations for the actual thermal shock resulting from the conditions in the optical thin films, the substrate, and sensitivity of both to the materials that comprise the optical thin films and the substrates combination. Several coating chemistry combinations and three diverse substrate materials are evaluated and plotted based on measurements made and reported some years ago.