Influence of surface cracks on laser-induced thermal damage characteristics of optical material

摘要

A thermal damage analysis model of fused silica material with surface crack is established. The distributions of modulated light and temperature field on the optical surface are calculated based on FDTD method. According to the surface temperature distribution, the thermal damage thresholds of materials with different crack scales are analyzed. Furthermore, the variations of the damage thresholds caused by surface cracks with two typical morphologies are compared. Results show that the lengths of the cracks have little effect on the damage threshold. On the contrary, it decreases obviously with the increasing of crack width and depth. In addition, the cracks with sharp rectangular shape are more likely to cause material damage due to the stronger modulation of light field.