Residual stress near cracks of K9 and fused silica under 1064 nm nanosecond laser irradiation

Abstract

Measurements of birefringence induced in K 9 and fused silica specimens by cracks produced by 1064 nm Nd : YAG laser have been presented. The Birefringence data is converted into the units of stress, thus permitting the estimation of residual stress near crack. The intensity of residual stress in K 9 glass is larger than that in fused silica under the same condition. The similarity of residual stress distribution along the y -axis reveals that the nature of shock wave transmission in optical materials under 1064 nm laser irradiation is the same with each other. The value of residual stress can be influenced by laser parameters and characterization of optical material. Simulation based on a theoretical model giving the residual stress field around a crack is developed for comparison with experiment results. The probability of initial damage and the direction of the energy dissipation in cracks determine the residual stress distribution. The thermal stress coupling enlarges the asymmetry of residual stress distribution. Residual stress in optical material has a strong effect on fracture and should be taken into account in any formulation that involves the enhanced damage resistance of optical components used in laser induced damage experiments.