Thermal and mechanical damage in K9 glass irradiated by KrF excimer laser

A numerical simulation is performed to calculate temperature and stress distributions in K9 glass sample irradiated by KrF excimer laser using finite element method, and the relationship between laser parameters and damage effect is also studied. The simulation results indicate that the damage of K9 glass irradiated by KrF excimer laser is thermal stress damage when the incident laser energy is low. The stress damage in laser spot area is dominated by compressive stress, and the damage near the edge of the spot or inside the K9 glass is dominated by tensile stress. The thermal stress as shock wave oscillates obviously inside the K9 glass sample. It is shown that repetition frequency and the number of pulses affect damage considerably, and the accumulation of multi-shot laser induced damage in K9 glass is obvious.