Fig. 1. Schematic of optical material irradiated by nanosecond pulse laser

Fig. 2. Simulation results for fused silica with smooth surface irradiated by single pulse with energy density of 11.1 J/cm². (a) Diagram of fused silica with smooth surface; (b) temperature distribution; (c) stress distribution

Fig. 3. Simulation results for fused silica with scratch surface irradiated by single pulse with energy density of 5.4 J/cm². (a) Diagram of surface scratch; (b) distribution of relative light intensity factor caused by surface scratch; (c) temperature distribution; (d) stress distribution

Fig. 4. Experimental optical path of laser damage test and stress on-line measurement system

Fig. 5. Experimental and simulation results for fused silica with smooth surface irradiated by laser. (a1) Experimental result and (b1) simulation result of damage morphology at laser energy density of 662.1 J/cm²; (a2) experimental result and (b2) simulation result before rotation of orthogonal polarizers; (a3) experimental result and (b3) simulation result after rotating orthogonal polarizers simultaneously by 45°; (a4) experimental result and (b4) simulation result of stress distribution

Fig. 6. Damage morphologies and stress distributions of fused silica with smooth surface irradiated by single pulses with different laser energy densities

Fig. 7. Maximum stress of laser irradiated fused silica with smooth surface versus laser energy density

Fig. 8. Scratch morphology on surface of fused silica made with diamond glass knife

Fig. 9. Damage morphologies and stress distributions of fused silica with scratch surface irradiated by single pulses with different laser energy densities

Fig. 10. Maximum stress of laser irradiated fused silica with scratch surface versus laser energy density

Fig. 11. Effects of scratch size on stress of fused silica after laser irradiation. (a) Maximum stress versus scratch width; (b) maximum stress versus scratch depth