The laser damage resistances of four crystals (CaF2,MgF2,Al2O3,and SiO2) and fused silica (JGS1) irradiated at 355 nm (8 ns,300-on-1) are reported.The laser-induced damage threshold is measured using a tripled Nd∶ YAG laser system.The results obtained from the pure crystals are in accordance with their specific optical,mechanical,and thermal properties.An empirical law based on the Franz Keldysh effect can interpret the experimental results.