Thermoelastic and ablation mechanisms of laser damage to the surfaces of transparent solids

An investigation is reported of the relationships governing laser damage to the surfaces of transparent dielectrics, initiated by absorbing inclusions, under repeated irradiation conditions. It is shown that ultrashort pulses produce damage by the ablation mechanism, whereas ‘long’ laser pulses cause damage by the thermoelastic mechanism. The relationships established for the change in the damage mechanism with change in the pulse duration apply also to intrinsic (collisional and multiphoton ionisation) damage mechanisms.