Phase modulation in high power optical systems caused by pulsed laser-driven particle ablation events

Surface modification of fused silica windows caused by the laser ablation of surface-bound microparticles is investigated. Using optical and electron microscopies between laser pulses, we detail the ablation, fragmentation and dispersal of 2-150 m diameter particles of various materials. Following complete ablation and ejection of all debris material, surface pitting was found to be highly dependent on material type and particle size. Subsequent light propagation modeling based on pit morphology indicates up to ~4x intensification. Understanding this class of non-local, debris-generated damage is argued to be important for effective design of high-power optical windows and debris-mitigation strategies.