Measurement of optical scattered power from laser-induced shallow pits on silica

A model describing far-field scattered power and irradiance by a silica glass slab with a shallow-pitted exit surface is experimentally validated. The comparison to the model is performed using a precisely micromachined ensemble of ∼11  μm wide laser ablated shallow pits producing 1% of the incident beam scatter in a 10 mrad angle. A series of samples with damage initiations and laser-induced shallow pits resulting from 351 nm, 5 ns pulsed laser cleaning of metal microparticles at different fluences between 2  J/cm2 and 11  J/cm2 are characterized as well and found in good agreement with model predictions.