Recovery of fused silica surface damage resistance by ion beam etching

An increase of photoluminescence induced by laser irradiation in vacuum was observed for the fused silica. The degradation of transmittance and damage resistance performance of fused silica surfaces may be due to substoichiometric silica and a sufficient defect population introduced in the near surface. When the laser-irradiated surface layers were removed by ion beam etching, the laser-induced damage threshold recovered to that of un-irradiated samples. The photoluminescence also decreased after ion beam etching. According to the calculated etching depth, the laser-induced defects formed in the surface layer of 10–20 nm when different parameters used during vacuum exposure. In addition, the evolution of surface root-mean-square microroughness as a function of ion beam etching time was studied by the optical interferometric technique and atomic force microscopy.