Novel ablation of fused quartz by preirradiation of vacuum-ultraviolet laser beams followed by fourth harmonics irradiation of Nd:YAG laser

Abstract
Preirradiation using vacuum‐ultraviolet (VUV) beams of anti‐Stokes stimulated Raman scattering VUV laser, followed by the fundamental beam (266 nm) irradiation, provides a novel scheme for fused quartz ablation. The preirradiation of 5th‐ (171 nm) or 6th‐ (160 nm) order anti‐Stokes beams realizes significant ablation with the succeeding fundamental beam irradiation of a laser fluence less than the ablation threshold. X‐ray photoelectron spectroscopy analysis reveals that SiOx(x < 2) is created in the fused quartz by photolysis using the anti‐Stokes beams. Each effect of the preirradiation and the succeeding fundamental beam irradiation in the ablation process is discussed.