NOVEL ABLATION OF FUSED QUARTZ BY PREIRRADIATION OF VACUUM-ULTRAVIOLET LASER-BEAMS FOLLOWED BY 4TH HARMONICS IRRADIATION OF ND-YAG LASER

Preirradiation using vacuum-ultraviolet (VUV) beams of anti-Stokes sti mulated 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-Stok es 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 SiO(x)(x < 2) is created in the fused quartz by photolysis using the anti-Stokes bea ms. Each effect of the preirradiation and the succeeding fundamental b eam irradiation in the ablation process is discussed.