The subsurface defects characterization and 355 nm nanosecond
laser induced damage performance have been analyzed step
by step for every pretreatment condition in this paper. We can conclude
that most of metal impurities defects (especially for Ce element)
of fused silica can be dissolved and damage performance
increase correspondingly by strong acid solution. Laser damage
resistance of fused silica optics is further improved through the removal
of subsurface damage which is removed by HF-based etchants.
As a synthetical and macroscopic characterization of all
microscopic defects, thermal absorption has a good correlation
with laser-induced damage performance. The width and depth of
etched open cracks, the surface roughness and the impurities
deposited on optics surface all increase with the etching process
when the HF-based etching depth exceeds one value. These factors
maybe cause the deterioration of laser damage performance for
deep etched sample. Hence, it is necessary to monitor and control