In situ investigation of a correlation between fluorescent defects and UV pulse laser-induced damage on fused silica optics surfaces

An in situ methodology was developed to ascertain the relationship between steady-state fluorescent defects and laser-induced damage on the surface of fused silica optics. This study examined the effects of various types of fluorescent defects, their brightness, and surface treatments on laser-induced damage. The results indicate that the probability of damage is contingent upon the type, brightness of fluorescent defects, and the laser radiation flux. Specifically, at a radiation flux exceeding 20 J/cm², all fluorescent defects were found to induce damage. However, at a radiation flux of 12 J/cm², the damage probability of fluorescent defects in precision polished optics was just approximately 25%. Following dynamic chemical etching (DCE) treatment, the damage probability was further reduced to 6%, and the proportion of fluorescent defects among all damage points decreased from 6% prior to DCE treatment to 2%. These results suggest that the majority of damage precursors on the precision polished surface of fused silica optics lack photoluminescent characteristics. Furthermore, the surface defect modification resulting from DCE treatment appears to enhance the non-photoluminescent characteristics of the damage precursors.