CO2-laser polishing for reductoin of 351-nm surface damage initiation in fused silica

We have applied a carbon dioxide (CO 2 ) raster scanning laser polishing technique on two types of fused silica flat optics to determine the efficacy of CO 2 -laser polishing as a method to increase the 351-nm laser damage resistance of optic surfaces. R-on-1 damage test results show that the fluence for any given 355-nm damage probability is 10-15 J/cm 2 higher (at 3 ns pulse length, scaled) for the CO 2 -laser polished samples. Poor quality and good quality surfaces respond to the treatment such that their surface damage resistance is brought to approximately the same level. Surface stress and the resultant effect on wavefront quality remain key technology issues that would need to be addressed for a robust deployment.