Acid treatment for raising the surface damage threshold of laser glass

Results of damage experiments on superpolished glass surfaces are briefly presented. It is found that polishing of glass beyond what is readily obtained by conventional polishing is not effective in increasing the damage threshold. Removal of contaminants is apparently more important, and this can be accomplished by treatment with hot nitric acid or water. The threshold can be increased by as much as a factor of 3 by using hot nitric acid. The effectiveness of the acid treatment is time dependent and the increase in effectiveness fits a diffusion model.