Effect of organic pollution on surface quality and laser damage in fused silica

Abstract

Increases in the laser damage threshold of fused silica have been driven by the successive elimination of near-surface damage precursors such as polishing residue, fractures, and metal ions. In this work, we show that trace impurities used to process fused silica optics may be responsible for the formation of carbonaceous deposits. Firstly we use surrogate materials such as sugar, potassium hydrogen phthalate, medical Vaseline to show that organic compounds precipitated onto fused silica surfaces form discrete damage precursors. Secondly, we test the impact of these organic compounds on the damage threshold and conduct cleaning and removal experiments on these organic compounds. By cleaning, etching, and other treatment processes, the suppression of most organic pollutants is achieved. Finally, the control effect of organic pollutants is verified through damage testing.