Influence of polishing and cleaning on the laser-induced damage threshold of substrates and coatings at 1064nm

Laser-induced damage threshold (LIDT) results on silica substrates and coatings are presented for near-infrared applications. Different polishing and cleaning processes are evaluated. In particular, we investigate the influence of polishing and cleaning on the LIDT of silica substrates and optical coatings deposited by dual-ion-beam sputtering. Laser damage tests were performed at 1064 nm with a 5-ns-pulse Nd:YAG laser, and experiments were made on surfaces of optical components using a 12-µm-diameter focused beam. Accurate damage probability curves are plotted thanks to a reliable statistical measurement of laser damage. Use of a statistical model permits us to deduce the densities of laser damage precursors. We find a significant improvement of the LIDT of our coatings on choosing the appropriate cleaning and polishing process.