Effect of substrate temperature and ion assistance on nanosecond laser-induced damage threshold in high reflection dielectric coatings

Abstract

An influence of substrate temperature and working gas in coating plant during evaporation process on the laser-induced damage threshold (LIDT) of high reflection dielectric coatings was experimentally investigated. Also a LIDT comparison of ion assisted deposition (IAD) and conventional electron-beam evaporation (non-IAD) coatings fabricated under the same substrate temperature (300 °C) was performed. A set of different type high reflection mirrors were tested for LIDT at 532 nm for 3.4 ns pulses: one type of non-IAD and six types of IAD evaporated at different substrate temperatures and different working gases. All coatings were made on BK7 glass substrates from ZrO 2 and SiO 2 . The computer controlled test station for LIDT measurements according to the requirements of current ISO 11254-2 standard was used. All measurements were performed at 10 Hz pulse repetition rate (S-on-1 test). The tests were performed at fixed spot size. Strong LIDT dependence on substrate temperature of was observed.