Improving Anti-Reflection MgF2 Thin Films by Laser Shock Peening and Investigation of its Laser Damage Threshold

Abstract

This study is divided into two parts. In the first part, the influence of laser shock peening (LSP) on the surface properties of MgF2 thin films is studied. The MgF2 monolayer films with thickness of 100 nm were prepared on a BK7 glass substrate by physical vapor deposition (PVD). An ArF excimer laser with 110 mJ energy, 53 J/cm2 power density, 20 ns pulse duration and wavelength of 193 nm in TEM00 mode was used for the LSP experiments at different (20, 50, 90, and 120) number of the pulses. Transmittance of MgF2 thin films, before and after the LSP treatment, was evaluated by a spectrophotometer and the surface morphology of samples was examined by scanning electron microscope. In the second part, the effect of the LSP treatment on the laser induced damage threshold of a sample irradiated by 90 pulses of the ArF excimer laser was examined.