Research of thin film damage testing based on photothermal deflection

Abstract

Optical thin film is the weak link in the entire laser systems; its resistant ability of laser induced damage is the bottleneck of laser systems which improve towards high-energy and high-power direction meanwhile. Owing to these, measurement of LIDT has been paid more and more attention to. The laser damage model of film was established. Based on this principle, criterion of photothermal deflection damage was determined. Experimental device based on laser damage model was set up. After experiments of SiO 2 films were conducted, beam offset under different energy was obtained. Comparative analysis of results between image processing method and photothermal deflection method were shown in the article. Experimental results show that photothermal deflection method is more sensitive than image method on measurement of film laser damage.