Vacuum laser damage test bench

Abstract

This work summarizes the results from an extensive test campaign in which space-based laser optics were qualified for the upcoming ESA ADM-Aeolus mission. 14 different types of optical components from different suppliers were tested at the Nd:YAG laser wavelength according to the ISO standard 11 254 - 2 for multiple pulse testing. A new technique based on transient pressure sensing was developed to monitor the occurrence of damage on a sample surface exposed to a vacuum environment. Parallel testing of reference samples showed a distinct degradation under vacuum compared to atmospheric or pressurized environment. For all samples tested we found a typical behavior in the characteristic damage curves attained: A sharp drop in LIDT for small pulse numbers followed by a smooth decrease for larger pulse numbers (laser fatigue effect).