Influence of Vacuum Organic Contaminations on Laser-Induced Damage of 1064nm Anti-Reflective Coatings
Influence of Vacuum Organic Contaminations on Laser-Induced Damage of 1064 nm Anti-Reflective Coatings

We investigate the influence of vacuum organic contaminations on laser-induced damage threshold (LIDT) of optical coatings. Anti-reflective (AR) coatings at 1064\,nm made by Ta2O5/SiO2 are deposited by the ion beamsputtering method. The LIDTs of AR coatings are measured in vacuum andin atmosphere, respectively. It is exhibited that contaminations in vacuum are easily to be absorbed onto optical surface because of lower pressure, and they become origins of damage, resulting in the decrease of LIDT from 24.5J/cm2 in air to 15.7J/cm2 in vacuum. The LIDT of coatings in vacuum has is slightly changed compared with the value in atmosphere after the organic contaminations are wiped off. These results indicate that organic contaminations are the main reason of the LIDT decrease in vacuum. Additionally, damage morphologies have distinct changes from vacuum to atmosphere because of the differences between the residual stress and thermal decomposability of filmy materials.