Experimental study of 355 nm laser damage ignited by Fe and Ce impurities on fused silica surface

Abstract

Laser-induced damage on fused silica surface is often ignited by absorbing impurities introduced by polishing processing. In order to analyze laser damage mechanism induced by Fe and Ce impurity on fused silica surface, this paper presents laser induced damage threshold of three types of fused silica surface dealed with traditional chemo-mechanical or magnetorheological finishing and carries out the surface impurity analysis, photo-thermal absorption analysis and gray haze damage mechanism analysis. The results show the significant different Ce and Fe impurities on the surface of the three kinds of samples. The two impurities both have a serious influence on laser-induced native damage. The analyses of photo-thermal absorption on the surface of optical element show that the haze damage pits morphology is related to the absorptivity of nanoparticles. The native surface damage threshold induced by Fe nanoparticle is lower than by Ce nanoparticle by analyzing atomic force microscopy images and scanning electron microscopy images. The conclusion is different from previous reports which believe Fe element shows a weak relation with laser-induced damage. This paper also analyzes the relationship between gray haze damage and native damage for the first time. The results are helpful to understanding laser induced damage of fused silica ignited by impurities.