Experiment of laser induced damage threshold for fused silica initiated at thin film contamination of Cu on surface

Fused silica were artificially contaminated to estimate the resistance of fused silica against laser damage. Uniform contamination thin films (less than 10 nm thick) were prepared by sputtering materials(Cu). The loss of transmission of the samples was first measured. They were tested at 355 nm in air with Nd:YAG laser. The damage morphologies were characterized by Nomarski optical microscopy. Both theory and experiments show that the laser damage resistance drops very uniformly across the entire surface，about 20%, the damage morphology contrary with that of the clean silica shows many pits on the surface, and the fused silica melts. A model for light absorption and the heat deposition was established to estimate damage thresholds. The damage threshold predictions are in qualitative agree