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Damage morphologies of Al2O3 and Fe particles attached on the input surface of fused silica after irradiation by a 355  nm laser.

Particulate contamination on the optical surface can seriously degrade the performance of optics working in the high peak power laser system. In this study, we show that the nature of optical damages on the input surface induced by particles depends on the optical property of the particles. Ceramic Al2O3 particles tend to cause micro-fractures to the optical surface, but metallic Fe particles mainly undergo ablation on the substrate. Different microscopes are used to characterize their damage morphologies, and the light distribution and thermal evolution of two different particles are simulated, focusing on better understanding their special damage morphologies.