铜膜和铁膜污染物诱导熔石英表面损伤行为的对比研究

采用人工溅射的方式分别在熔石英基片上镀制了光学厚度相近的铜膜和铁膜污染物。研究了熔石英基底在355nm波长的激光损伤阈值。分别采用透射式光热透镜技术、椭偏仪、原子力显微镜和光学显微镜研究了两类薄膜的热吸收、膜层厚度、表面微观形貌以及激光辐照后薄膜的损伤形貌。实验结果表明：熔石英表面的金属膜状污染物均导致基片损伤阈值下降，位于前表面的污染物引起的损伤阈值下降更为严重，约为23％。两种污染物薄膜引起基底的损伤形貌、基底损伤阈值的下降幅度与薄膜的热吸收系数与微观结构有关。从热力学响应角度，结合损伤形貌对污染物诱导熔石英表面形貌的损伤机理进行了讨论。

Experiment of Laser Induced Damage for Different Thin Film Contamination of Cu and Fe on Fused Silica Surface

Fused silica was artificially contaminated to estimate the resistance of fused silica against laser damage. Uniform contamination thin films were prepared by sputtering materials（Cu and Fe）. The laser-induced damage threshold of the two kinds of films was measured. Thermal absorption and surface morphologies of films were investigated by Stanford photothermal solutions, ellipsometer, atomic force microscopy and scanning electron microscopy respectively. Optical microscopy was used to characterize the defects and impurities of films before laser irradiation and damage morphology after laser irradiation, The experimental results showed that the laser damage resistance dropped very uniformly across the entire surface, special on the input surface, about 23 %. The different damage morphologies of films were relative to the different absorption and microstructure. Explanation is presented theoretically with the damage morphologies.