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光学薄膜是激光系统中最易损坏的薄弱环节。在高重复频率脉冲激光辐照下,光学薄膜表面温度急剧上升,导致膜层应力、结构发生变化,最后出现宏观的灾难性损伤。从实验上研究了重复频率10kHz脉冲激光辐照下光学薄膜元件的温度变化,分析了影响薄膜温度变化的众多因素。结果表明,在激光光斑确定的情况下,薄膜的温升主要取决于激光功率密度,其次是膜系最外层高折射率层的驻波场峰值,最后是膜系的吸收率及镀膜材料。
Optical films are the most vulnerable weak points in laser systems. Under high repetition rate pulsed laser irradiation, the surface temperature of the optical thin film rises sharply, resulting in the change of the stress and structure of the film and finally the macroscopic catastrophic damage. The temperature variation of the optical thin film element irradiated by 10 kHz pulsed laser with repetition rate was experimentally studied, and many factors influencing the temperature change of the thin film were analyzed. The results show that the temperature rise of the film depends mainly on the laser power density when the laser spot is determined, followed by the peak value of the standing wave field of the outermost high refractive index layer of the film system, and finally the absorption rate of the film system and the coating material.