两种反射膜系的激光热力损伤特性

Thermal and mechanical damage characteristics of two reflective multilayer films under laser irradiation

在驻波场理论基础上,用表面和界面强吸收理论模型,计算出了激光辐照下两种不同反射膜系中温度场的“多峰”分布特性,分析了激光对薄膜的热力损伤特性、主要破坏模式和阈值条件。结果表明,光学薄膜对激光能量的吸收,主要由驻波场分布及膜层的消光系数决定;膜系表面的杂质吸附层和界面吸收层是膜系的主要能量沉积区,从而在这些界面形成温度场的“多峰”分布,界面因此成为最容易受激光损伤的部分。导致光学薄膜激光损伤的主要模式为膜层熔融和脱落两种。如果膜层中含有杂质,则容易诱导杂质处膜层剥落破坏。

Based on the standing-wave theory, a theoretical model with high energy absorption at the surface and interfaces is employed to describe laser-induced damages to optical multilayer films. The temperature distributions in two types of reflective multilayer films are calculated, and the characteristics, modes and damage thresholds are analyzed. The results show that energy absorption is mainly determined by the distribution of the standing-wave and extinction coefficients of the material. Multi-peaks over the temperature profiles are found at the surface and interfaces, where the optical multilayer films are prone to damage. Melting and falling off are two main kinds of damage mode, while inclusion, if present, may cause spallation of the layers.