激光辐照下铝膜反射镜温升和热应力的计算

分析了激光对以K9玻璃为基体的铝膜反射镜的加热问题，将铝膜作为平面热传导，K9玻璃基体作为三维热传导，用有限元法计算了温度分布和K9玻璃基体的热应力分布，讨论了反射率和激光传输距离对温升和热应力的影响。结果表明，二者对温升和应力的影响很大，铝膜反射率增大，温升和应力变低，激光传输距离增加，温升和应力也变低。铝膜的破坏阈值大于K9玻璃的破坏阈值，在确保铝膜反射率的同时，根据K9玻璃基体应力小于其抗拉强度来选择合适的传输距离，可避免反射镜破损。

Calculation of laser-induced temperature increment and thermal stress of Al-film reflector

The planar thermal conduction of Al-film and three-dimentional thermal conduction in K9 glass (substrate) when an Al-film reflector was irradiated by laser beam were analysed. The distribution of temperature and thermal stress in the K9 glass was calculated using finite element method. The influence of reflectivity and transmission distance of laser on the temperature increment and thermal stress of the reflector was also discussed. The transmission distance should be chosen appropriately to keep the reflector out of crack.