高功率激光作用下光学元件非线性热效应研究

为了研究高功率激光作用下光学元件热效应的非线性特性对光束质量的影响, 基于热传导、热弹性力学、物理光学等基础理论, 采用有限元分析方法, 进行了高功率连续激光(功率密度约为500kW/cm2)作用下光学元件的温度场和位移场的计算; 分析对比了各个参数的非线性特性对光学元件热效应的影响; 探讨了不同材料、不同形状光斑辐照下的光学元件非线性热效应。结果表明, 高功率连续激光作用下光学元件所反映出的热学、力学和光学吸收存在着不同程度的非线性效应, 其强弱取决于光学元件材料、光斑形状等因素; 高斯激光辐照熔石英样品且吸收率为100×10-6时, 考虑物性参数和温度边界条件的非线性, 会引起表面最大温升16%的相对误差和表面变形峰谷值10%的相对误差。这一结果为开展与此相关的研究提供了一些新思路。

Nonlinear thermal effects of optical components irradiated by high-power laser beam

In order to investigate the influence of the nonlinear characteristics of thermal effects of optical components on the beam quality irradiated by high-power laser beam, based on the basic theories of heat conduction, thermoelasticity, and physical optics, etc., with the help of finite element analysis, the temperature field and displacement field of optical components irradiated by high-power continuous-wave laser (the power density is approximately 500kW/cm2) were presented. The influences of various parameters on the thermal effects of optical components were analyzed and compared. Moreover, the nonlinear thermal effects under different conditions were discussed. The results show that the thermal, mechanical, and optical absorption of optical components irradiated by high-power continuous-wave laser present nonlinear effects, and the strengths of these nonlinear effects depend on the materials of the optical components, and the spot shape of the laser beam. When fused silica sample is irradiated by Gaussian laser and the absorption rate is 100×10-6, the nonlinearity without the physical parameters and temperature boundary condition will cause 16% and 10% relative errors for the maximum surface temperature rise and the peak-to-valley surface deformation, respectively. The results presented in this paper is expected to provide some new clues for the related research.