抑制反射镜热变形影响的支撑方式优化设计

Optimization Design of the Constraint Method to Repress the Thermal Deformation of Reflecting Mirror

在高功率激光应用系统中,常通过反射镜对光束进行扩聚束、重定向、波前校正等控制。但控制系统中的各类反射镜会吸收部分光能从而形成非均匀温度场,使反射镜产生形变,进而影响反射光束质量。由于支撑方式与温度场共同决定反射镜的变形结果,因此在光束控制系统设计中,需要研究最佳的反射镜支撑约束方式。基于热弹性力学,提出了不同镜面支撑方式减小镜面热变形的方法;对几种常见支撑约束方式下的反射镜的温度场、变形量进行了量化仿真分析;对比了镜面的总变形量、光斑区域相对变形量、光斑区域相对变形量引入的波前像差。结果显示:对反射镜背面采用小块区域约束的支撑方式镜面相对变形量最小;对反射镜背面采用刚性约束的支撑方式镜面相对变形量最大;后者可以有效减小镜面相对变形量约98.4%。实验和仿真分析的镜面光斑区域的相对变形量十分接近,波前图像基本一致。这些研究结果为光束控制系统镜体支撑的选型和设计提供了理论支持。

In highpower laser applications,it is common to use reflecting mirrors for controlling the beam,such as beam expansion,redirection and wavefront correction.However,various types of reflecting mirrors in the control system will absorb some of the light energy,forming a nonuniform temperature field,which cause deformation of the reflecting mirrors and ultimately affect the quality of the reflected beams.Since the support method and temperature field jointly determine the deformation of the reflecting mirrors,it is necessary to study the optimal support method for reflecting mirrors in the design of beam control systems.Based on thermoelastic mechanics,the methods to reduce the thermal deformation of reflecting mirrors using different mirror support methods are proposed,the temperature field and deformation of the reflecting mirrors under several common support constraints are quantified and simulated.The total deformation of the mirror,the relative deformation of the spot area,and the wavefront aberration introduced by the relative deformation of the spot area are compared.The results show that the support method with a small area constraint on the back of the reflecting mirror has the smallest relative deformation,and the support method with a rigid constraint on the back of the reflecting mirror has the largest relative deformation.The relative deformation of the mirror with a rigid constraint can be effectively reduced by about 98.4%.The experimental and simulation results are very close in terms of the relative deformation of the mirror in the beam spot area,and the wavefront images are essentially identical.These results provide theoretical support for the selection and design of mirror support in beam control systems.