变形镜受热变形引起的波前畸变仿真及补偿

Simulation and compensation of wavefront aberration caused by deformable mirror thermal deformation

针对变形镜自身受强激光辐照后热变形问题,利用ANSYS的多物理模型建立了变形镜的热机械模型并进行了计算。针对受强激光辐照后变形镜吸收了部分热量并产生了0.9μm的变形量,根据该变形镜热畸变分布特征,提出了一种利用补偿镜对热畸变进行补偿的方法,即在一个薄型镜面背后用一些约束头固定构成补偿镜,放置在变形镜的后续光路中。约束头在补偿镜上的位置与极头在变形镜上的位置对应错开分布。对三种不同形状约束头的补偿镜进行了计算,补偿后综合变形量降低到0.35,0.32和0.40μm。利用光束传输因子(BPF)对理想光束通过补偿镜后的效果进行评价,结果表明通过三种补偿镜后BPF值从0.906提高到了0.966,0.971和0.957。进一步的计算表明,补偿效果受约束头尺寸的影响较小。

The thermo-mechanical model of the deformable mirror based on ANSYS multiphysics is provided and calculated.High-energy laser radiation results in a mirror deformation of about 0.9μm.Therefore,according to the characteristic distribution of the thermally-induced deformation,a compensation method is proposed.The compensation mirror,placed in the optical path after the deformable mirror,is composed of a thin mirror and some restriction parts.By contrast with the poles of the deformable mirror,the restriction parts of the compensation mirror are installed in a staggered order.Three types of compensation mirrors with different shapes of restriction parts are calculated.The results show that the values of the thermal deformation reduce to 0.35μm,0.32μm and 0.40μm.Using the BPF（beam propagation factor）to evaluate the compensation effect,the results indicate that the BPF value increases from 0.906 to 0.966,0.971 and 0.957.Further calculations show that the size of the restriction parts has little effect on the compensation effect.