变形镜结构参数对高功率激光相位特性的影响

Effect of Structural Parameters of Deformable Mirrors on Phase Characteristics of High-Power Laser

在高功率连续激光辐照下,变形镜(DM)表面产生的热形变会对入射激光引入附加相位畸变,进而降低光束质量。利用有限元分析软件ANSYS建立了变形镜模型,分析比较了变形镜与高反镜热形变的特点,并讨论了变形镜结构参数对入射激光相位特性的影响。研究结果表明:与高反镜相比,变形镜的热形变更为明显;变形镜极头间距越小,热形变带来的高频相位畸变越多;极头长度对高频成分的影响较大,极头长度越短,热形变带来的高频成分越多,因而适当增加极头长度能够降低热形变带来的高频相位畸变;增大极头直径能使高频畸变所占比例有所降低,但会减弱变形镜的校正能力,因而在实际设计时应综合考虑。计算结果可为变形镜的参数优化设计提供一定参考价值。

The thermal distortion of the deformable mirror（DM） arised from the high-power continuous laser beam brings about the phase distortion and further degrades the beam quality. The model for the DM is built up using the finite element analysis software ANSYS. The characteristics of the thermal distortion of the DM and the reflective mirror are analyzed and compared. The influence of structural parameters of the DM on the incident light phase are also discussed. The results indicate that, the thermal distortion of the DM is more obvious compared with the high reflective mirror. The high frequency phase distortion introduced by thermal distortion increases with the decreasing of the spacing of heads. The length of heads exhibits a significant influence on the high frequency components and the high frequency phase distortion increases with the decreasing of the length of heads. As a result,high frequency phase distortion introduced by the thermal distortion can be diminished through increasing the length of heads appropriately. The proportion of the high frequency phase distortion decreases with the increasing of the diameter of heads, leading to the decreasing of correction capability. Consequently, the diameter of heads should be considered comprehensively in the practical application. The results obtained can provide valuable reference for the parameter optimization of the DM.