在惯性约束聚变(ICF)终端光学组件(FOA)的精密装校过程中，超大超薄KDP晶体面形在重力作用下会发生畸变，从而导致晶体内部晶轴发生改变，进而由于波前相位失配而极大地降低高功率激光的频率转换效率。针对大口径薄型Ⅰ/Ⅱ类KDP晶体在非垂直放置状态下出现的附加面形问题，利用有限元分析软件，建立了具有不同初始面形的KDP晶体及其“杠杆式”夹持系统的模型，对晶体经夹持系统夹持后的附加面形分布进行了仿真计算，并讨论了支撑条上表面的加工误差类型及大小、晶体初始面形对KDP晶体附加面形的影响。研究结果表明: “杠杆式”夹持系统能有效改善大口径薄型KDP晶体因重力作用而引起的附加面形变化;晶体边缘部分的加工误差对KDP晶体附加面形有较大影响。

In final optical assembly(FOA) of high peak power solid-state laser system, the surface shape and the internal axis of ultra-thin KDP crystals with large-aperture can be changed due to the gravity, resulting in the mismatched wavefront phase and the decrease of the harmonic conversion efficiency and beam quality of high-power lasers. In order to improve and optimize the additional surface shapes of type Ⅰ/Ⅱ KDP crystals with large-aperture, the models for different original surface shapes of KDP crystals and “lever-type” fixture systems are built up by ANSYS software and the additional surface shapes of KDP crystals clamped by the fixture systems are simulated. Furthermore, the influence of the processing errors of the upper surface of the supporting bars and the original surface shapes of the KDP crystals on the additional surface shapes of KDP crystals are also discussed. The results show that the “lever-type” fixture system can efficiently improve the additional surface shapes of ultra-thin KDP crystals with large-aperture under gravity. The surface shapes of KDP crystals with fixture system are notably influenced by the processing error on the edge of crystal surface.