根据非稳腔薄片激光器腔内离焦的特点和主动校正的应用需求,针对性地设计离焦变形镜,对激光器腔内离焦进行实时补偿。采用压电陶瓷作为驱动器,圆形镜面圆心处设置1个驱动器,圆周上均布4个驱动器的5通道布局模式,仿真分析了筋板厚度和镜片厚度对离焦的校正效果影响,在优化设计的基础上研制出水冷式离焦变形镜,其静态面形PV值为0.34 μm,波前动态范围为±16 μm。在离焦变形镜和二维变形镜组合模式下进行了薄片激光器强光主动光学校正试验,谐振腔腔内像差PV值从6.76减小到1.44,光束质量从19.5提高到6.5,有效地改善了输出光束质量,验证了离焦变形镜对非稳腔薄片激光器离焦校正的有效性和实用性。

In order to correct the defocus aberration in the thin-disk laser resonant cavity, a special water-cooled deformable mirror named as defocus-correction deformable mirror was designed and manufactured. The defocus-correction deformable mirror has 5 piezoelectric ceramic actuators, one located in the center of the round mirror surface and the other four arranged symmetrically on the mirror’s circular periphery. The simulation of relationship between mirror thickness and surface deformation was carried out to gain the best defocus-correction result. Testing results show that, the deformable mirror, with optical surface quality better than 034 μm PV, has extremely large stroke up to ±16 μm. In the wavefront correction experiments of thin-disk laser systems, the optical quality (β factor) of laser was improved from 19.5 to 6.5, which gives the vivid proof of the capability and effect of the defocus-correction deformable mirror.