高抗激光损伤阈值光栅后处理抛光技术研究

Research on post-processing polishing technology of pulse compression gratings with high laser damage threshold

脉冲压缩光栅是实现高能量激光的核心光学元器件,其制造过程中产生的表面污染物和微结构缺陷成为限制高功率激光系统发展的技术瓶颈,为了提升光栅的激光诱导损伤阈值,提出利用磁性复合流体进行脉冲压缩光栅(PCG)后处理抛光研究。对抛光前后光栅样品的微观结构,表面形貌、表面粗糙度、衍射效率和激光诱导损伤阈值等参数进行测量,进行抛光前后光栅表面质量和光栅性能的评估。研究发现,磁性复合流体抛光能够在不破坏实际光栅结构的前提下抑制加工过程产生的毛刺,微结构缺陷等;经3 min抛光后,光栅顶部表面粗糙度从21.36 nm下降到3.73 nm;激光诱导损伤阈值从2.8 J/cm^(2)提高到3.8 J/cm^(2),抗激光损伤性能提升35.7%,且不影响衍射效率。实验结果表明:磁性复合流体抛光是一种可以提高光栅元件表面质量,提升光栅元件光学性能的有效方法。

Pulsed compression gratings are critical optical components for the development of high-energy lasers.However,laser manufacturing processes often generate surface contaminants and microstructure defects,leading to technical challenges limiting the advancement of high-power laser systems.To improve the laser-induced damage thresholds of gratings,a novel method involving magnetic compound fluid polish⁃ing for pulse compression gratings was developed herein.The microscopic structure,surface morphology,surface roughness,diffraction efficiency,and laser-induced damage thresholds of grating samples were evaluated before and after polishing.This assessment allowed a comparison of the grating surface quality and performance before and after polishing.Consequently,the magnetic compound fluid polishing process was found to effectively minimize burrs and microstructure defects generated during the manufacturing pro⁃cess without damaging the intrinsic grating structure.After 3 min of polishing,the grating surface rough⁃ness decreased from 21.36 nm to 3.73 nm.Furthermore,the laser damage threshold increased from 2.8 J/cm^(2)to 3.8 J/cm^(2),improving the laser damage resistance by 35.7%without influencing the diffraction efficiency.These results demonstrate that magnetic compound fluid polishing is a highly effective method for enhancing the surface quality and overall performance of grating components.