中国激光, 2017, 44 (3): 0302006, 网络出版: 2017-03-08
光学元件激光诱导损伤分析及实验研究
Analysis and Experimental Investigation of Laser Induced Damage of Optics
激光制造 激光损伤阈值 表层杂质 亚表面缺陷 化学刻蚀 laser manufacturing laser damage threshold surface impurity subsurface defect chemical etching
摘要
通过激光损伤实验,系统分析了传统研磨抛光加工工艺中表面杂质、刻蚀时间、亚表层缺陷和划痕宽深比对熔石英元件激光损伤阈值的影响。结果表明:擦洗后熔石英元件的激光损伤阈值为21.6 J/cm2,未经擦洗的元件的激光损伤阈值为11.28 J/cm2,受表层杂质影响激光损伤阈值大幅度降低,而有缺陷位置处的激光损伤阈值明显比无缺陷位置处的低。刻蚀时间的增加会使工件表面粗糙度和缺陷尺寸逐渐增大,导致光学元件激光损伤阈值大幅度下降,因此需要合理选择化学刻蚀时间。亚表层缺陷会对入射光场产生调制作用,造成局部区域反射光、散射光及入射光相互叠加,最终导致材料破坏而产生激光损伤。随着刻蚀时间的增加,划痕的宽深比会逐渐增大,可以逐渐减弱划痕对光场的调制作用,从而降低激光损伤发生的概率。
Abstract
The influences of surface impurities, etching time, subsurface defects and the width to depth ratio on the laser damage threshold of fused silica optics in the traditional grinding and polishing process are systematically analyzed by laser damage experiments. Results show that the laser damage thresholds are 21.6 J/cm2 and 11.28 J/cm2 for wiped and non-wiped optics, respectively. The laser damage threshold is greatly reduced by the surface impurities, while the laser damage threshold at the defect area is significantly lower than that at no defect area. The increase of the etching time increases the surface roughness and defect size of the workpiece, which leads to a significant decrease in the laser damage threshold of the optics, so a reasonable choice of chemical etching time is required. The incident light field can be modulated by subsurface defects, resulting in local area reflected light, scattered light and incident light superimposed on each other, eventually leading to laser damage of optical material. The width to depth ratio of the scratch increases with the etching time, which can gradually weaken the scratch on the light field modulation, thereby the probability of occurrence of laser damage for fused silica optics is reduced.
王洪祥, 沈璐, 李成福, 白桦, 周岩. 光学元件激光诱导损伤分析及实验研究[J]. 中国激光, 2017, 44(3): 0302006. Wang Hongxiang, Shen Lu, Li Chengfu, Bai Hua, Zhou Yan. Analysis and Experimental Investigation of Laser Induced Damage of Optics[J]. Chinese Journal of Lasers, 2017, 44(3): 0302006.