We present the birefringence measurements induced in K9 specimen by cracks produced by 1 064-nm Nd：YAG laser. The birefringence data are converted into units of stress, permitting the estimation of residual stress near cracks. The laser parameters and characterization of the optical material influence the value of residual stress. Residual stress in optical materials can affect fracture; thus, this factor should be considered in any formulation that involves enhanced damage resistance of optical components used in laser-induced damage experiments. The probability of the initial damage and the direction of the energy dissipation in cracks determine the residual stress distribution. Moreover, thermal-stress coupling enlarges the asymmetry of residual stress distribution. Therefore, the physical mechanism of asymmetric damage is useful for understanding the nature of optical materials under high-power laser irradiation.
在真空环境下利用紫外脉冲激光对熔石英元件表面进行了低于损伤阈值的辐照,通过X射线光电子能谱对激光诱导的表面氧空位进行了精细表征。研究结果表明:在10-3Pa的高真空环境下熔石英表面易受紫外激光激励形成低结合能的O1s(531 e V),这种非稳定结构在后续紫外脉冲激光辐照下会出现Si-O键断裂从而产生氧空位,氧空位产生的程度取决于激光脉冲能量、发次以及真空度,且对熔石英元件的抗损伤性能有显著的负面影响。
