高功率激光装置大口径光学元件侧面清洗实验

针对高功率激光装置内部最易产生受激布里渊散射(SBS)效应的大口径取样光栅(BSG)元件，测试了经过化学刻蚀、紫外激光清洗作用处理后，大口径光学元件BSG侧面在355 nm激光辐照下的损伤阈值、损伤形态以及产生的石英颗粒气溶胶对环境污染程度的分析。结果表明:经过化学刻蚀，BSG侧面的损伤阈值提高78%，基本与通光面的损伤阈值相当，而经过紫外激光处理后的损伤阈值提升不高，仅为通光面损伤阈值的56%。侧面对比分析了相同激光能量辐照下样片侧面产生的气溶胶污染状况，结果表明紫外激光处理同样可以提高光学元件侧面产生污染物的阈值，且对光学元件性能没有影响。通过微观形貌和对通光口径影响分析表明，紫外激光清洗处理比化学刻蚀具有更好的安全性和适用性。

Experiment on cleaning side of large-aperture optics in high power laser system

The laser induced damage threshold (LIDT) and the particle contaminations of the large-aperture optics such as beam sampling grating (BSG) which is likely to generate stimulated Brillouin scattering, were measured after chemical etching and ultraviolet (UV) laser cleaning, with the BSG side under the radiation of 355 nm laser. The results show that the LIDT of the BSG side increases by 78% after chemical etching, which is almost equal to that of light pass surface, but it is only about 56% after UV laser cleaning. By comparing the particle contaminations coming from the side of the optics in two ways, it is found that the UV laser cleaning can also improve the laser threshold for the particle contamination generating, and has little influence on the optics performance. Also, we prove that the UV laser cleaning has a better security and applicability than the chemical etching through the analysis of morphologies and the influence of optical clear aperture.