可在线应用的大口径溶胶-凝胶膜光学元件激光清洗工艺研究(特邀)

In-situ laser cleaning of large-aperture optical components with sol-gel film(invited)

在高功率激光装置中,光学元件表面的污染物会降低光束质量甚诱导光学元件损伤。针对装置中受污染的镀有SiO2溶胶-凝胶增透膜的大口径真空隔离片(430 mm×430 mm),使用波长为355 nm的Nd:YAG脉冲激光器模拟在线激光清洗实验。实验中采用了单发次激光干式清洗与气流置换系统辅助的激光清洗系统,研究了关键特征参数对激光在线清洗效果的影响规律,获得了可用于激光在线清洗的工艺参数。光学元件的处理采用光学显微镜、暗场成像法表征以及图像处理软件分析。实验结果表明,激光在线清洗光学元件存在最佳工艺窗口。通过气流置换辅助的激光清洗方法后,相较于单纯的单发干式激光清洗,激光清洗能力有大幅提升。因此,气流置换系统辅助单发激光清洗能有效提高其清洗能力,为高功率激光装置中大口径光学元件表面污染物在线去除提供了一种有效手段。

In high-power laser facilities, contaminants on the surface of optical components can reduce beam quality and even induce damage to optical components. For the contaminated large-aperture vacuum separator(430 mm×430 mm) coated with SiO2sol-gel antireflection film in the facility, a Nd:YAG pulsed laser with a wavelength of 355 nm was performed in laser cleaning experiment. The experiment adopted a single-shot laser dry cleaning and a laser cleaning system assisted by an airflow replacement system. The influence of key characteristic parameters on in-situ laser cleaning was studied, and the process parameters that could be used for laser in-situ laser cleaning were obtained. The processing of optical elements was characterized by microscope,dark field imaging and image processing software analysis. The experimental results suggest that there is an optimal process window for laser in-situ cleaning of optical components. After the laser cleaning method assisted by airflow replacement, the laser cleaning ability is greatly improved compared with the simple single-shot dry laser cleaning. Therefore, the single-shot laser cleaning assisted by the airflow displacement system can effectively improve its cleaning ability and provide an effective means for the in-situ removal of contaminants on the surface of large-aperture optical components in high-power laser facilities.