热压载荷作用下气体检测光学窗口对激光传输影响

采用有限元方法研究了不同热压载荷作用下多组分气体原位激光检测系统的光学窗口变形分布情况,并根据热光效应计算得到光学窗口折射率分布。采用光线追迹法对比分析了氮气吹扫前后光学窗口折射率变化及变形对到达接收面的通光量和辐照度分布影响规律。此外,基于高温光学窗口激光透射测试平台开展了高温光学窗口对检测信号影响研究。结果表明:高温高压环境会使光学窗口折射率变化幅度增大及变形加剧,导致激光光路偏折引起透射光强损耗和探测信号条纹干涉;氮气吹扫可以有效改善激光传输条件,增加到达接收面的通光量,优化辐照分布,提高激光传输质量。

Influence of optical window for gas detection on laser transmission under thermal pressing loads

The finite element method was used to study the deformation distribution of the optical window of the multi-component gas in-situ laser detection system under different thermal pressing loads, and the refractive index distribution of the optical window was calculated according to the thermo-optic effect. The influence laws of the refractive index change and deformation of the optical window before and after nitrogen purging on the luminous flux and irradiance distribution reaching the receiving surface were compared and analyzed by ray tracing method. In addition, based on the laser transmission test platform of high-temperature optical window, the influence of high-temperature optical window on the detection signal was studied. The results show that the high-temperature and high-pressure environment will increase the refractive index change amplitude and deformation of the optical window, which resulting in the laser optical path deflection induced transmitted light intensity loss and probe signal fringe interference. The nitrogen purging can effectively improve the laser transmission conditions, increase the luminous flux reaching the receiving surface, optimize the irradiation distribution and improve the laser transmission quality.