Analysis of transmission characteristics of high power laser output optical window seal assembly

Sealing design is an effective way to prevent pollution of high power laser. The thermal stress and installation distortion of sealed optical window seriously affect the quality of laser beam. Based on the design scheme of glueless welding seal, this paper fully considering the material, absorption rate and welding layer interaction of the optical window and the base, combined with the finite element simulation method, the distortion of the sapphire and fused silica optical window surface caused by temperature drift and the installation stress was calculated. through the optimization and simulation of the V-shaped flexible release form of the installation stress, the physical model of the optimal design is obtained. Then, the temperature field, deformation and refractive index distribution of the optical window assembly is analyzed during the TEM₀₀ mode Gaussian beam lasing process and the effect of optical window surface distortion, defocusing amount and beam quality degradation with lasting time is calculated. At last, the influence of the change of the internal and external pressure difference is calculated. The results show that the leakage rate after welding is better than 10^-12Pa·m³/s, RMS of the mounting surface accuracy is 0.013 &lambda;. The laser power is 10kw and the light lasting time is 120s, the laser beam quality degradation rate <i>&beta;</i> &lt; 1.1, the relax meets the system requirements. The research results provide an important reference for the design, simulation analysis, laser transmission beam quality control and correction of high-power laser anti-pollution and sealed light window components.