Development of Integrated Multi-Station System to Precisely Detect and Mitigate Surface Damage on Fused Silica Optics

In high power laser facility, irreversible damage on fused silica optics, induced by laser irradiation or processing, seriously affects the service life of optics. Therefore, the work of inhibiting damage growth has been carried out in various countries. In our work, an integrated multi-station system is designed to detect and mitigate surface damage on fused silica. The process of processing fused silica optics include UV laser conditioning, surface damage detection and surface damage mitigation with CO₂ laser. UV laser conditioning pre-initiates surface damage on fused silica optics with the laser flux less than Laser-Induced Damage Threshold (LIDT). Images of surface damage acquired from camera are processed by improved global threshold segmentation algorithm to extract damage information. Finally, CO₂ laser is applied to process the damage with specific morphology to enhance the laser damage resistance. This integrated multi-station system saves the repeated optics installation time between the workstations with the positioning accuracy of 20 μm. Furthermore, the damage with diameter of 10 μm is mitigated to prolong service life of processed fused silica optics. The efficient and accurate integrated multi-station system is of great significance for off-line detecting and mitigating surface damage of fused silica optics in high power laser facility.