Multimodal surface defect detection of fused silica components based on confocal time-resolved photoluminescence microscopy

Surface defects on fused silica components are susceptible to damage under high-fluence ultraviolet pulse laser irradiation, which is one of the key factors limiting the improvement of the laser damage resistance. However, there is still an absence of intuitive non-destructive evaluation methods for the laser damage resistance of surface defects. In this paper, we have developed a multimodal surface defect detection system. Detection and localization of defects are achieved via a low-magnification dark-field scattering imaging module with annular illumination. For a specific defect, the morphology and size are observed through a high-magnification bright-field imaging module. The ultra-fast fluorescence intensity and lifetime distribution of the defect are obtained based on a fluorescence lifetime imaging module. The system is capable of multimodal detection of surface defects on fused silica components, and brittle defects can be effectively identified simultaneously. To some extent, the laser absorption capacity and the laser damage resistance of defects can be revealed, providing new ideas for the performance evaluation of optical components in high-power laser devices and the optimization of the manufacturing process.