Analysis of subsurface damage during fabrication process and its removal

Abstract

Subsurface damage (SSD) in optical components is known to play an important role in restricting the high fluence operation in high power laser systems. Subsurface damage appears inevitably during the shaping, grinding, and polishing process, which are essential in the production of defect-free optical components. In order to obtain expectant optical components, we need to obtain the distribution and character of fractures in the subsurface region introduced during fabrication process, and therefore investigate the positions and depths of the SSDs in the processed optical components accurately and remove them ultimately. In this study, we made several groups of samples of fused silica with different surface roughness, and manage to detect the positions and depths of the SSDs via Total Internal Reflectance Microscopy (TIRM). The lateral distribution of the SSDs is obtained. The surface etched in fluoride solution exposing subsurface damage is also observed. The character of fractures in the subsurface region is discussed.