Research on subsurface damages of fused quartz by different grinding methods

Fused quartz material demonstrates strong ultraviolet light transmission and resistance to laser damage, making it the primary choice for selecting large-diameter optical components in high-power laser systems. The challenge now lies in achieving low damages and high resistance to laser damage. A significant number of large-scale (with characteristic depths ranging from 10μm to 100μm) Sub Surface Damages (SSD) are generated in grinding stage, requiring substantial material removal during the subsequent polishing stage to ensure the damage resistance performance of the components. Therefore, it is crucial to study damage control in grinding stage for achieving optimal subsurface quality in optical components. This paper focuses on the processing state of fused quartz components under various grinding processes. Initially, a comparative experiment is conducted using loose abrasive and bonded abrasive with the same grain size (6μm), followed by an examination of three different grain sizes (6μm, 9μm, 20μm) of bonded abrasive grinding processes. After grinding, all processed samples are appropriately etched to reveal subsurface damages. The damage distribution and morphological information of the experimental samples are observed using optical microscopy and scanning electron microscopy. The value of surface roughness (Rz) of the fused quartz samples is measured using white light interferometry, and the corresponding SSD is calculated using the empirical formula of Kun Xiao. The findings indicate that the bonded abrasive processed samples exhibit higher removal efficiency and smaller SSD compared to the loose abrasive samples.