An edge chipping reducing process for grinding SiC segmented mirrors using powder mixture filler

The integrity of surface is one of the most important factors affecting the performance of an optical mirror. However, edge chipping is easy to appear near the gaps when grinding segmented mirrors and seriously reduces the quality. One of the solutions is filling the gaps to adjust the stress field. However, limited by the gap size and filler material, filler with single material cannot meet the further requirements for the quality of the mirror. Therefore, a method for suppressing edge chipping using powder mixture filler is proposed. Theoretical calculation combined with simulation reveals the variation of stress wave propagation when powder mixture filler is used. The edge chipping area in scratching tests shows a consistent trend with theoretical prediction. Compared with filler using single material, the using of powder mixture filler decreases the edge chipping area by up to 84.1%.