Subsurface damage layer of bulk single-crystal potassium dihydrogen phosphate (KDP) after SPDT: studied by the grazing incidence X-ray diffraction technique

Abstract

This work proposes a novel way of the subsurface damage layer characterization for bulk single-crystal optical material, based on the X-ray grazing incidence technique (GIXRD). The result shows that the subsurface damage layer of bulk single-crystal potassium dihydrogen phosphate (KDP) mainly consists of polycrystalline KDP and bulk single-crystal matrix after single-point diamond turning (SPDT). Meanwhile, it is found that the polycrystalline KDP presents some kinds of preferred orientations, which depend on the SPDT surfaces and SPDT track u . For example, the polycrystalline texture of (010) SPDT surface is p (103)// u and p (204)// u , while the polycrystalline texture of (111), I-type and II-type SPDT surfaces are p (312)// u , p (332)// u and p (202)// u , respectively. These findings allow us to further understand the subsurface damage layer of bulk single-crystal KDP after SPDT.