Potassium dihydrogen phosphate (KDP) crystals are essential components used in the high power laser applications. Its properties will affect the output power and quality of laser beam directly. To improve the laser-induced damage threshold (LIDT) of KDP crystal, this paper investigated the influence of ion beam figuring(IBF) technology on the laser damage properties of KDP crystal machined by single point diamond turning(SPDT). Firstly, the surface quality and photo-thermal absorption performance of samples were measured after turning and ion beam figuring. Then, the LIDT of crystal of different processing conditions were measured by R-on-1 test method. Finally, the mechanisms that ion beam figuring could improve the LIDT were analyzed and discussed.The experiment results show that ion beam figuring can reduce surface roughness,improve the surface quality as well as lower the absorption of KDP crystal elements, which contribute to increase the laser damage resistance of KDP crystals obviously.
Nd doped phosphate glass is widely used as gain media in high power laser system. It is traditionally polished with the annular polishing technology. The edge effect is inevitable in annular polishing process and it results in the low manufacturing efficiency. Ion Beam Figuring (IBF) is a highly deterministic, non-contact method for the ultra-precision optics fabrication. So the edge effect is avoided. Nanometer and sub-nanometer precision is realizable in IBF. In this paper, Nd doped phosphate glass was polished with IBF, and the evolvement of surface roughness was emphasized. The roughness of surface polished with ion beam at normal and oblique incidence was researched. The oblique incident angle was 45°. The surface roughness was measured with the white light interferometer. No evident change was observed. This means that the pre-finish roughness can be preserved in IBF. The results denote that IBF is a feasible method to correct the contour errors of Nd doped phosphate glass, and the roughness will not be coarsened.