Cerium oxide polishing to improve uniformity of diffraction efficiencyof beam sampling grating

As one element of final assembly in high-power laser systems, beam sampling grating (BSG) is a fused silica grating with shallow depths. In order to improve the uniformity of diffraction efficiency of a BSG, a classical chemical mechanical polishing technique of fused silica, with CeO2 as the polishing material, is proposed for BSG to modify its profile and efficiency. With this method, the efficiency root mean square of a BSG with an aperture of 430 mm430 mm can be reduced from nearly 30% to less than 5%, which shows that the CeO2 polishing is a feasible and effective method to improve the efficiency uniformity of BSG.