New ultra-precision polishing techniques of glass BK-7 optical plate

The optical plate made of glass BK-7 as a measuring base, is widely used in modern optical industry. In conventional optical glass component polishing, the pitch polisher has long been found satisfactory in obtaining both high quality and high accuracy. Pitch having delayed elasticity, however, it shows a quasi-rigid property that does not respond to an instantaneous force as polishing advances. In pitch polishing, highly sophisticated techniques are required to obtain superior mirror-like surfaces and special configuration accuracy. In order to satisfy these requirements, new polishing techniques with the conditioning ring-type polishing machine, the pitch K3 polisher with 4 mesh grooves on its surface, and fine SiO2 powders are proposed in this study. The final surface roughness of the polished glass BK-7 plate is less than I nm. The machining process and characteristics are also indicated in this study.