It mainly includes ultra precision turning, mirror grinding and grinding. In ultra precision lathe, micro turning is carried out with single crystal diamond turning tool after fine grinding. The cutting thickness is only about 1 micron. It is often used to process high precision and smooth surface parts of non-ferrous metal materials, such as spherical, aspheric and flat mirrors. For example, the aspheric mirror with a diameter of 800mm used in nuclear fusion equipment can be processed with a maximum accuracy of 0.1 μ m and a surface roughness of rz0.05 μm.