| 摘要 |
PURPOSE:To subdivide and equalize a crystal particle diameter of a mirror surface part, and to improve the characteristics of the mirror surface of a reflection factor and a scattered light intensity, etc. by forming a stepped part on the whole periphery of the vicinity on the outside periphery which becomes the mirror surface part, and performing the shearing and the annealing. CONSTITUTION:A stepped part 2 whose width is narrow is formed by compressing a base material by plastic working, on the whole periphery of the vicinity on the outside periphery which becomes a mirror surface part of a rotary polygon mirror 1. In this compression process, a crystal particle diameter of the base material of the rotary polygon mirror is recrystallized, and subdivided and equalized. That is to say, by forming a stepped shape by the compression, an optimum draft for obtaining a characteristic of a mirror surface of the rotary polygon mirror can be selected. Also, a mirror surface part 3 of the rotary polygon mirror 1 is formed by shearing, a shearing surface of the time of punching by a press generates a plastic flow of a crystal organization by a shearing stress of the time of punching, and becomes small. Thereafter, annealing is performed to the mirror surface part 3, and the crystal particle diameter of the mirror surface part 3 is subdivided and also equalized, and a base material of the rotary polygon mirror can be obtained. In this way, the characteristic of the mirror surface is improved, and the working time of the time of super-precise cutting can be shortened. |
