| 摘要 |
PURPOSE:To easily form required plate-shaped plastic optical parts with a high precision by integrally forming a flange part, which surrounds plate-shaped optical parts body having a required optical surface and is higher than the optical surface, in the outside peripheral part of this optical parts body as one body. CONSTITUTION:A diffraction grating plate consists of a disk-shaped body 10 and a flange part 11 which is integrally formed in the outside peripheral part of the body 10 as one body to surround the body 10. The flange part 11 surrounding the outside peripheral part of the body 10 has a height (h) higher than that of the optical surface of the body 10 and has a thickness as 1.1-2 times as wide as a thickness (t) of the body 10 and is projected onto the optical surface. An inside peripheral surface 18 of the flange part 11 is formed into a trimming die shape having an angle >=1 deg. of inclination so that molded product can be easily taken out from a mold in case of injection molding.
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