| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate for a plastic Fresnel lens which is hard to warp even made thin without causing uneven brightness and irregular images and not degrading workability when machining the lens. SOLUTION: The substrate for the Fresnel lens is a sheet made of a synthetic resin 0.1-1.0 mm thick and folded at least on one side. COPYRIGHT: (C)2007,JPO&INPIT
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