| 摘要 |
A lens has a concave shape or a convex shape in either vertical cross section or transverse cross section. Thereby light passing through the lens is largely refracted and the interior is harder to be seen even if a prism is not formed. As a result, there is no need to give a finish more than optical performance required for reflection to the front surface of the reflecting surface of a reflector, which is for the purpose of enhancement of its appearance, and thereby the machining work is simpler than the conventional way. Further, since the lens has a flat shape in either vertical cross section or transverse cross section, the lens is easily polished when it is made of glass, which is excellent in manufacture of the lens.
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