| 摘要 |
PURPOSE:To obtain a polygonal mirror having high accuracy in a short period of time by providing an outside circumferential ring, which consists of a synthetic resin and has polygonal planes on the outside peripheral face to the outside circumference of a circular or polygonal metallic core and providing a metallic specular surface film to the planes thereof. CONSTITUTION:The polygonal mirror 7 has the ring 14 having the polygonal outside circumferential planes 13a-13f made of a synthetic resin on the outside circumference of the circular metallic core 12 and the metallic specular surface film 15 is deposited by evaporation thereon. The resin part exists in the min. required part. i.e., only on the outside circumferential ring 14 according to this constitution. The dimensional changes by the change in temp. and humidity, the deformation of the resin is suppressed at the time of high-speed rotation by a motor 8. The performance equiv. to the performance of the conventional polygonal mirror made of glass or Al is thus obtd. and the time for production is shortened. |
