| 摘要 |
PURPOSE:To discriminate and set the direction of the optical axis of a curved surface mirror easily and accurately by providing a plane on a part of the mirror body and irradiating this plane with a laser beam or the like and detecting its reflected light. CONSTITUTION:A plane 5 is cut and worked in a reflecting part 3 of a mirror body 1 while leaving a flat surface 4 on its outside circumferential edge as it is, and a step is formed between the plane 5 and the flat surface 4 vertically to an optical axis. This step is a closed curved surface (b) which is parallel with the optical axis and is shaped into a concentric circle. When the plane 5 is used to discriminate the direction of the optical axis 7, a laser beam L is irradiated to the plane 5, and a normal 9 vertical to the plane 5 is obtained in accordance with a reflection angle alpha of the laser beam on the plane 5. Since the normal 9 is a line parallel with the optical axis 7, this operation is performed in several positions of the plane 5 to discriminate the direction of the optical axis 7. |
