| 摘要 |
PURPOSE:To easily and rapidly detect the inclination of an optical axis, by detecting the inclination of the optical axis from the radius of a ring image formed on a screen by the reflected light from the mirror surface of a tubular jig of which the inside is the mirror surface. CONSTITUTION:A tubular jig 1 having a mirror surface provided to the inside thereof is inserted so that the center axis thereof coincides with an ideal optical axis 2 and a screen 3 having a proper size is placed on the extended line of said axis. Whereupon, when an actual optical axis 4 is inclined from the ideal optical axis 2, a hot image (A) due to the light passing through the part of an oblique line A and a ring image (B) due to the partial reflected light of an oblique line B are projected to the screen 3. When the inclination of the optical axis is large, the radius of a ring becomes large and, when small, the radius of the ring becomes small. When the actual optical axis coincides with the ideal optical axis, the ring image is lost and only a spot image is present. By this method, the inclination of the optical axis can be easily detected.
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