| 摘要 |
PURPOSE:To facilitate the fabrication and inspection of an optical system for a short time by a construction wherein a mask arranged near the curvature center of the optical system and provided with the penetration holes in close proximity to and afar from the axis, and a screen placed in front of the mask, are arranged on and the same optical axis. CONSTITUTION:A Schmidt lens 10 for correcting spherical aberration caused by a mirror 6 is arranged in front of a face plate 1 in order to form an image reflected from, enlarged by the mirror 6 and coorected by the Schmidt lens 10 on a screen 11. A mask 12 is arranged in close proximity to the Schmidt lens 10 to selectively transmit light so as to screen the enlarged image light, the mask 12 comprising a penetration hole 12a for transmitting light near the optical axis of the mirror 6 and another penetration hole 12b for transmitting light in a region separated from the optical axis. These penetration holes 12a, 12b are made in a concentric circular form. In so doing, a distance of projection is readily detected and, in addition, the fabrication, adjustment and inspection of an optical system are easily carried out. |
