| 摘要 |
PURPOSE:To utilize light beams which are radiated while a shutter is closed, by installing a reflector on the surface of a light source side of the shutter for shading the light beams, and providing an optical fiber on the position for photodetecting the reflected rays. CONSTITUTION:When a reflector driving mechanism 25 is energized in a state that a shutter 12 has been closed, a turning plate 20 is turned and is positioned at the first operating position, and a light beam reflected by the first plane mirror 3 is led by an optical fiber 29A through the first reflector 23A and the first photodetecting part 30A. When a switching mechanism 28 is further energized, the turning plate 20 is further turned, and the reflector 23A gets out of the optical path, but the second reflector 23B cuts off the optical path, a light beam is reflected by the second photodetecting part 30B, passes through this photodetecting part 30B, and is led by the second optical fiber 29B. According to such a constitution, a light beam from a light source is fetched from the first and second optical fibers 29A, 29B even while the shutter is closed. |
