| 摘要 |
PURPOSE:To compensate the fluctuation of a movable part by rotating a parallel plate along an axis perpendicularly to an incident optical axis and shifting the optical axis. CONSTITUTION:An auxiliary beam 13 is made incident in a 2-split photodetector 31 of a movable part 10 from a stationary optical system 9 and if the moving axis of the movable part 10 and the optical axis of the parallel light 11 are deviated, the deviation between the moving axis and the optical axis, that is, the fluctuation of the movable part 10 is detected by the fluctuation of the difference of outputs of the detectors of the 2-split photodetector 31. Thus, a current flowing to a coil 23 of an optical axis shift actuator of the stationary optical system 9 is controlled to tilt the parallel glass plate 22, thereby shifting the optical axis of the parallel light 11 (radiated light) in parallel. Thus, the fluctuation of the movable part 10 is compensated. |
