| 摘要 |
PURPOSE:To detect the position of a lens without deteriorating frequency characteristics to the movement of the lens by providing a light quantity variation detecting means that varies the quantity of luminous flux which is emitted and reaches a photodetecting means according to the movement extent of the lens. CONSTITUTION:Divergent luminous flux emitter by the light source 27 is converted on one position through a convex lens 50 and the converged luminous flux is converged through a condenser lens 51 on a photodetector 30 for position detection, thereby detecting the quantity of the photodetection. A light shield member 52 is coupled integrally with a lens frame 31 where an object lens 17 is fixed is inserted into the convergence part according to the movement extent of the lens frame 31 to cut off the luminous flux, and transmitted luminous flux is guided to the photodetector 30 for position detection, so that the quantity of photodetection of the photodetector 30 for position detection varies. Consequently, the detection sensitivity to deviation of the objective lens 17 from a specific position is improved greatly. |
