| 摘要 |
PURPOSE:To enable provision of an inexpensive focusing device by using one photodetector, and scanning the same by moving a slit on the front surface of said photodetector. CONSTITUTION:A mask member 5 is formed by juxtaposing many slit-shaped thin film liquid crystals 6 with the long sides thereof brought into contact with each other in the directions toward Z, infinity from reference positions Z, O. Such member is used as a movable window through which the light reflected from an object passes. If the object is scanned from the side of the positions Z, O with the movable window of the mask member 5, the output voltage from a photodetection part 4 exceeds a noise level and a peak voltage is outputted therefrom when the LCD6 corresponding to the imaging positions A', B', C' of the object turns on. The output voltage from the part 4 is amplified by a head amplifier 8 and is outputted as the peak voltage alone from a peak detector 9. The imaging position of the object, that is, the information on the distance of the object from a camera is obtd. |
