| 摘要 |
PURPOSE:To make possible rapid focusing by forming the optical image of the object on the surface formed by multiple photoelectric transducers and maximizing the peak-to-peak value of the electric signal corresponding to its brightness. CONSTITUTION:The lightness difference of the image A whose focus is matched is large but the lightness difference of the image B whose focus is not matched becomes small. The focus matching device 11 which makes use of this consists of an optical system 13, photoelectric transducer 14, control unit 15, drive mechanism 16, etc. The optical image of the object 3 is converted to the electric signal corresponding to its lightness by each photoelectric transducer 24 and this signal is output. This signal is input to a control circuit 15 and its peak-to-peak value is obtained by the specified circuits. Here, the point where the maximum value of the peak-to-peak values is obtainable is obtained by moving the optical system 13 certain times and this point is judged to be the completion of focus matching. Thereby, the width of the target 3 may be obtained through required computation with a measuring device 12. |
