| 摘要 |
PURPOSE:To correctly align the optical axis of a lens and the central point of photodetectors by using the four photodetectors or photodetector groups in symmetrical positions with respect to the central point of a photodetector array. CONSTITUTION:A photodetector array 1 is constituted of multiple photodetectors 100,101,102.... Spot light 2 of an area smaller than the area encircled by these photodetectors A-D is irradiated to the four photodetectors A-D which are in symmetrical positions with respect to the central point O of the array 1. When the central point O of the array 1 and the optical axis of the spot light 2 are misalgned, the output signals of the photodetectors A-D assume different values. The output signals of these photodetectors are compared and the stage is moved to the position where all become equal. |
