| 摘要 |
PURPOSE:To detect precisely a focusing state with high accuracy by projecting the exit pupil of imaging optical system on two photodetector arrays which are disposed in parallel and in a prescribed way, determining the evaluation values for a lateral deviation in accordance with the outputs of the respective arrays and adding the same. CONSTITUTION:Two photodetector arrays 11, 12 are disposed in parallel on a plane intersecting orthogonally the optical axis of an imaging optical system. When the photodetector which receives one incident light is designated as A and a photodetector which receives the other incident light as B, the photodetectors are so arranged that A, B are arrayed alternately in each array, so that the photodetectors in both arrays receive the incident light in opposite directions in the direction intersecting the array direction as well. The output of the n-th photodetector Ab which receives one incident light is designated as an and the output of the n-th photodetector Bn which receives the other incident light as bn and the respective evaluation values F1, F2 indicating the lateral deviation of the image are determined by using F=SIGMAn(SIGMAan+1-bnSIGMA-SIGMAan-bnSIGMA). The focusing state of the imaging optical system is detected exactly with high accuracy by -F1+ F2. |
