| 摘要 |
PURPOSE:To detect a position with high accuracy, by providing a filter means electrically performing filtering operation in correspondence to the optical data of specific distribution among the optical data from the pattern generated on the pupil surface of an objective optical system. CONSTITUTION:The pupil ep of a projection lens 1 is set so as to be made conjugate with the light receiving surface of an image pickup element 14. The image signal PS from the element 14 is digitalized at every photoelectric signal level of each pixel by a buffer circuit 21 and stored as the luminous intensity distribution of one picture in a pixel unit. Next, an image filter circuit 22 inputs the image data PS' from the circuit 21 to apply an electrical mask to the picked up picture. The shape of this mask is indicated from a main control part 20 and can take an arbitrary shape. This masking may be performed by providing a mask circuit preliminarily storing the mask as the digital 1- or 0-bit pattern corresponding to the position of each pixel and taking AND with a digital value 0 with respect to the pixel to be masked. By this method, the pupil image having an arbitrary shape can be extracted and an eclipse is not substantially generated. |
