| 摘要 |
PURPOSE:To perform high-precision focusing detector through a simple constitution, by using an optical position detector as a photoelectric converting element, and detecting the relative position relation of object images formed of pieces of luminous flux passing through paths different in image-formation optical diameters. CONSTITUTION:A pupil splitter 21 is equipped with light transmission parts 21a and 21b which are controlled into a transparent state by using an electrochromic element, etc. A linear optical position detector 23 is arranged at the focal point of an image forming lens 22 and the pieces of luminous flux passing through the light transmission parts 21a and 21b form an image on the optical position detector 23 through the lens 22. Output currents IA and IB from two electrodes of the detector 23 are amplified and processed by a subtracter 25 and an adder 25 and a circuit 27 finds the center of gravity of the light, i.e. (IA-IB)/(IA+IB); and a driving circuit 28 while controlling the splitter 21 outputs a pulse to a comparator 30, which makes a comparison with a detection signal to discriminate between a front and a rear focus. |
