Confocal optical system aperture detector that measures a light quantity balance of light received to detect a position displacement, and a confocal optical system aperture position controller, an optical head and a position detecting method performing the same

Abstract

In a confocal optical system having a light source, a first focusing means, a second focusing means, an aperture, and a detectorincluding a plurality of light reception regions, a position displacement is detected by detecting an intensity distribution of an image caused by a position displacement between a focusing spot of the second focusing meansand the aperture, by the detector. Further, the position displacement is corrected by controlling the aperture position using driving meansand control means. Also, a position displacement of the aperturein the optical axis direction is detected and corrected on the basis of a change in an output of the detectorby oscillating the aperturein the optical axis direction.