Abstract: An optical head for optical storage, having an optical scanner for scanning a laser beam in a recording region, an objective lens of large aperture for collecting all scanned laser beams, and a method for detecting and correcting the focus error and tracking error, a light source and photodetector, in which the objective lens is fixedly set up and the photodetector is placed at the conjugate point of the focal point of laser beam on the recording media. The laser beams reflected from the media are always collected at the center of photodetector, out of relation to the scan angle, thereby reading uniformly the information from the recording media and it is not necessary to move the objective lens. Therefore, access time can be very short.