Optical disk device

Abstract

This invention provides an optical disk device comprising an optical pick-up being structured to irradiate light beams onto an optical disk through an objective lens unit, receive the light beams reflected from the optical disk by a two-divided light-receiving element, convert amounts of light received by each segment of the light-receiving element into electrical outputs, and detect differential signals between the electrical outputs, a spherical aberration adjustment device for changing spherical aberration of light emitted from the objective lens, a detection device for detecting control signals for the adjustment device to minimize asymmetry of the deterioration degree of the differential signal amplitude detected when a light beam is defocused at any desired position on the radius of the optical disk, and a memory device for storing the control signals corresponding to the positions on the radius. The optical disk device performs recording and reproducing by controlling the spherical aberration adjustment device based on the control signals for the positions on the radius stored in the memory device.