Patent ID: 7310297

Claim:
An optical disk device, comprising: an optical pick-up being structured to irradiate light beams onto an optical disk through an objective lens, 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 two-divided 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 of the optical pick-up; a detection device for detecting asymmetry of deterioration degree of the differential signal detected when a light beam is defocused at any desired position on the radius of the optical disk with respect to the best-focus position where the differential signal is maximized; a detection device for detecting control signals for the spherical aberration adjustment device; and a memory device for storing data constellation of the control signals corresponding to positions on the radius of the disk to minimize the asymmetry of the deterioration degree of the differential signals, wherein the optical disk device performs recording and reproducing by controlling the spherical aberration adjustment device based on the data constellation of the control signals for the positions on the radius stored in the memory device.