Patent ID: 7307927
Filing Date: 2007-12-11
Classification: G11B

Abstract:
1. A method for recording and reproducing an optical disk wherein a beam on an optical disk is focused using an optical pickup, a reflected beam from said optical disk is detected by a photodetector, a focusing error signal is detected from output signals of the photodetector, and a tracking error signal is detected by the push-pull method, the method comprising the steps of: detecting push-pull signals and reproduced information signals in a state of “in focus” and in a state of “out focus,” respectively; detecting a first spherical aberration error signal that varies depending on the amplitudes of said push-pull signals in the state of “in focus” and in the state of “out focus”; detecting a second spherical aberration error signal that varies depending on the amplitudes of said reproduced information signals in the state of “in focus” and in the state of “out focus”; and correcting the spherical aberration based on said first and second spherical aberration error signals.