Patent ID: 6418095
Filing Date: 2002-07-09
Classification: G11B

Abstract:
An optical information processing apparatus, comprising:an optical system for collecting a beam emitted by a light source onto an information memory medium; a light detector for generating a detection signal in accordance with a light amount of the beam reflected by the information memory medium; a signal processing section for processing the detection signal; and a correction section for correcting wave front aberration on the beam collected by the optical system, the wave front aberration being generated by an offset of an angle made by the beam collected by the optical system and the information memory medium from a prescribed angle, wherein: the information memory medium has a second pattern area including groove tracks having grooves, the groove tracks being arranged with a prescribed gap therebetween, NA>&lgr;/Gp where Gp is a distance between centers of two adjacent groove tracks, &lgr; is a wavelength of the beam emitted by the light source, and NA is a numerical aperture of a part of the optical system facing the information memory medium, the information memory medium further has a first pattern area including tracks having a mark and space array, the tracks being arranged adjacently to each other, the mark and space array having a mark and a space, the mark and space array in the first pattern area includes a first mark and space array and a second mark and space array, which are arranged to be away from a center of the groove tracks by a prescribed distance in a direction substantially perpendicular to the longitudinal direction of the tracks, the first pattern area and the second pattern area are alternately arranged on the information memory medium in a longitudinal direction of the tracks, and the detection signal includes a first detection signal and a second detection signal, the first detection signal is obtained by the light detector when the first pattern area is irradiated by the beam collected by the optical system, the second detection signal is obtained by the light detector when the second pattern area is irradiated by the beam collected by the optical system, and the signal processing section generates a first processing signal based on the first detection signal, generates a second processing signal based on the second detection signal, outputs one of the first processing signal and the second processing signal as a tracking error signal and outputs the other of the first processing signal and the second processing signal as an inclination detection signal.