Patent ID: 7280449
Filing Date: 2007-10-09
Classification: G11B

Abstract:
1. An optical head comprising: a light source; an objective lens configured to condense a light beam, radiated from said light source, to a recording track of said optical recording medium; a photodetector configured to receive the light beam reflected back from said recording track; and said photodetector includes a first light receiving section, a second light receiving section, and an interval area between said first and second light receiving sections, wherein a track pitch Tp of said optical recording medium, the wavelength λ of the light beam radiated from said light source, and the numerical aperture NA of said objective lens satisfies the condition λ/(Tp·NA)≧4/3, said first light receiving section detects the light of one of two spot areas lying on both sides at a distance λ/(Tp·NA) from a center area of a light spot of said reflected light beam passing through the center of the light spot for extending along the length of said recording track, said second light receiving section detects the light of the other of said two light spot areas, said interval area detects the light corresponding to the width of said center area of said light spot, and said photodetector is configured to generate a push pull signal without including the detected light corresponding to the width of said center area of said light spot.