Optical head and recording and/or reproducing apparatus

摘要

An optical head and a recording and/or reproducing apparatus employing the optical head, are disclosed in which variations in the amplitude and phase of the push-pull detected preformat signals, such as MSK modulated wobble signals which encode address information, are reduced.;Such variations occur because of variations in the phase relationship with the neighbouring tracks, since the interference from in-phase and out-of-phase reletionships is different. The beam from the in-phase relationship between neighbouring tracks contains a reflected beam and diffracted beams with a shift λ/(Tp·NA) and the beam from the out-of-phase relationship a reflected beam and diffracted beams with shifts λ/(Tp·NA) and λ/(2·Tp·NA).;The photodetector unit includes a first light receiving section (230b) and a second light receiving section (230c). Each of the first and second light receiving section receives the light of one of two light spot areas lying on both sides of a centre area, and the signal components from the diffracted light with a shift λ/(2·Tp·NA) generated in the centre area of the light spot may be removed and variation in the amplitude or phase of the push-pull signal reduced.