OPTICAL PICKUP AND OPTICAL RECORDING AND PLAYBACK DEVICE

摘要

The present invention is provided with a laser light source which emits an optical beam, a diffractive element for diffracting the optical beam so as to branch into a plurality of beams of diffracted light that include zeroth-order diffracted light and diffracted light other than the zeroth-order diffracted light, a lens which collects the plurality of beams of diffracted light upon an optical recording medium, and a photodetector which receives at least a portion of the plurality of beams of diffracted light which have been reflected from the optical recording medium. The diffractive element has a first diffraction grating area and a second diffraction grating area which differ in orientation and pitch of the grating vectors. The first diffraction grating area is configured so that light spots of the diffracted light other than the zeroth-order diffracted light are positioned upon the same track as the light spots of the zeroth-order diffracted light, and the second diffraction grating area is configured so that the light spots of the diffracted light other than the zeroth-order diffracted light are positioned at one side of the track or spread to both sides thereof.