Patent ID: 8488425
Filing Date: 2013-07-16
Classification: G11B

Abstract:
1. An optical pickup device comprising: a laser diode which emits laser light; an objective lens which irradiates an optical beam emitted from the laser diode on an optical disc having at least a first recording layer and a second recording layer; a grating which branches an optical beam reflected by an information recording layer on the optical disc into a plurality of optical beams by a plurality of regions in the grating; and a photodetector having a plurality of light receiving parts which detect the optical beams branched by the plurality of regions in the grating, wherein: the photodetector has one light receiving part which detects a reproduction signal, and in case of focusing on the first recording layer as an intended information recording layer of the optical disc, zero-th order grating diffracted light of the grating reflected by the first and second recording layers is irradiated only to the one light receiving part which detects the reproduction signal among the light receiving parts.