Patent ID: 8520486
Filing Date: 2013-08-27
Classification: G11B

Abstract:
1. An optical pickup device that irradiates an optical disc with laser light and detects light reflected from the optical disc, comprising: a laser diode which emits a light beam of laser light; a polarized beam splitter which splits the light beam emitted from the laser diode into a first light beam and a second light beam and synthesizes signal light obtained from the first light beam with reference light obtained from the second light beam; an objective lens which irradiates the optical disc with the first light beam to obtain the signal light; a reflection element which reflects the second light beam with no irradiation of the optical disc with the second light beam to obtain the reference light; a phase difference forming unit which separates the light beam synthesized by the polarized beam splitter into a plurality of light beams and affords different phase differences to the signal light and the reference light included in each of the light beams; and a common detector including a plurality of light receiving parts which receives the plurality of separated light beams, wherein, the phase difference forming unit includes a grating, a divided wave plate and a polarization grating, and the divided wave plate has a plurality of regions, each region affords different phase differences to the incident light beams.