Patent ID: 9361927
Filing Date: 2016-06-07
CPC Classification: G02B,G11B

Claim Text:
1. An optical pickup for, while recording data onto a track of an optical storage medium, reading data that has been recorded on the track, comprising: a light source for emitting a light beam; a diffraction element for separating the light beam emitted from the light source into a plurality of light beams including a write main beam and a read sub-beam; an objective lens configured to converge the main beam and the sub-beam onto a same track on the optical storage medium; a wavelength plate disposed on an optical path from the diffraction element to the optical storage medium, the wavelength plate being designed so that a polarization direction of light which is incident from the diffraction element onto the wavelength plate is orthogonal to a polarization direction of light reflected from the optical storage medium and transmitted through the wavelength plate; a polarization hologram element having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0 an actuator for integrally driving the objective lens and the polarization hologram element for focus control and tracking control; and a photodetector configured to detect a light beam reflected from the optical storage medium and diffracted by the polarization hologram element, the photodetector generating an RF signal from a detection result concerning a 0 wherein the plurality of diffraction regions of the polarization hologram element are four regions divided around a center which is a point traveled by a central portion of the main beam, the division being made by a straight line in a same direction as a track of the optical storage medium and a straight line in a perpendicular direction to the track.