Patent ID: 8937855
Filing Date: 2015-01-20
Classification: G11B

Abstract:
1. A holographic optical pickup device for recording an information signal by irradiating an optical information recording medium with a reference beam and a signal beam to form a hologram, or reproducing the information signal by irradiating the hologram on the optical information recording medium with the reference beam, comprising: a light source for emitting a light beam; a split element for splitting the light beam emitted from the light source into the signal beam and the reference beam; an optical axis split element for splitting the reference beam into two light beams in different propagation directions having polarized states substantially orthogonal to each other; an angular variable element for changing an incident angle of the reference beam split into the two light beams which irradiates the optical information recording medium; a spatial light modulator for adding the information signal to the signal beam; an objective lens for irradiating the optical information recording medium with the signal beam to which the information signal is added; an image sensor for detecting a diffracted beam generated from a recorded region when irradiating the optical information recording medium with the reference beam split into the two light beams; and a photodetector for detecting the diffracted beam generated from the recorded region when irradiating the optical information recording medium with the reference beam split into the two light beams, wherein an angular error signal is generated for controlling the angular variable element using the signal detected by the photodetector.