Patent ID: 7327661
Filing Date: 2008-02-05
Classification: G11B

Abstract:
1. An optical pickup comprising: a laser light source; a beam separation means which separates a laser beam emitted by the laser light source into at least three beams; a converging optical system which converges the three beams and forms three separate convergence spots on a recording surface of an optical information record medium; and a photodetector which is placed to receive each of reflected beams of the three convergence spots from the optical information record medium with a photoreceptor surface divided into at least two faces, wherein: the beam separation means is divided into at least three areas, first through third areas, each of which has prescribed periodic structure, and the first area is placed between the second and third areas, and the second area has periodic structure that is shifted from that of the first area by approximately 90° in the phase of the periodic structure, and the third area has periodic structure that is shifted from that of the second area by approximately 180° in the phase of the periodic structure.