Patent ID: 7184384
Filing Date: 2007-02-27
Classification: G11B

Abstract:
1. An optical pickup comprising: a light emitting element; condensing means for condensing on an optical recording medium an optical beam emitted from the light emitting element; an optical diffraction element, provided between the light emitting element and the condensing means, for dividing the optical beam from the light emitting element into three or more beams including a main beam and sub beams; and an optical detection system with a light receiving element which receives reflected light from the optical recording medium by dividing the reflected light by a dividing line that substantially coincides with a track direction of the optical recording medium, wherein: the optical diffraction element includes first and second grating patterns with grooves and lands that are formed along a direction substantially perpendicular to the track direction of the optical recording medium, the grooves and lands of the first grating pattern and the grooves and lands of the second grating pattern being shifted from each other by a predetermined pitch in the direction the first and second grating patterns are formed, and the first and second grating patterns being formed in the shape of a band and being tilted in a first region and a second region that adjoin in a direction substantially perpendicular to the track direction.