Patent ID: 6487016
Filing Date: 2002-11-26
Classification: G11B

Abstract:
An optical head comprising:a first grating element and a second grating element arranged in that order in a light path between a light source and an objective lens, the light path including an outgoing light path and a return light path; a light path alteration member for deflecting light arranged in the light path between said light source and said first grating element, the lowest point of said objective lens being lower than the highest position of light which is emitted from said light source and which is incident on said light path alteration member in a height direction from said objective lens toward an optical recording medium of the optical head, or in the light path between said second grating element and said objective lens, the lowest point of said objective lens being lower than the highest position of light which is emitted from said light source and which is incident on said first grating element in the height direction from said objective lens toward the optical recording medium of the optical head; and a photo-detector for detecting light reflected by the optical recording medium and deflected again by said light path alteration member, wherein light deflected by said light path alteration member is used as incident light on said first grating element-or said objective lens on the outgoing light path, and is used as incident light on said photo-detector or said second grating element on the return light path.