| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device for carrying out stable tracking error difference detection for a plurality of optical information recording media having guide groove pitches different from one another while holding advantages of an in-line type DPP system. <P>SOLUTION: This device is provided with a diffraction grating 12 for branching an optical beam emitted from a semiconductor laser element into at least three optical beams. The diffraction grating 12 is divided into three areas by straight lines extending in a direction parallel to the track tangential line of an optical information recording medium, and a second area 12B is divided into first and second sub-blocks 13 and 14 by a straight line extending in parallel with the radial direction of the optical information recording medium. Phases of the first and second sub-blocks 13 and 14 are different by about 180°. The phase of the first area 12A is different from that of the first sub-block 13 by about 90°, and phases of the first and third areas 12A and 12C are different by about 180°. <P>COPYRIGHT: (C)2008,JPO&INPIT |
