| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a detection method of a tracking error signal in which reduction in tracking error signal is made small even though the range of an objective lens shift becomes large and no phase shift occurs with respect to the periodic structure of the recording surface of an optical disk during DVD-RAM recording. <P>SOLUTION: The tracking error signal is detected by using a diffraction grating 12 having a structure in which a diffraction grating 12a and a diffraction grating 12b having the same cycle of the diffraction grating 12a are joined together with a 180 degree phase shift to form a region 38 where the diffraction gratings 12a and 12b are engaged with each other along the grating groove direction with a prescribed width and diffraction separating the laser beams emitted from a light emitting element by the diffraction grating 12 and utilizing 0-order and ±1st diffracted light beams. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
