| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a reduction in quality of a tracking error signal STE even when an objective lens does not exist on a radius of an optical disc. <P>SOLUTION: A sub-beam SB is separated from a light beam so that, in a reflected light spot QB formed when the sub-beam SB reflected on a signal recording layer of the optical disc is received by a light receiving device 8, a light amount of an overlapping region W in which a primary light region AR0 of a zeroth-order light beam formed by the sub-beam SB diffracted on the optical disc, and ±first-order light beams, is smaller than that of a central region ARc which is a region other than the overlapping region W of the primary light region AR0. <P>COPYRIGHT: (C)2008,JPO&INPIT |
