| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup provided with a spherical aberration compensation optical system in which the quantity of the compensation of spherical aberration caused by the substrate thickness error of a disk medium can be set over two steps of large and small steps, in a optical pickup for recording and reproducing a multi-layer disk medium in which density is high, using high NA objective lens. <P>SOLUTION: Such a spherical aberration compensation system 105 is so constituted that a first compensation lens 115, a second compensation lens 116, and a third compensation lens 117 are arranged on an optical path between a laser light source 101 and an objective lens 108 along an optical axis 112 direction, and the system is provided with a drive means for displacing one or two compensation lens out of the first to the third compensation lens from the reference position into the optical axis 112 direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
