| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk drive which suitably records and/or reproduces information even to/from optical disks where a first recording layer and a second recording layer are respectively covered with translucent layers of different thicknesses. <P>SOLUTION: The optical disk drive 1 records and/or reproduces the information in the DVD-based and CD-based optical disks 11 and 12, and records and/or reproduces information to/from an optical disk of a single-sided double-layer DVD-ROM standard where the first recording layer 111 and the second recording layer 112 are respectively covered with a first translucent layer 116 and a second translucent layer 117 of different thicknesses as the optical disk 11. When a fifth-order spherical aberration of an objective lens 45 in the case of recording and/or reproducing to/from the optical disk 11 with laser beam L1 of a wave length λ<SB>1</SB>is denoted by SA5, λ<SB>1</SB>and SA5 are set to meet the following formula -0.025λ<SB>1</SB>rms≤SA5≤+0.025λ<SB>1</SB>rms. <P>COPYRIGHT: (C)2007,JPO&INPIT |
