| 摘要 |
PROBLEM TO BE SOLVED: To reproduce optical disks having different recording densities. SOLUTION: A first optical part 21 generates a laser beam and converges it with a prescribed numerical aperture corresponding to an optical disk 11a whose data recording density is low. A second optical part 22 converts the converged light from the first optical part 21 into the converged light having a prescribe numerical aperture corresponding to an optical disk 11b whose data recording density is high. When the optical disk 11 to be reproduced is the optical disk 11a, since the second optical part 22 is retreated from between the first optical part 21 and the optical disk 11a, the optical disk 11a is directly irradiated with the laser beam from the first optical part 21 and when the optical disk 11 is the optical disk 11b, since the second optical part 22 is inserted in between the first optical part 21 and the optical disk 11b, the optical disk 11b is irradiated with the laser beam from the second optical part 22. |
