| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device capable of properly recording and reproducing a signal on each of two kinds of optical disks which are different in thickness of their substrates and recording density by setting light spots converged on the two kinds of disks to a prescribed ratio in diameter. SOLUTION: A laser beam emitted from a light emitting element 1 is converged via a collimator lens 3 and a beam splitter element 4 by an objective lens 8 onto the disk 9. A limiting aperture 5 is provided in an optical path form the light emitting element 1 to the objective lens 8 to be able to taken in and out to the optical path, and is changed depending on the kind of disk 9 so that the ratio of the light spot diameters on the disk is set to be 1:1.3 to 1:1.6. |
