| 摘要 |
An optical pickup capable of selectively emitting blue light based and red light based laser beams is moved to a radial direction of an optical disk while emitting either of the laser beams, and it is detected whether or not a track pitch of the optical disk has changed based on a signal obtained from the optical pickup. In the case where a change in the track pitch of the optical disk has been detected, the blue light based laser beam is emitted from the optical pickup. In the case where a change in the track pitch of the optical disk is not detected, the red light based laser beam is emitted from the optical pickup.
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