| 摘要 |
PROBLEM TO BE SOLVED: To record and reproduce information of various specific optical information recording media with only one device by providing a mechanism for changing characteristics of a light beam in a prescribed position in an optical path. SOLUTION: An objective disk is placed on a spindle motor by a user, and the kind of this disk is inputted from a host system. This input signal is sent to a diaphragm control circuit 131, so that a 2nd diaphragm part 150 is controlled to move into a prescribed position in the optical path 141 of a laser. Then, the inserting state of a shutter 151 is held. When a placed disk has no need of the 2nd diaphragm part 150, but the 2nd diaphragm part 150 has already moved in the optical path, the shutter 151 is controlled to rotate by moving a carriage 104, so that the 2nd diaphragm part 150 is ejected out. By using this device, it is not necessary to have plural object lens device sets. |
