| 摘要 |
PROBLEM TO BE SOLVED: To measure displacement of an optical disk highly accurately with an extremely simple constitution, and to execute recording and reproduction processing, while controlling a focus to the displacement of the optical disk. SOLUTION: Laser light is irradiated from the side toward a circumferential side part of the mounted optical disk 2, and return light from the circumferential side part irradiated with the laser light is received, and the displacement of the optical disk 2 is measured based on the quantity of the received return light. Focus adjustment to an information recording face is executed according to the measured displacement of the optical disk. COPYRIGHT: (C)2005,JPO&NCIPI
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