| 摘要 |
PURPOSE:To detect a chucking state of a disk. CONSTITUTION:The laser beam from a laser light emitting element 1 is focused on a disk 7 by means of an objective lens 5 through a beam splitter 4. The reproduction light beam is reproduced by a first photodetector 9 through the objective lens 5 and the beam splitter 4. A second photodetector 6 is placed around the disk 7 of the objective lens 5. With the second photodetector 6, the diffracted rays by the disk 7 is received. Based on the light receiving output, the chucking state of the disk 7 is detected. |
