| 摘要 |
PROBLEM TO BE SOLVED: To decide the quality of an optical disk by detecting the height of a defect generated on the protection surface of the optical disk. SOLUTION: The surface of an optical disk 9 is irradiated with laser light from a laser light source 1 through right-angled prisms 5, 6, and 8. Its reflected light is photodetected by PSD(position sensitive device) 10. If there is any defect on the surface of the optical disk 9, the photodetection position of the PSD 10 varies with the detect. Since the peak value of the variation of the photodetection position correlates with the height of the defect, the height of the defect is detected according to the variation of the photodetection position. Furthermore, the quality of the optical disk can be detected according to the height of the defect.
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