摘要 |
PROBLEM TO BE SOLVED: To provide a disk inspecting method which enables precise measurement of the film thickness of a pigment layer formed on a CD-R disk. SOLUTION: The CD-R disk 14 is irradiated with a laser beam 8, and the transmitted laser beam 8 is converted into an electrical signal by a photodetector 10. Subsequently, the film thickness of the pigment layer is calculated from the electrical signal, based on a relational expression which shows the relation between the electrical signal and the film thickness of the pigment layer, and the quantity as to whether the CD-R disk 14 is nondefective is determined. Thus, until the inspection of the CD-R disk 14 to be subsequently inspected is started, after the completion of the inspection of the CD-R disk 14, the photodetector 10 is directly irradiated with the laser beam 8, and the relational expression is calibrated in accordance with the electrical signal thus gained.
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