| 摘要 |
PROBLEM TO BE SOLVED: To perform an in-line 100% inspection in each process which contains a defect inspection in a single clear disk state immediately after a molding operation in an optical-disk reproduction process. SOLUTION: Light from a light source 220 is condensed by a condensing lens 222. The condensed light is passed through a pinhole 224, and parallel light is generated through a high-performance large collimating lens 226 whose visual field is a disk radius. The optical path of the parallel light is changed by 90 deg. in a beam splitter 214, and the disk surface of an optical disk 230 to be inspected is irradiated with the parallel light. Reflected light from the disk 230 passes a lens system 212 so as to be incident on a camera 210. The radiated parallel light is changed into a diffused light even for a fine defect in a height of 10 nm or higher and in a size of about 25μm, the gray level of the light receiving image of the defect is changed in a good S/N ratio, and the fine defect of the optical disk can be detected.
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