| 摘要 |
The present invention is characterized by the following: incident illumination and oblique illumination are performed on a scratch and a foreign material, which have been made on a surface of a polished or a ground insulating layer, with substantially the same luminous flux; and on the basis of a correlation such as a ratio of intensity of scattered light generated by the shallow scratch and the foreign material between the incident illumination and the oblique illumination, the shallow scratch is discriminated from the foreign material.
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