| 摘要 |
PROBLEM TO BE SOLVED: To detect a flaw regardless of the thickness or angle of a protuberance. SOLUTION: The imaging region 24 on a transparent sheer 16 by an imaging means 23 is irradiated with the light transmitted through the transparent sheet 16 from the rear surface thereof to be emitted to the visual field outer region 25 of the imaging means 23 from a plurality of directions at the same time, and the light refracted toward the visual field inner region 27 of the imaging means 23 by the flaw 20 on the transparent sheet 16 is detected by the imaging means 23.
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