PURPOSE: To detect a surface defect precisely by automatically detecting a reference value in each substance to be inspected, adding plural levels to the reference value to detect a defect and setting a threshold level.
CONSTITUTION: The positively reflected laser light irradiated from an irradiation part 13 and reflected by a substance 8 to be inspected is discharged to the external through a through-hole 31 and the dispersed and reflected laser light is detected by a photoelectric converter 29. The output of the converter 29 is supplied to a peak detector 33 and a mean value calculating part 34 through an A/D converter 32. The calculation part 34 stores a detecting signal synchronously with a sampling signal and finds out the arithmetic mean value of the obtained all data. The mean value is stored in a memory part 41, and then added to a level previously set up in the memory part 41 in accordance with the size of a surface defect to calculate its threshold level. The defect is detected on the basis of the threshold level.
YAMAJI HIROSHI
MIYOSHI MOTOSUKE
OKUMURA KATSUYA
| JPS57161642A | 1982-10-05 | |||
| JPS5744838A | 1982-03-13 | |||
| JPS5614144A | 1981-02-10 |
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