| 摘要 |
PURPOSE:To make it possible to detect a flaw with high accuracy even if an article to be inspected is replaced with other one, by setting a threshold value on the basis of scattered beam data from the surface of the article to be inspected and comparing said level with the peak value of each scattered beam data. CONSTITUTION:The laser beam from a laser oscillator 28 is allowed to irradiated an article 8 to be inspected and the scattered reflected beam from the article 8 to be inspected is condensed by a diffusion surface 30 and the analogue detection signal SA having the voltage value corresponding to the receiving quantity of beam from a photoelectric converter 29 is outputted to an A/D converter 32. Subsequently, the signal SA is converted to a digital detection SB by the converter 32 to be outputted to an average calculation part 34 and a peak detection part 33. In the calculation part 34, the arithmetic average value of all data is calculated and a threshold level is set from said average value while the peak value at every definite period is calculated from the signal SB in the detection part 33. In a flaw sorting part 36, this peak value is subjected to the comparing operation with the threshold level and the surface flaw of the article to be inspected is subjected to judging processing. This data is once stored in a memory part 27. |
