| 摘要 |
PURPOSE:To improve the sensitivity of inspection by comparing the difference between reflected or scattered light beams generated at a 1st time and a 2nd time with a specific threshold value. CONSTITUTION:A specific area on a body 2 to be inspected is irradiated with inspection light 3 from a light source 4 and then the surface of the body 3 to be inspected is scanned continuously by the inspection light 3. At this time, scattered or reflected light 7 generated in the specific area of the surface of the objective body 2 irradiated with the inspection light 3 is made incident on an photoelectric transducing means 6 through an objective 5. Here, the signal S1 of the quantity of light 7 detected by the means 6 at the 1st time is transmitted to a comparison part 10 through a 1st signal line 8 where a delay part D is interposed. Further, the signal S2 of the quantity of light 7 detected by the means 6 at the 2nd time which is a specific time after the 1st time is transmitted directly to a comparison part 10 through a 2nd signal line 9 and the comparison part 10 inputs the signals S1 and S2 of the quantities of light 7 at the same time and the difference in the quantity of light is compared with the specific threshold value. Thus, the sensitivity of the inspection can be improved.
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