| 摘要 |
<p>PURPOSE:To detect the defects accurately over a wide range wherein the slant degree is gently changed in a waviness pattern by providing a slant detecting means and a slant-change detecting means. CONSTITUTION:The surface of a body 1 to be detected is scanned with a laser beam as a spot light. The reflected light is received by a light receiving part 12. Then, a slant detecting means 20 receives the position signal from the light receiving part 12. The signal is compared with a reference level. The number of large pulses on the positive and negative sides of the position signal is counted, and the result is outputted to an inspecting means 22. A slant-change detecting means 21 receives the position signal from the light receiving part 12 and performs time differentiation. Thus, the changing degree of the slant of the illuminated position of the body to be detected 1 is obtained. Then, the signal is compared with the reference level, and the number of the large pulses on the positive and negative sides is counted, and the result is outputted into the inspecting means 22. The judging means 22 detects the defect based on the output signals of the means 20 and 21.</p> |
