| 摘要 |
PURPOSE:To enable easy detection of even a bitten defect with a small angle of inclination and a gently swelling defect, by making a reflected light from the surface of an object to be measured incident upon a light receiving position detecting means to detect a dislocation of the light receiving position due to a surface defect. CONSTITUTION:The reflected light (R) of a laser light (L) directed to the surface 5 of an object to be inspected is turned by 90 deg. in the direction of deflection with a 1/4 wavelength plate 3 and reflected with a beam splitter 2 to be received on a light receiving surface 7 of a bright point position detector 6. When a bitten defect 21 exists on the surface 5, the laser light is reflected by an angle of deflection of 2theta and hence dislocated by DELTAX from a reference position X0 on the surface 7. A comparator 10 compares this dislocation with a reference value and outputs a defect signal. This enables easy detection of a bitten defect with a small angle of inclination and a gentle swelling defect.
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