| 摘要 |
PROBLEM TO BE SOLVED: To easily discover a surface defect, and to reduce the fatigue of an inspector by radiating a plurality of beams of different dominant wavelength in a duplicate manner on the surface of a work to be inspected, and visually judge the surface defect. SOLUTION: A short wavelength light source 1 having a dominant wavelength on the short wavelength side and a long wavelength light source 2 having a dominant wavelength on the long wavelength side are provided on the same side as a work 3 to be inspected. The beam from the short wavelength light source 1 is arranged to be duplicated with the beam from the long wavelength light source 2 on the surface of the work 3. Since a plurality of beams of different dominant wavelength are radiated so as to be duplicated on the surface of the work 3, and a surface defect is visually judged, the surface defect is less overlooked. Both the surface defect easy to detect by the short wavelength beam having the dominant wavelength on the short wavelength side and the surface defect easy to detect by the long wavelength beam having the dominant wavelength on the long wavelength side are very easy to detect. This means that the beams of the wavelength suitable for the surface defect to be inspected are projected in a duplicate manner on a part to be visually inspected.
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