| 摘要 |
PURPOSE:To perform simply and securely the defect inspection of a rough inspection surface by using a lens for an irradiating device and putting an apparent position closer to the inspection surface. CONSTITUTION:The lens 10 is fitted to the aperture end part of the irradiating device 3 and the side of the lens 10 is placed opposite the inspection surface 2. Light from a light source 7 is guided to the lens 10 through a scattering plate 5 and a grating 9. The lens 10 forms a grating image 1 of the grating 9 on the side in the heading direction of the light. Therefore, the apparent position of the grating image 1 is put closer to the inspection surface 2 and the distance l from the inspection surface 2 to the grating image 1 decreases. Consequently, the distance l between the mirror image 1'' of the grating image 1 and inspection surface 2 also decreases and variation of the mirror image also decreases correspondingly. Therefore, unevenness based upon the surface defect in the inspection surface 2 is larger than that based upon the roughness of the inspection surface 2, so only the unevenness based upon the surface defect is captured as variation of the sharp mirror image 1'', so that the surface defect is inspected very easily and securely. |
