| 摘要 |
PURPOSE:To detect only a defect regardless of the condition such as the denseness degree or shape of an original pattern. CONSTITUTION:A shading plate 26 having an aperture 25 formed thereto is arranged in the vicinity of the Fourier transform surface to an object 19 to be inspected of a light receiving lens 24 and the light passing through the aperture 25 is condensed (formed into an image) to the light detection surface of a photodetector 33 by a lens 32. The shading plate 26 is rotated by a drive part 28 to change the relative position of the Fourier transform pattern of the light from the object 19 to be inspected, with the aperture 25 and a defect is detected at a place where the photoelectric conversion signal of the photodetector 33 becomes min. |
