| 摘要 |
PURPOSE:To detect the fine unevenness of the entire surface of a body to be inspected easily for the inspection of the surface, by inspecting the illuminance distribution of a spatial image of reflected light from the body to be inspected by shifting the focal point of a convex lens which focuses and image-forms said reflected light. CONSTITUTION:Light from a light source 11 is collimated by a lens 23 and reflected by a body 13 to be inspected. This reflected light is condensed through a photodetection lens 24 and then projected on a photodetection surface 14, so that the same image as an image at a focus position A appears on the photodetection surface. When the body to be inspected has a completely specular surface, a completely plane specular surface image appears at the position A and there is no variation on the photodetction surface. When, however, the body to be inspected has a recessed part 25, this serves as a concave surface mirror to scatter the parallel beam, so different illuminance distribution (b) is obtained at positions A, A' and A''. Since the light is condensed gradually from the recessed part in the order of the positions A', A and A'', so waveforms shown in the figure are obtained. For this purpose, the focus positions A'-A'' are scanned successively and the image on the photodetection surface is only observed. |
