| 摘要 |
<p>PURPOSE:To detect an edge pattern with facility by using a lighting step of a compact type and a good operating performance in such a manner that a ring-like light passage onto the edge pattern is partly shaded and light is radiated from the top onto a dark site, and the reflecting light is detected. CONSTITUTION:A light emitted from a lamp 7 toward a rectilinear stepped pattern such as a circuit pattern 4 of an integrated circuit wafer, etc., is collected by a collector lens 8, only top and bottom portions 14 are allowed to pass by a light-shading slit 13 formed by being combined with a ring-like slit, the light is radiated though a ring-like mirror 10 and a ring-like condenser lens 11, and only an edge (solid line) 16 in the same direction as an arrow 15 is detected by irregular reflection using an object lens 12. And then, an edge 17 directed perpendicularly to the other edge is detected either by turning the light-shading slit 13 by 90 deg. or by replacing it with a slit in different direction. This irregular reflecting light is passed through the object lens 12 and formed into an image on a light-receiving surface of a image-projecting device and a position of the edge pattern is detected by characteristic point of the signal.</p> |
