| 摘要 |
PURPOSE:To detect a defect without being affected by the inclination of a pattern to be inspected by detecting variation in tilt angle at each edge position of the pattern to be inspected. CONSTITUTION:An input image signal 2 which is read out by a photoelectric converting scanner 1 is converted 3 into a binary image signal, which is raster- scanned to detect positions where 0 changes into 1 and 1 changes into 0 by an edge detector 5, thereby sending out an edge image signal 6. Then the signal 6 is traced in order and the inclination of the pattern to the horizontal direction is calculated 7 from edge position coordinates between two points which are at a constant distance; and an inclination signal 8 of each edge position is outputted and the maximum value thetaM and the edge positions SM where the maximum value is obtained and the minimum value thetaN and the edge position SN where the minimum value is obtained are detected 9 to output extremum signals 10. Further, when the distance between the positions SM and SN is smaller than a definite value SST, and the difference between the maximum value thetaM and minimum value thetaN is larger than a definite value thetaST, a defect decision circuit 11 decides a defect and outputs a decision signal. |
