In the defect inspection method using patterned area illumination, a defect upon an industrial product is detected from an image emphasized by the patterned area illumination. All defects detected by the inspection method, however, is not unsuitable as a finished product. Therefore, GOOD/NG judgment which judges that the defect is good or no-good as a finished product is required frequently. Shape estimation of a defect is useful for the GOOD/NG judgment. This study proposes a method of the shape estimation. An image obtained by this inspection method is influenced by size of a pattern on the illumination, because the pattern on the image is reflected image/shadow at slope of the defect that is equal to the shape of the defect. Hence, a difference image between two images obtained by two different patterns has information of the slope. We developed the method to estimate the shape of the defect by the difference image. The utility of the method of shape estimation was confirmed through the simulation and the experiment.
shape estimation
patterned area illumination
circle pattern
difference image