Abstract: In each configuration, at least one TDI sensor is used to image the portions of interest of the substrate that are substantially uniformly or critically illuminated. In one configuration, the substrate is compared to the expected characteristic features prestored in memory. In a second configuration, a first and second pattern in a region of at least one substrate are inspected by comparing one pattern against the other and noting whether they agree with each other. This is accomplished by illuminating the two patterns, imaging the first pattern and storing its characteristics in a temporary memory, then imaging the second pattern and comparing it to the stored characteristics from the temporary memory. Then the comparisons continue sequentially with the second pattern becoming the first pattern in the next imaging/comparison sequence against a new second pattern. With each comparison whether there has been agreement between the two patterns is noted.