Abstract:
A method of aligning an object may include obtaining a first actual image of a first pattern on the object, setting the first actual image as a first reference image, obtaining a second actual image of a second pattern on the object, comparing the second actual image with the first reference image to obtain first relative position difference values of the second actual image with respect to the first reference image, and converting the first relative position difference values into first absolute position difference values with respect to a reference point on the object.