Patent ID: 6693713
Filing Date: 2004-02-17
Classification: G03F

Abstract:
A mark detection method comprising:irradiating a mark formed on an object with a detection beam; forming an image of said mark through an image-forming system; converting the image of said mark formed on an image pickup element into an electrical image signal in order to output a signal related to said electrical image signal at predetermined sampling intervals; performing a smoothing operation to remove a component having a cycle being equal to or less than a predetermined cycle from said signal output at said sampling intervals; and performing interpolation on said signal related to said electrical image signal in a cycle equal to or less than said predetermined sampling interval, wherein said image pickup element has a predetermined pixel size said predetermined sampling interval includes a cycle of said predetermined pixel size, said interpolation is performed in a cycle equal to or less than said predetermined pixel size, said pixel size Ps is a predetermined multiple of a minimum periodic component Pmin of an image formed on said image pickup element, and said smoothing operation removes a periodic component equal to or less than 1/(1/Psâˆ’1/Pmin), on the basis of said predetermined pixel size Ps and said minimum periodic component Pmin.