Patent ID: 6816247
Filing Date: 2004-11-09
Classification: G01M,G03F

Abstract:
A moirÃ© method for measuring the distortion of an optical imaging system comprising:arranging an object grating having a two-dimensional object pattern in an object plane of the imaging system; arranging an image grating having a two-dimensional image pattern in an image plane of the imaging system; wherein the object pattern and the image pattern are adapted to suit one another such that a two-dimensional moirÃ© fringe pattern is created when the object pattern is imaged onto the image pattern by the imaging system; imaging the object pattern onto the image pattern in order to create a two-dimensional moirÃ© fringe pattern; detecting the moirÃ© fringe pattern; and determining at least one first distortion component and at least one second distortion component from the two-dimensional moirÃ© fringe pattern, wherein the first distortion component is correlated to a first image direction of an image plane and the second distortion component is correlated to a second image direction of that image plane that is transverse to the first image direction.