Patent ID: 9201312
Filing Date: 2015-12-01
Classification: G03F,G06K,G06T

Abstract:
1. A method for correcting optical errors occurring in coordinates of positions of targets measured via an imaging system, the method comprising the following steps: a) placing an array of targets in a field of view of the imaging system, wherein a plurality of targets of the array of targets are within the field of view of the imaging system and wherein the relative positions of targets within the array of targets are fixed; b) measuring the coordinates of the plurality of targets of the array of targets repeatedly via the imaging system, wherein the array of targets is shifted relative to the field of view of the imaging system between the repeated measurements; c) determining an alignment function from the measurement results of step b, the alignment function being a function of coordinates of the field of view of the imaging system and giving an additive correction for optical errors of the coordinates of positions of targets measured by the imaging system; d) correcting the coordinates of the positions of the targets measured by the imaging system by adding the respective value of the alignment function at the field-of-view coordinates at which the coordinates of the position of the respective target were measured; and, e) obtaining a final result for the position of each target of the plurality of targets by averaging over the corrected coordinates found in step d for the respective target at each relative position of the targets and field of view of the imaging system.