US Patent 7477365 Optical spot geometric parameter determination using calibration targets

A method, system and computer program product for determining a geometric parameter of an optical spot of a light beam are disclosed. A method comprises: providing a calibration target, the calibration target including a systematic variation in a parameter; measuring the calibration target with respect to the systematic variation using the light beam to obtain a plurality of measurements; and analyzing the measurements and the systematic variation to determine the geometric parameter of the optical spot.