Patent ID: 7288779

Claim:
A method of position determination, said method comprising: obtaining a first set of signals, each signal of the first set corresponding to a respective one of a plurality of portions of light received by a detector, wherein the first set is generated by detection of a first beam of light affected by an alignment feature of a substrate; obtaining one or more additional sets of signals such that each signal in the one or more additional sets corresponds to a respective one of the plurality of portions and each set is generated by detection of a respective one or more additional beams of light affected by the alignment feature of the substrate; for each portion of light, determining a variance between a corresponding one of the signals in the first set and a corresponding one or more of the signals in the one or more additional sets; selecting at least one from among the plurality of portions based on a result of said determining a variance; and supplying or making available signals corresponding to the at least one from among the plurality of portions which was selected, for further analysis and processing to determine a position.