the present invention relates to a method to determine a position of at least one mark provided on a substrate , comprising the actions of : detecting a first mark on said substrate by using a first detector , detecting a first set of marks comprising at least a second mark on said substrate by using a second detector , computing a first list of relative distance between said first mark and mark in said first set of marks , detecting the second mark on said substrate by using one of said first or said second detectors , detecting a second set of marks comprising at least said first mark on said substrate by using an available detector , computing a second list of relative distance between said second mark and mark in said second set of marks , determining the position of at least one mark by using the information in said first and said second lists of relative distance .