An alignment system for optical lithography uses cameras fixed to a movable stage and to a lithography unit to view unique microscopic non-uniformities that are inherent to the surface of a work piece, e.g., metal or ceramic microcrystalline grains, for position referencing. Stage cameras image two sites...http://www.google.fr/patents/US7847938?utm_source=gb-gplus-shareBrevet US7847938 - Alignment system for optical lithography
