A lithographic apparatus and method in which an illumination system supplies a projection beam, a patterning system imparts to the beam a pattern in its cross section, and a projection system projects the patterned beam onto a target portion of a substrate. The projection system comprises an array of...http://www.google.com.au/patents/US7158208?utm_source=gb-gplus-sharePatent US7158208 - Lithographic apparatus and device manufacturing method
