A projection exposure apparatus for transferring, by projection exposure, a pattern of a first object onto a second object while scanning the first and second objects in synchronism with each other, includes an illumination optical system having a secondary light source forming system for forming a secondary...http://www.google.com.au/patents/US6323937?utm_source=gb-gplus-sharePatent US6323937 - Projection exposure apparatus, and device manufacturing method using the same
