Patent ID: 6285440
Filing Date: 2001-09-04
Classification: G03F

Abstract:
An illumination system for illuminating an illumination region having a difference in size along a first direction and a second direction perpendicular to the first direction, said illumination system comprising:an optical integrator including elements having different refractive powers with respect to the first and second directions as the optical integrator is viewed in an optical axis direction, said elements also having the same pitch with respect to the first and second directions; andoptical means for directing light from a light source upon said optical integrator, at different largest incidence angles with respect to the first and second directions, so as to satisfy a relation0.8<[(tan .theta..sub.1 /tan .theta..sub.2)/(.phi..sub.1 /.phi..sub.2)]<2.1where .theta..sub.1 and .theta..sub.2 are largest incidence angles of the light incident on said optical integrator with respect to the first and second directions, and .phi..sub.1 and .phi..sub.2 are refractive powers of said optical integrator with respect to the first and second directions.