Patent ID: 7333178

Claim:
A lithographic projection apparatus, comprising: an illumination system configured to condition a beam of radiation; a support configured to support a patterning device, the patterning device configured to pattern the beam of radiation according to a desired pattern; a substrate table configured to hold a substrate; and a projection system configured to project the patterned beam of radiation onto a target portion of the substrate, wherein the illumination system comprises a field faceted mirror comprising a plurality of field facets and configured to receive radiation from a radiation source and form a plurality of images of the radiation source on corresponding pupil facets of a pupil faceted mirror, each of the field facets being configured to provide an illumination slit at a level of the patterning device, the illumination slits being summed and superimposed together at the level of the patterning device to illuminate the patterning device; and a first blade configured to block radiation from the radiation source, the first blade being selectively actuable to cover a portion of a selectable number of field facets.