A projection exposure apparatus for microlithography using a wavelength≦193 nm, includes (A) a primary light source, (B) an illumination system having (1) an image plane, (2) a plurality of raster elements for receiving light from the primary light source, and (3) a field mirror for receiving the light from the plurality of raster elements and for forming an arc-shaped field having a plurality of field points in the image plane, and (C) a projection objective. The illumination system has a principle ray associated with each of the plurality of field points thus defining a plurality of principle rays. The plurality of principle rays run divergently into the projection objective.