A catadioptric projection objective which images a pattern arranged in an
object plane of the projection objective into the image plane of the
projection objective while generating a real intermediate image has a
catadioptric objective part having at least one concave mirror and a beam
deflecting device and also a dioptric objective part. The imaging system
has a system diaphragm having a variable diaphragm diameter for variably
limiting the cross section of the radiation passing through the
projection objective. This system diaphragm is arranged in the
catadioptric objective part, preferably in direct proximity to the
concave mirror. The invention enables a projection objective with a
simple construction.