A zoom system that is particularly suited to use on an illumination device of
a
microlithographic projection exposure system and is configured in the form of a
focal-length-zooming lens. The lenses of the zoom system define an object plane
(6) and an image plane (8) that is a Fourier transform of the object
plane. Both an intermediate pupillary plane (25) that is conjugate to the
image plane and an intermediate field plane (27) that is a Fourier transform
of the image plane lie between the object plane (6) and image plane (8).
At least one movable lens (31, 32) is arranged in the vicinity of these
intermediate image planes (25, 27). The system is characterized by a large
expansion of the illuminated area on the image plane for short lengths of travel
and light weights of these movable lenses (31, 32).
