Imaging optics and projection exposure system for microlithography with such imaging optics

An imaging optical system (7) has a plurality of mirrors (M1 to M6) which image an object field (4) in an object plane (5) into an image field (8) in an image plane (9). The imaging optics (7) has a pupil obscuration. The last mirror (M6) in the optical path of imaging light (3) between the object field (4) and the image field (8) has a passage opening (18) for the passage of imaging light (3). A in the beam path of the imaging light (3) between the object field (4) and the image field (8) the penultimate mirror (M5) of the imaging optics (7) has no through hole for the passage of imaging light (3). The result is an imaging optical system, with a manageable combination of low aberrations, and good controllable production throughput for the image-light is reached.