An optical module includes: a first holding device with a circumference extending in a first circumferential direction; and a plurality of first supporting devices configured to support a first optical element, the first supporting devices being fixed at the circumference of the first holding device. Along the first circumferential direction, at least one of the first supporting devices is located in a non-equidistant manner between two neighboring first supporting devices. The optical module is configured to be used in a microlithography objective.

An imaging optical unit for imaging an object field in an image field is disclosed. The imaging optical unit has an obscured pupil. This pupil has a center, through which a chief ray of a central field point passes. The imaging optical unit furthermore has a plurality of imaging optical components. A gravity center of a contiguous pupil obscuration region of the imaging optical unit lies decentrally in the pupil of the imaging optical unit.

An EUV mirror with a substrate and a multilayer arrangement including: a periodic first layer group having N1>1 first layer pairs of period thickness P1 and arranged on a radiation entrance side of the multilayer arrangement; a periodic second layer group having N2>1 second layer pairs of period thickness P2 and arranged between the first layer group and the substrate; and a third layer group having N3 third layer pairs arranged between the first and second layer groups. N1>N2. The third layer group has a third period thickness P3 which deviates from an average period thickness P.sub.M=(P1+P2)/2 by a period thickness difference P. P corresponds to the quotient of the optical layer thickness (/4) of a quarter-wave layer and the product of N3 and cos(AOI.sub.M), AOI.sub.M being the mean incidence angle for which the multilayer arrangement is designed.