An optical system of a microlithographic projection exposure apparatus comprises at least one mirror arrangement, having a plurality of mirror elements which are adjustable independently of one another for varying an angular distribution of the light reflected by the mirror arrangement, a polarization-influencing optical arrangement, by which, for a light beam passing through during the operation of the projection exposure apparatus, different polarization states can be set via the light beam cross section, and a retarder arrangement, which is arranged upstream of the polarization-influencing optical arrangement in the light propagation direction and at least partly compensates for a disturbance of the polarization distribution that is present elsewhere in the projection exposure apparatus, wherein the polarization-influencing optical arrangement has optical components which are adjustable in their relative position with respect to one another, wherein different output polarization distributions can be produced by this adjustment in conjunction with the mirror arrangement.