The invention relates to an optical system of a microlithographic projection exposure apparatus, comprising a mirror arrangement having a plurality of mirror elements which are adjustable independently of one another for the purpose of changing an angular distribution of the light reflected by the mirror arrangement, a polarization-influencing optical arrangement having at least one polarization-influencing component, wherein, by displacing the polarization-influencing component, a degree of overlap between the polarization-influencing component and the mirror arrangement can be set in a variable manner, and a deflection device having a respective reflection surface upstream and downstream of the mirror arrangement relative to the light propagation direction.