Illumination optical system for microlithography for guiding illumination light from a primary light source to an object field, - with a mirror array with a plurality of individual mirrors, which can be tilted independently of one another by actuators and are connected to associated tilting actuators, - with a controller for activating the actuators, - with a raster module with a plurality of raster elements (28, 30) for producing a spatially distributed arrangement of secondary light sources, - wherein the raster module is arranged in the region of a plane of the illumination optical system, in which an emergent angle (AR x, AR y), at which an illumination light part bundle leaves one of the raster elements (28, 30), is precisely allocated to a location region in the object field, on which the illumination light part bundle impinges on the object field, - wherein the controller is configured in such a way that a specification of a tilting angle for each individual mirror is allocated to a predetermined field-dependent desired course of illumination angle intensity distributions (I 1 (x), I 2 (x), I 3 (x), I 4 (x)), by which object field points distributed over the object field are impinged upon, - wherein the raster module has two raster arrangements (18, 21), which are arranged one behind another in the beam path of the illumination light, each with a plurality of raster elements (28, 30), - characterized in that the arrangement and configuration of the two raster arrangements (18, 21) is such that a diameter of the illumination light part bundle, which impinges on one of the raster elements of the second raster arrangement, is smaller than one half of a total entry or impingement face of the raster element of the second raster arrangement. - with a mirror array with a plurality of individual mirrors, which can be tilted independently of one another by actuators and are connected to associated tilting actuators, - with a controller for activating the actuators, - with a raster module with a plurality of raster elements (28, 30) for producing a spatially distributed arrangement of secondary light sources, - wherein the raster module is arranged in the region of a plane of the illumination optical system, in which an emergent angle (AR x, AR y), at which an illumination light part bundle leaves one of the raster elements (28, 30), is precisely allocated to a location region in the object field, on which the illumination light part bundle impinges on the object field, - wherein the controller is configured in such a way that a specification of a tilting angle for each individual mirror is allocated to a predetermined field-dependent desired course of illumination angle intensity distributions (I 1 (x), I 2 (x), I 3 (x), I 4 (x)), by which object field points distributed over the object field are impinged upon, - wherein the raster module has two raster arrangements (18, 21), which are arranged one behind another in the beam path of the illumination light, each with a plurality of raster elements (28, 30), - characterized in that the arrangement and configuration of the two raster arrangements (18, 21) is such that a diameter of the illumination light part bundle, which impinges on one of the raster elements of the second raster arrangement, is smaller than one half of a total entry or impingement face of the raster element of the second raster arrangement.