An illumination optical unit for projection lithography illuminates an object field with illumination light. The illumination optical unit has a collector for collecting the emission of a light source for the illumination light. The collector is arranged such that it transfers the illumination light from the light source into an intermediate focus. The illumination optical unit furthermore has a field facet mirror and a pupil facet mirror, each having a plurality of facets. The field facets are imaged into the object field by a transfer optical unit. The illumination optical unit additionally has an individual-mirror array having individual mirrors tiltable in a manner driven individually. The array is arranged upstream of the field facet mirror and downstream of the intermediate focus in an illumination beam path.