An illumination optical unit for projection lithography illuminates an illumination field with illumination light of a primary light source. The illumination optical unit has a raster arrangement to predefine a shape of the illumination field, a transfer optical unit for the superimposing transfer of the illumination light toward the illumination field, and an illumination angle variation device which deflects the illumination light with different deflection angles. The illumination angle variation device has at least one displaceable illumination angle variation unit to generate a deflection angle for the illumination light.