A measurement illumination optical unit guides illumination light into an object field of a projection exposure apparatus for EUV lithography. The illumination optical unit has a field facet mirror with a plurality of field facets and a pupil facet mirror with a plurality of pupil facets. The latter serve for overlaid imaging in the object field of field facet images of the field facets. A field facet imaging channel of the illumination light is guided via any one field facet and any one pupil facet. A field stop specifies a field boundary of an illumination field in the object plane. The illumination field has a greater extent along one field dimension than any one of the field facet images. At least some of the field facets include tilt actuators which help guide the illumination light into the illumination field via various field facets and one and the same pupil facet.