A lithography system includes an illumination source, projection optical elements, and a pattern mask. The illumination source includes one or more illumination poles. The pattern mask includes a set of focus-sensitive mask elements distributed with a pitch and, is configured to diffract illumination from the one or more illumination poles. The pitch may be selected such that two diffraction orders of illumination associated with each of the one or more illumination poles are asymmetrically distributed in a pupil plane of the projection optical elements. Further, the projection optical elements may expose a sample with an image of the set of focus-sensitive pattern mask elements based on the two diffraction orders of illumination associated with each of the one or more illumination poles such that one or more printing characteristics is indicative of a position of the sample within a focal volume of the projection optical elements.