Illumination optical unit for projection lithography

An illumination optical unit (32) for projection lithography serves for illuminating an object field (5), in which an object to be imaged can be arranged, with illumination light (14). The illumination optical unit has a collector for collecting the emission of a light source for the illumination light (14). The collector is arranged such that it transfers the illumination light (14) from the light source into an intermediate focus (16). The illumination optical unit (32) furthermore has a field facet mirror (20) and a pupil facet mirror (21), each having a plurality of facets (22, 23). The field facets (22) are imaged into the object field (5) by a transfer optical unit (21). The illumination optical unit (32) additionally has an individual-mirror array (17) having individual mirrors tiltable in a manner driven individually, said array being arranged upstream of the field facet mirror (20) and downstream of the intermediate focus (16) in an illumination beam path (26). The intermediate focus (16) is imaged via illumination channels (24), which are each formed by at least one of the individual mirrors and at least one of the field facets (22) and which guide a partial beam of the illumination light (14), into a spatial region (25) in which the pupil facet mirror (21) is situated. This results in illumination of the object to be imaged which can be designed in a flexible fashion and is readily adaptable to predetermined values.