Projection exposure apparatus for semiconductor lithography

The invention relates to a projection exposure apparatus (1) for semiconductor lithography having a projection optical unit (9) comprising a sensor frame (30), a carrying frame (40), having a module (50) having an optical element (52) and actuators (53) for positioning and orienting the optical element (52), wherein the module (50) is arranged on the carrying frame (40) and the sensor frame (30) is embodied as a reference for the positioning of the optical element (52), and wherein the module (50) comprises an infrastructure (60). According to the invention, the infrastructure (60) is embodied such that it comprises interfaces (62, 70) for separating a module (50) from the projection optical unit (9). Furthermore, the invention comprises a method for exchanging a module (50) of a projection optical unit (9) of a projection exposure apparatus (1) for semiconductor lithography, wherein the module (50) comprises an optical element (52). According to the invention, the reference (55) for positioning and/or orient