An optical module, in particular for microlithography, with an optical element unit, a support device, a deformation device and a measuring device is disclosed. The support device is supported on the optical element unit, whereas for deforming an optical surface of the optical element unit, the deformation device engages a deformation section of the optical element unit comprising the optical surface. For determining the position and/or the orientation of the optical element unit with respect to an external reference in at least one degree of freedom, the measuring device comprises at least one measuring element, wherein the measuring element is arranged on a reference section of the optical element unit.