Abstract: There is provided an optical module for microlithography. The optical module includes an optical element and a retaining device for holding the optical element. The optical element has (a) a main extension plane, in which it defines a radial direction R and a circumferential direction U, and (b) a free optical diameter and an overrun in the region of its outer periphery. The retaining device contacts the optical element in the region of the overrun, and is formed and/or contacts the optical element in such a manner that the overrun ratio, calculated from the overrun related to a minimum overrun necessary for the production of the optical element, is at most 1.5.

Abstract: A mirror with a mirror carrier, as well as related apparatuses, systems and methods are disclosed. The mirror carrier can be embodied as cooling device with at least one cooling channel. Tube connections can be provided to connecting the at least one cooling channel to an inlet and an outlet of coolant. Sealing elements for a gas-tight and liquid-tight seals can be arranged between the tube connections and the mirror carrier. The field of application of the mirror can be, for example, an illumination device of a projection exposure apparatus.