Abstract: An optical system, for example in a microlithographic projection exposure apparatus, comprises a mirror and a temperature-regulating device. The mirror has an optical effective surface and a mirror substrate. A plurality of temperature-regulating zones are arranged in the mirror substrate. The temperature-regulating device is used to adjust the temperatures present in each of the temperature-regulating zones independently of one another. The temperature-regulating zones are arranged in at least two planes at different distances from the optical effective surface. The temperature-regulating zones in the at least two planes are configured as cooling channels through which, independently of one another, a cooling fluid at a variably adjustable cooling fluid temperature is able to flow. A method for operating such an optical system is provided.

Abstract: A method of operating a projection exposure apparatus for microlithography, comprises: heating an optical element of the projection exposure apparatus by irradiating a surface of the optical element with heating radiation during a break in operation in which the surface of the optical element is not irradiated by exposure radiation. An inhomogeneous temperature distribution which reduces aberrations of the projection exposure apparatus is created on a portion of the surface of the optical element during the heating in the break in operation, with the inhomogeneous temperature distribution being created by irradiating the portion with heating radiation with at least one continuous heating radiation profile formed by a beam shaping element. A related projection exposure apparatus for microlithography is disclosed.

Abstract: An optical system, for example in a microlithographic projection exposure apparatus, comprises a mirror and a temperature-regulating device. The mirror has an optical effective surface and a mirror substrate. A plurality of temperature-regulating zones are arranged in the mirror substrate. The temperature-regulating device is used to adjust the temperatures present in each of the temperature-regulating zones independently of one another. The temperature-regulating zones are arranged in at least two planes at different distances from the optical effective surface. The temperature-regulating zones in the at least two planes are configured as cooling channels through which, independently of one another, a cooling fluid at a variably adjustable cooling fluid temperature is able to flow. A method for operating such an optical system is provided.