Lithography system comprising a measurement device

Abstract

A lithography system, such as an EUV lithography system, comprises: a radiation source for generating used radiation; an optical element, such as a reflective optical element, having a surface provided for irradiation with the used radiation; and a measuring device for measuring a heat input, such as a temperature, at the surface of the optical element. The measuring device comprises a detection device for detecting radiation emanating from the surface of the optical element. The measuring device also comprises a lock-in amplifier. The lithography system comprises a heating device having at least one heating unit for irradiating the surface of the optical element with heating radiation. The heating device is designed for modulation, such as clocked modulation, for example pulsed modulation, of the heating radiation from the heating unit with which the surface of the optical element is irradiated.

Dependencies are inferred from the claim text.