Euv radiation energy sensor

Abstract

A sensor for measuring energy of EUV radiation from combined radiation including EUV radiation and non-EUV radiation, the sensor including: a radiation absorber configured to absorb radiation derived from the combined radiation via a surface of the radiation absorber; a first reflector having a first reflectivity to EUV radiation configured to modify the combined radiation entering the surface; a second reflector having a second reflectivity to EUV radiation configured to modify the combined radiation entering the surface, the second reflectivity being different from the first reflectivity; a thermometer configured to measure a temperature change of the radiation absorber; and a calculator configured to calculate the energy of EUV radiation based on a first temperature change associated with the combined radiation modified by the first reflector and a second temperature change associated with the combined radiation modified by the second reflector.

Dependencies are inferred from the claim text.