Radiation system, lithographic apparatus, device manufacturing method, and device manufactured thereby

A radiation system for multiplexing radiation includes two radiation sub-sources. The sub-sources each provide a certain amount of radiation. The system further includes a member with reflecting surfaces. The surfaces are arranged in such a way that they receive the radiation from the sub-sources and combine this radiation. The radiation sub-sources may operate simultaneously or alternately. The surfaces may perform functions such as filtering or (de)magnifying.