Abstract: A method for removing contaminant particles (14), such as atoms, molecules, clusters, ions, and the like, produced by means of a radiation source (10) during generation of short-wave radiation (12) having a wavelength of up to approximately 20 nm, by means of a first gas (22) guided at high mass throughput between the radiation source (10) and a particle trap (20) arranged in a wall (16) of a mirror chamber (18) is described that can be used for a lithography device or a microscope. In order to protect an optical device and/or articles to he irradiated against contamination, the method is designed such that a second gas (24) is introduced into the mirror chamber (18) and its pressure is adjusted such that it is at least as high as the pressure of the first gas (22).