Beam-splitting and recombining of free-electron-laser extreme-ultraviolet radiation

The design of systems for the splitting of the radiation from a free-electron-laser (FEL) in the extreme-ultraviolet spectral region is presented. Systems for the beam-splitting of the FEL radiation are important, both for having the light available simultaneously to several experiments, and for the division and recombination of the beam (pump-probe techniques). We present systems with a grazing-incidence plane grating, which is illuminated by the single FEL beam and gives several output beams (the zero order and the diffracted orders). The grating gives intrinsically a time stretching of the diffracted beam, so time-compensated configurations are used. Systems for the splitting of the primary beam in two secondary beams and for the splitting and recombining from two beams with variable delay are presented. PACS 41.60.Cr; 42.79.Dj; 42.79.Fm