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.