An active optics system for EUV/soft x-ray beam shaping

FERMI@Elettra is a VUV/Soft X-ray Free Electron Laser (FEL) user facility under commissioning in Trieste, Italy. It provides a spatially coherent transform-limited photon beam in the sub-ps regime with high fluence and tunable wavelength. One of the FERMI beamlines, TIMEX, will be dedicated to the study of matter under extreme and metastable conditions, created and probed by the FEL radiation. Moreover, an active optics dedicated to perform the beam shaping at focus is needed in order to provide the necessary flat-top intensity distribution for heating the sample uniformly. In this work the principles of the beam shaping applied to the TIMEX beamline will be discussed as well as the adopted solution. Ray tracing simulations will be shown for theoretical mirror profiles as well as the metrological measurements with an interferometer and the Long Trace Profiler (LTP).