Front-coupling of a prefocused x-ray beam into a monomodal planar waveguide

A hard x-ray beam of photon energy E=12.5 keV has been focused by a Kirkpatrick-Baez mirror system and coupled into the front side of a single-mode x-ray waveguide. The beam dimensions of 3.8x2.5 mum(2) in the focus of the mirror system have thus been reduced in one direction to 32 nm, corresponding to the guiding layer thickness of the waveguide. At the same time the waveguide acts as a coherence filter and leads to a well-defined intensity distribution with steep tails in the near- and far-field regions. The total flux transmitted by the waveguide exceeded 10(8) photons/s while no significant contributions of radiation transmitted through the absorbing waveguide cladding have been observed. (C) 2004 American Institute of Physics.