• M.A. Bowler
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• B. Faatz, K.I. Tiedtke
  DESY, Hamburg
• F. Siewert
  BESSY GmbH, Berlin

Imperfections on the surfaces of the optical components of photon transport systems can degrade the quality of the radiation, causing amongst other effects structure in the transverse beam profile. This effect is being investigated for one of the beamlines at FLASH. The FEL mirror surfaces have been measured in the metrology laboratory at Helmholtz Zentrum Berlin / BESSY-II, and these data are input into wavefront propagation calculations, which model the transport of the radiation field from the exit of the FEL across the optics to the experiment. The input fields for the propagation were generated using the Genesis1.3 code. This work is part of collaboration in the IRUVX-PP consortium.