skip to main content


Title: Microfocusing at the PG1 beamline at FLASH

The Kirkpatrick–Baez (KB) refocusing mirror system installed at the PG1 branch of the plane-grating monochromator beamline at the soft X-ray/XUV free-electron laser in Hamburg (FLASH) is designed to provide tight aberration-free focusing down to 4 µm × 6 µm full width at half-maximum (FWHM) on the sample. Such a focal spot size is mandatory to achieve ultimate resolution and to guarantee best performance of the vacuum-ultraviolet (VUV) off-axis parabolic double-monochromator Raman spectrometer permanently installed at the PG1 beamline as an experimental end-station. The vertical beam size on the sample of the Raman spectrometer, which operates without entrance slit, defines and limits the energy resolution of the instrument which has an unprecedented design value of 2 meV for photon energies below 70 eV and about 15 meV for higher energies up to 200 eV. In order to reach the designed focal spot size of 4 µm FWHM (vertically) and to hold the highest spectrometer resolution, special fully motorized in-vacuum manipulators for the KB mirror holders have been developed and the optics have been aligned employing wavefront-sensing techniques as well as ablative imprints analysis. Lastly, aberrations like astigmatism were minimized. In this article the design and layout of the KB mirror manipulators,more » the alignment procedure as well as microfocus optimization results are presented.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [1] ;  [1]
  1. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
  2. European XFEL GmbH, Hamburg (Germany)
  3. Univ. of South Florida, Tampa, FL (United States)
  4. Laser-Laboratorium Gottingen e.V., Gottingen (Germany)
  5. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  6. Univ. of Hamburg (Germany). Center for Free-Electron Laser Science
  7. Helmholtz Zentrum Berlin (BESSY II), Berlin (Germany)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; EMRPJRP SIB58
Accepted Manuscript
Journal Name:
Journal of Synchrotron Radiation (Online)
Additional Journal Information:
Journal Name: Journal of Synchrotron Radiation (Online); Journal Volume: 23; Journal Issue: 1; Journal ID: ISSN 1600-5775
International Union of Crystallography
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 43 PARTICLE ACCELERATORS; Kirkpatrick–Baez mirror system; free-electron laser; microfocus; plane-grating monochromator beamline
OSTI Identifier: