Characterization of the X-ray coherence properties of an undulator beamline at the Advanced Photon Source

Guangxu Ju, Matthew J. Highland, Carol Thompson, Jeffrey A. Eastman, Paul H. Fuoss, Hua Zhou, Roger Dejus, G. Brian Stephenson

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


In anticipation of the increased use of coherent X-ray methods and the need to upgrade beamlines to match improved source quality, here the coherence properties of the X-rays delivered by beamline 12ID-D at the Advanced Photon Source have been characterized. The measured X-ray divergence, beam size, brightness and coherent flux at energies up to 26 keV are compared with the calculated values from the undulator source, and the effects of beamline optics such as a mirror, monochromator and compound refractive lenses are evaluated. Diffraction patterns from slits as a function of slit width are analyzed using wave propagation theory to obtain the beam divergence and thus coherence length. Imaging of the source using a compound refractive lens was found to be the most accurate method for determining the vertical divergence. While the brightness and coherent flux obtained without a monochromator (`pink beam') agree well with those calculated for the source, those measured with the monochromator were a factor of three to six lower than the source, primarily because of vertical divergence introduced by the monochromator. The methods described herein should be widely applicable for measuring the X-ray coherence properties of synchrotron beamlines.

Original languageEnglish (US)
Pages (from-to)1036-1047
Number of pages12
JournalJournal of synchrotron radiation
Issue number4
StatePublished - Jul 2018


  • brightness
  • coherence
  • divergence

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Instrumentation


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