Characterizing the transverse coherence of an undulator beamline at the Advanced Photon Source using grating interferometry

We report on a comprehensive experimental study of the impacts of the quality and stability of optical components on the transverse coherence of the 33-ID beamline at the Advanced Photon Source. More specifIcally, this study, carried out using grating interferometry, shows how the quality of two of the beamline’s key components, namely, the monochromator and the beryllium window, affects the beam transverse coherence and demonstrates that the decoherence effects of each optical component can be measured quantitatively, thus providing critical information for subsequent improvements to the beamline. The technique and analysis used in this work can be adapted to any coherence-oriented beamlines.