Synchrotron coherence measurements utilizing Non-Redundant Arrays of slits

We present a method to characterize the spatial coherence of soft X-ray radiation from a single diffraction pattern. The technique is based on scattering from non-redundant arrays (NRA) of slits and records the degree of spatial coherence at several relative separations [1]. Using NRAs we measured the spatial coherence of the X-ray beam at the XUV X-ray beamline P04 of the PETRA III storage ring [2] and at the U49/2 PGM1 beamline of the BESSY II synchrotron [3]. In both cases, the spatial coherence was measured for different beam parameters, including the photon energy and the monochromator exit slits separation (see Fig.1). We demonstrated that a rapid high-throughput analysis of the beam spatial coherence prior to any experiment utilizing coherence is possible. We also foresee that NRA method could become a viable tool for single pulse coherence characterization measurements at X-ray free-electron lasers [4, 5].References:[1] Y. Mejía et al., Opt. Commun. 273, 428 (2007).[2] P. Skopintsev et al., J. Synchrotron Rad. (2014) (accepted).[3] P. Skopintsev et al. (2014) (in preparation)[4] I.A. Vartanyants et al., Phys. Rev. Lett. 107, 144801 (2011).[5] A. Singer et al., Opt. Express 20(16), 17480 (2012)