| Paper | Title | Page |
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| THPD67 | Probing Transverse coherence with the Heterodyne Speckle Approach: Overview and Details | 674 |
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Spatial Coherence properties of radiation produced by accelerated relativistic electrons are far from being trivial. The correct assesment of coherence of High-Brillance X sources (Synchrotron or FEL) is of crucial importance both in machine diagnostics and in experiment planning, in the case coherent techniques are used. Classical methods (Young's interferometer) provides a mild knowledge of the spatial coherence, since probing a wide range of length scales requires long times and the engineerization of ad-hoc test plates. The Heterodyne Speckle Approach [1],[2] is a valuable alternative that exploits the statistical analysis of light scattered by spherical particles. The technique needs a very essential setup composed only by a water suspension of commercial colloidal particles and a CCD camera. Coherence information are retrieved from the Fourier analysis of the interference pattern generated by the stochastic superposition of the waves scattered by the particles and the unperturbed transmitted beam (heterodyne configuration). The technique a) provides a direct measure of transverse coherence without a-priori assumptions, b) provides full 2D coherence map with single-distance measures, c) has been proved to be capable of time-resolved measures with SR sources (ID06, ESRF), d) is potentially scalable over a wide range of walengths (tested 400nm, 0.1nm). It has been used for coherence measures both at the usage point and at the front-end of an undulator source (ID02-ESRF, Grenoble).
[1] M.D. Alaimo, M.A.C. Potenza, M. Manfredda, G. Geloni, M. Sztucki, T. Narayanan & M. Giglio, Phys. Rev. Lett. 103 (2009). [2] M. Manfredda et al., in preparation |
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