FEL2012 - List of Authors (Potenza, M.A.C.)

Paper

Title

Page

Measurement of the Transverse Coherence of the Sase FEL Radiation in The Optical Range Using an Heterodyne Speckle Method

551

M.D. Alaimo, M. Manfredda, M.A.C. Potenza, D. Redoglio
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, V. Surrenti, A. Torre
ENEA C.R. Frascati, Frascati (Roma), Italy
M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy

An heterodyne speckle approach has been applied for measuring the transverse coherence of FEL radiation in SASE regime in the optical region (400nm) at SPARC (LNF, Frascati - Italy). It turned out that the coherence length is comparable with the beam size and only slight variations of the coherence properties have been observed after the 5th undulator section. The technique needs a very essential setup composed only by a water suspension of commercial colloidal particles and a CCD camera. The Complex Coherence Factor is retrieved from the Fourier analysis of the interference pattern generated by the stochastic superposition of the almost spherical waves scattered by the particles and the unperturbed transmitted beam (heterodyne speckles). This approach does not require the engineering of ad-hoc devices and provides a two-dimensional map of the transverse coherence without any a-priori assumption about its functional form. The method is suitable for one-shot characterization and it works in the X-ray wavelength as well. It has been previously developed and tested to be effective with synchrotron radiation [*,**] (ID02 and ID06 at ESRF, Grenoble).
* M.D. Alaimo, M.A.C. Potenza, M. Manfredda, G. Geloni, M. Sztucki, T. Narayanan & M. Giglio, Phys. Rev. Lett. 10³ (2009).
** M. Manfredda et al., in preparation

Slides THOC03 [8.489 MB]

THPD67

Probing Transverse coherence with the Heterodyne Speckle Approach: Overview and Details

674

M. Manfredda, M.D. Alaimo, M.A.C. Potenza
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Giglio
Università degli Studi di Milano, Milano, Italy

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

Paper	Title	Page
THOC03	Measurement of the Transverse Coherence of the Sase FEL Radiation in The Optical Range Using an Heterodyne Speckle Method	551
	M.D. Alaimo, M. Manfredda, M.A.C. Potenza, D. Redoglio Universita' degli Studi di Milano & INFN, Milano, Italy M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, V. Surrenti, A. Torre ENEA C.R. Frascati, Frascati (Roma), Italy M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy V. Petrillo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy
	An heterodyne speckle approach has been applied for measuring the transverse coherence of FEL radiation in SASE regime in the optical region (400nm) at SPARC (LNF, Frascati - Italy). It turned out that the coherence length is comparable with the beam size and only slight variations of the coherence properties have been observed after the 5th undulator section. The technique needs a very essential setup composed only by a water suspension of commercial colloidal particles and a CCD camera. The Complex Coherence Factor is retrieved from the Fourier analysis of the interference pattern generated by the stochastic superposition of the almost spherical waves scattered by the particles and the unperturbed transmitted beam (heterodyne speckles). This approach does not require the engineering of ad-hoc devices and provides a two-dimensional map of the transverse coherence without any a-priori assumption about its functional form. The method is suitable for one-shot characterization and it works in the X-ray wavelength as well. It has been previously developed and tested to be effective with synchrotron radiation [,] (ID02 and ID06 at ESRF, Grenoble). M.D. Alaimo, M.A.C. Potenza, M. Manfredda, G. Geloni, M. Sztucki, T. Narayanan & M. Giglio, Phys. Rev. Lett. 10³ (2009). ** M. Manfredda et al., in preparation
	Slides THOC03 [8.489 MB]

THPD67	Probing Transverse coherence with the Heterodyne Speckle Approach: Overview and Details	674
	M. Manfredda, M.D. Alaimo, M.A.C. Potenza Universita' degli Studi di Milano & INFN, Milano, Italy M. Giglio Università degli Studi di Milano, Milano, Italy
	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