Mapping the transverse coherence of the self amplified spontaneous emission of a free-electron laser with the heterodyne speckle method

Opt Express. 2014 Dec 1;22(24):30013-23. doi: 10.1364/OE.22.030013.


The two-dimensional single shot transverse coherence of the Self-Amplified Spontaneous Emission of the SPARC_LAB Free-Electron Laser was measured through the statistical analysis of a speckle field produced by heterodyning the radiation beam with a huge number of reference waves, scattered by a suspension of particles. In this paper we report the measurements and the evaluation of the transverse coherence along the SPARC_LAB undulator modules. The measure method was demonstrated to be precise and robust, it does not require any a priori assumptions and can be implemented over a wide range of wavelengths, from the optical radiation to the x-rays.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amplifiers, Electronic*
  • Computer Simulation
  • Electrons*
  • Lasers*
  • Models, Theoretical
  • Optics and Photonics / methods*
  • Thermodynamics