Measurement of wavefront and Wigner distribution function for optics alignment and full beam characterization of FELs

Tobias Mey; Bernd Schäfer; Klaus Mann; Barbara Keitel; Svea Kreis; Marion Kuhlmann; Elke Plönjes; Kai Tiedtke

doi:10.1117/12.2016973

3 May 2013 Measurement of wavefront and Wigner distribution function for optics alignment and full beam characterization of FELs

Tobias Mey, Bernd Schäfer, Klaus Mann, Barbara Keitel, Svea Kreis, Marion Kuhlmann, Elke Plönjes, Kai Tiedtke

Author Affiliations +

Proceedings Volume 8778, Advances in X-ray Free-Electron Lasers II: Instrumentation; 87780H (2013) https://doi.org/10.1117/12.2016973
Event: SPIE Optics + Optoelectronics, 2013, Prague, Czech Republic

Abstract

Free-electron lasers deliver EUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on the coherence properties of the beam, for instance when working with coherent di ractive imaging (CDI). Experimentally, we are recovering the phase distribition with an EUV Hartmann wavefront sensor. This allows for online adjustment of focusing optics such as ellipsoidal or Kirkpatrick-Baez mirrors minimizing the aberrations in the focused beam. To gain highly resolved spatial coherence information, we have performed a caustic scan at beamline BL2 of the free-electron laser FLASH using the ellipsoidal focusing mirror and a movable EUV sensitized CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the entire Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and M².

Citation Download Citation

Tobias Mey, Bernd Schäfer, Klaus Mann, Barbara Keitel, Svea Kreis, Marion Kuhlmann, Elke Plönjes, and Kai Tiedtke "Measurement of wavefront and Wigner distribution function for optics alignment and full beam characterization of FELs", Proc. SPIE 8778, Advances in X-ray Free-Electron Lasers II: Instrumentation, 87780H (3 May 2013); https://doi.org/10.1117/12.2016973

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available