title: Spatio-temporal coherence of free electron laser pulses in the soft x-ray regime.
abstract: The temporal coherence properties of soft x-ray free electron laser pulses at FLASH are measured at 23.9 nm by interfering two time-delayed partial beams directly on a CCD camera. The partial beams are obtained by wave front beam splitting in an autocorrelator operating at photon energies from h nu = 30 to 200 eV. At zero delay a visibility of (0.63+/- 0.04) is measured. The delay of one partial beam reveals a coherence time of 6 fs at 23.9 nm. The visibility further displays a non-monotonic decay, which can be rationalized by the presence of multiple pulse structure.
authors.affiliation: Physikalisches Institut, Westfälische Wilhelms-Universität, 48149 Münster, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Mitzner
authors.forename: B
authors.initials: B
authors.lastname: Siemer
authors.forename: M
authors.initials: M
authors.lastname: Neeb
authors.forename: T
authors.initials: T
authors.lastname: Noll
authors.forename: F
authors.initials: F
authors.lastname: Siewert
authors.forename: S
authors.initials: S
authors.lastname: Roling
authors.forename: M
authors.initials: M
authors.lastname: Rutkowski
authors.forename: A A
authors.initials: AA
authors.lastname: Sorokin
authors.forename: M
authors.initials: M
authors.lastname: Richter
authors.forename: P
authors.initials: P
authors.lastname: Juranic
authors.forename: K
authors.initials: K
authors.lastname: Tiedtke
authors.forename: J
authors.initials: J
authors.lastname: Feldhaus
authors.forename: W
authors.initials: W
authors.lastname: Eberhardt
authors.forename: H
authors.initials: H
authors.lastname: Zacharias