Spatio-temporal coherence of free electron laser pulses in the soft x-ray regime.
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.
Mitzner
R
R
Physikalisches Institut, Westfälische Wilhelms-Universität, 48149 Münster, Germany.
Siemer
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B
Neeb
M
M
Noll
T
T
Siewert
F
F
Roling
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Rutkowski
M
M
Sorokin
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AA
Richter
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Juranic
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Tiedtke
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Feldhaus
J
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Eberhardt
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Zacharias
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