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Updated: May 18, 2026
09:49
An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers
Published on: October 23, 2018
Spatial and temporal coherence properties of single free-electron laser pulses
A Singer1, F Sorgenfrei, A P Mancuso
1Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg, Germany.
Optics Express
|October 6, 2012
Summary
Researchers experimentally characterized the spatial and temporal coherence of the Free-Electron Laser in Hamburg (FLASH) at 8.0 nm. The study determined coherence lengths and times, revealing a high degeneracy parameter exceeding other sources.
Area of Science:
- Coherent X-ray science
- Ultrafast laser physics
- Synchrotron radiation
Background:
- Free-electron lasers (FELs) are advanced light sources producing coherent radiation.
- Understanding the coherence properties of FELs is crucial for advanced applications.
- The Free-Electron Laser in Hamburg (FLASH) is a prominent soft X-ray FEL facility.
Purpose of the Study:
- To experimentally determine the spatial and temporal coherence of the FLASH facility at a wavelength of 8.0 nm.
- To quantify the transverse coherence length and coherence time of femtosecond pulses from FLASH.
- To estimate the degeneracy parameter of the FLASH beam and compare it with other sources.
Main Methods:
- Measurement of double pinhole diffraction patterns from single femtosecond pulses.
- Focusing of FEL pulses to approximately 10x10 μm(2).
- Utilizing a split and delay unit to measure pulse coherence time.
Main Results:
- Determined transverse coherence lengths of 6.2 ± 0.9 μm (horizontal) and 8.7 ± 1.0 μm (vertical).
- Measured a coherence time of 1.75 ± 0.01 fs for FLASH pulses.
- Estimated a high degeneracy parameter (10^10 to 10^11) for the FLASH beam.
Conclusions:
- FLASH exhibits significant spatial and temporal coherence at 8.0 nm.
- The measured coherence properties are superior to other sources in the same energy range.
- These findings highlight FLASH's potential for advanced coherent X-ray applications.
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