Coherence measurements and coherent diffractive imaging at FLASH

* I A Vartanyants (1) , a P Mancuso (1) , A Singer (1) , O M Yefanov (1) , & J Gulden (1)

1 DESY - Deutsches Elektronen-Synchrotron [Hamburg]

We present an overview of recent experiments performed at the free-electron laser (FEL) FLASH at DESY in Hamburg. Experiments were focused on coherence measurements and coherent x-ray diffractive imaging (CXDI) of periodic and non-periodic biological samples. Young's double slit experiment was performed at FLASH to measure its coherence properties at a fundamental wavelength of 13.7 nm. Additionally, a uniformly redundant array (URA) was used to measure coherence properties of the 3 rd harmonic (2.7 nm) of an 8 nm fundamental wavelength at FLASH. Coherent imaging of a two-dimensional (2D) finite crystal structure using a single pulse train of FLASH radiation was demonstrated. We show that the structure is reconstructed to the detector limited resolution of 220 nm, given an adequate signal to noise ratio. We have also employed CXDI in a nondestructive regime to compare images of a biological sample using single, femtosecond pulses of FLASH radiation. We have verified that images reconstructed using CXDI are similar for statistically different FEL pulses. We have also demonstrated Fourier transform holography (FTH) of the same biological sample and present diffraction data measured at the third harmonic of FLASH, reaching into the water window.

Mots clés: free electron laser; coherent imaging; phase retrieval; biological imaging

* I A Vartanyants, a P Mancuso, A Singer, O M Yefanov, & J Gulden. Coherence measurements and coherent diffractive imaging at FLASH. Journal of Physics B: Atomic, Molecular and Optical Physics, 2010, 43 (19), pp.194016. ⟨10.1088/0953-4075/43/19/194016⟩. ⟨hal-00569849⟩