DiProI Research

Coherent Diffraction Imaging proof of principle

In March 2012 the performance of the K-B mirror focusing optics, designed to provide a 3x5 µm² microprobe, reached some modest microprobe of 40×50 µm² with preserved coherence. This allowed us to perform the first proof-of-principle single-shot CDI and holography imaging of nano-lithographic test objects, fabricated on Si₃N₄ windows. The intensity of the photons scattered from the objects was monitored on a CCD camera using a detection set-up with a 45° multilayer (for 32.5 nm) mirror.The speckle pattern of the ‘Christmas tree’ object was obtained in a single-shot mode (pulse energy ~20 µJ and wavelength 32.5 nm). Although the object was destroyed by this intense FEL pulse, the information contained in the diffraction pattern was sufficient for reconstruction of the object image by recovering the missing phase information using computational algorithm. Similar successful CDI experiments with other test samples have confirmed that the Fermi@Elettra FEL-1 peak intensity, coherence and pulse duration are sufficient for performing ultrafast coherent diffraction imaging of non-periodic nano-objects, obtaining the necessary structural information before the radiation damage has occurred. 

First proof of principle CDI experiment performed at the DiProI beamline with an indirect detection geometry. The image is reconstructed through phase retrieval algorithm.