Lensless Imaging Using Atto/Femtosecond Coherent X-Ray Sources
July 8th, 2019 HAMED MERDJI Lasers, Interactions and Dynamics Laboratory, CEA Saclay

Imaging individual objects, with angström/nanometer resolution in space and atto/femtosecond resolution in time is of fundamental importance in many areas of science and represents today a fascinating challenge. In such context, lensless methods using coherent ultrashort X-ray sources has demonstrated a high potential. Imaging based on coherent diffraction overcomes many restrictions in imaging offering means to produce images of non-crystalline objects at a resolution, in principle, limited by the wavelength only. Basically, a spatially coherent X-ray beam illuminates a sample and the far-field diffraction pattern of the object is recorded on an area detector. Since the detector records only the diffracted intensities the “real image” is retrieved from the amplitude and phase diffraction pattern using various phase retrieval approaches such as holography, phase retrieval imaging, ptychography, 3D imaging. Active research is currently pushing the capability of these techniques using recently available short-pulse coherent X-ray sources such as high harmonics generation and X-ray free electron lasers. We will in particular present recent challenge related to the broadband nature of attosecond sources.

Seminar, July 8-9, 2019, 16:30. ICFO’s Auditorium