X-ray ptychography

Abstract

Hard X-ray lens-less microscopy holds the promise of a resolution power meeting the need of nanoscience, owing to the possibility of circumventing the limits of state-of-the-art X-ray lenses [1].Beyond the resolution issue, the complex-valued wavefield is imaged, hence ensuring truly quantitative information on the sample scattering contrast.Furthermore, combining this approach to the Bragg geometry allows providing images of defects and strains in nanocrystals, in a non-destructive manner [2].Lens-less microscopy makes use of far-field coherent intensity patterns produced by third generation synchrotron sources.Instead of lenses, numerical approaches are employed to retrieve the exit-field at the sample position [1].An overview of the capabilities and the actual limits will be given in this presentation, in the specific case of crystalline imaging.In particular Bragg coherent diffraction imaging, Fourier transform holography [3] and ptychography [4] will be discussed and compared.The accurate and detailed knowledge of the crystalline structures at the nanoscale is highly desirable for its potential to bring new insight and understanding in a large variety of nanoscience material problems: this challenge is expected to be met by Bragg lens-less X-ray microscopy.