Wavefront and nanostructure characterisation with X-ray ptychography

Authors: Simone Sala (University College London (UCL))
Co-authored by industrial partner: No

Type: Thesis

State: Published (Approved)
Published: December 2018

Abstract: X-ray ptychography is a scanning di raction microscopy technique suited for the phase-sensitive investigation of wavefronts and specimens. It returns complex-valued wave functions and transmission functions producing high-resolution (nanoscale) phasecontrast images. This work focuses on the implementation and application of X-ray ptychography in the context of synchrotron radiation facilities. It presents an experimental protocol developed for multiscale X-ray imaging and tested at the I13-1 Coherence Branchline at Diamond Light Source. This protocol combines both near- eld and far- eld ptychography with other imaging methods, providing a exible way of conducting experiments on hierarchical structures at any high-brilliance X-ray facility. This work also reports ptychography experiments performed at free-electron lasers, aimed at characterising their pulsed beam. Both the average and individual wavefronts are retrieved through a novel application of a reconstruction algorithm based on singularvalue decomposition, giving direct insight on pulse-to-pulse uctuations and con rming ptychography as a powerful beam diagnostics technique. Additional ptychography experiments are also discussed, which were carried out at storage rings on at, weakly-scattering biogenic samples to characterise their 3D nanostructures. Their data analysis pipeline is presented in detail, from data acquisition to rendered volumes. Furthermore, one of these last experiments constitutes the rst successful 3D ptychography experiment run on real-life samples at the I13-1 Coherence Branchline at Diamond Light Source.

Subject Areas: Physics

Beamlines: I13-1-Coherence