Evaluation of partial coherence correction in X-ray ptychography

Coherent X-ray Diffraction Imaging (CDI) and X-ray ptychography both heavily rely on the high degree of spatial coherence of the X-ray illumination for sufficient experimental data quality for reconstruction convergence. Nevertheless, the majority of the available synchrotron undulatorsources have a limited degree of partial coherence, leading to reduced data quality and a lower speckle contrast in the coherent diffraction patterns.It is still an open question whether experimentalists should compromise the coherence properties of an X-ray source in exchange for a higher fluxdensity at a sample, especially when some materials of scientific interest are relatively weak scatterers. A previous study has suggested that in CDI,the best strategy for the study of strong phase objects is to maintain a high degree of coherence of the illuminating X-rays because of the broadeningof solution space resulting from the strong phase structures. In this article, we demonstrate the first systematic analysis of the effectiveness of partialcoherence correction in ptychography as a function of the coherence properties, degree of complexity of illumination (degree of phase diversityof the probe) and sample phase complexity. We have also performed analysis of how well ptychographic algorithms refine X-ray probe andcomplex coherence functions when those variables are unknown at the start of reconstructions, for noise-free simulated data, in the case of bothreal-valued and highly-complex objects