Blind Multi-Mode Ptychography using a Distributed Probe Estimate

Ptychography uses overlapping X-ray diffraction measurements to perform nanometer-scale imaging of objects. Practical illumination sources for ptychography, such as synchrotrons, are not fully coherent, so they exhibit multiple modes. To address this, blind multi-mode ptychography algorithms have been developed that jointly estimate the image along with the multiple probe modes. However, commonly used algorithms, such as DM and SHARP, use a single global estimate of the probe state that does not allow for local spatial variation in the probe.In this paper, we compare a distributed probe state version of the BM-PMACE algorithm to a global probe state version of BM-PMACE as well as to DM and SHARP. Importantly, distributed state BM-PMACE maintains a location-specific probe state that captures spatially varying probe aberrations. Using measured data, we demonstrate that the distributed probe state improves both convergence speed and final image quality compared to the global state algorithms.