Serial coherent diffraction imaging of dynamic samples based on inter-frame constraint

We proposed a novel approach to coherent imaging of dynamic samples. The inter-frame similarity of the sample's local structures is found to be a powerful constraint in phasing a sequence of diffraction patterns. We devised a new image reconstruction algorithm that exploits this inter-frame constraint enabled by an adaptive similar region determination approach. We demonstrated the feasibility of this technique in visible light experiments with various real samples, achieving reconstructions of good quality within a few hundred iterations. With a setup as simple as conventional coherent diffraction imaging but with much-improved convergence and robustness to missing data and noise, our method is expected to enrich X-ray imaging techniques and electron microscopy, offering a new tool for dynamics studies.

A high-performance reconstruction method for partially coherent ptychography

Ptychography is now integrated as a tool in mainstream microscopy allowing quantitative and high-resolution imaging capabilities over a wide field of view. However, its ultimate performance is inevitably limited by the available coherent flux when implemented using electrons or laboratory X-ray sources. We present a universal reconstruction algorithm with high tolerance to low coherence for both far-field and near-field ptychography. The approach is practical for partial temporal and spatial coherence and requires no prior knowledge of the source properties. Our initial visible-light and electron data show that the method can dramatically improve the reconstruction quality and accelerate the convergence rate of the reconstruction. The approach also integrates well into existing ptychographic engines. It can also improve mixed-state and numerical monochromatisation methods, requiring a smaller number of coherent modes or lower dimensionality of Krylov subspace while providing more stable and faster convergence. We propose that this approach could have significant impact on ptychography of weakly scattering samples.