WW-Colloquium: Prof. Georgios Varnavides – Dose-Efficient Diffractive Imaging with Electrons

Prof. Georgios Varnavides
Delft University of Technology, Netherlands
Dose-Efficient Diffractive Imaging with Electrons

High-resolution characterization underpins modern materials science, linking structure and dynamics across length scales. Yet, while structural imaging has advanced dramatically, mapping functional fields—such as charge, heat, and spin currents—at comparable resolution remains a major challenge. Many materials of interest, from quantum heterostructures to biological and soft matter systems, are further limited by weak scattering or radiation sensitivity. More dose-efficient imaging approaches are therefore essential, both to reveal fragile nanoscale order and to probe subtle transport and quantum phenomena.

In this interactive talk, I will introduce computational diffractive imaging with electrons—a framework that reconstructs information from scattered electron patterns using physics-based inverse algorithms—as a pathway to overcome these limitations. I will frame the method as an inverse scattering problem and compare the efficiency and sensitivity of various computational imaging strategies. Particular emphasis will be placed on their implications for time-resolved studies and for imaging quantum and functional materials. I will highlight the conceptual connection between iterative and direct ptychography, show how tilt-corrected bright-field STEM emerges as a quadratic approximation to direct ptychography, and present a new algorithm that enables robust information recovery from sub-sampled measurements.