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.