STROBE Seminar: “EUV Ptychography: Advancing Material-Specific Imaging at the Nanoscale”

Abstract: While electron microscopy enables imaging of individual atoms, the sample thickness is typically limited to a few hundred nanometers. Although super-resolution optical microscopy permits high-resolution visualization of subcellular structures, it requires staining of the sample. In contrast, EUV and X-ray microscopy allow imaging of entire biological cells and other thick specimens with spatial resolutions down to ~10 nm.

In recent years, a new class of laser-driven, coherent EUV and soft X-ray sources based on high harmonic generation has been developed. These sources now make it possible to perform high-resolution coherent imaging experiments on a laboratory scale, which were previously restricted to large research facilities such as synchrotrons. In this talk, we will demonstrate high-resolution quantitative microscopy using EUV ptychography on a laboratory scale. We will also discuss how elemental composition can be extracted from these images, as illustrated with microbiological model organisms such as Aspergillus nidulans and Escherichia coli. Additionally, first results of imaging with higher photon energies in the soft X-ray spectral range will be presented, paving the way for future studies of intact biological samples in a near-native state at resolutions below 50 nm.

Bio: Wilhelm Eschen is a Postdoctoral Research Associate at JILA in Boulder, where he continues his work at the forefront of coherent EUV and soft X-ray imaging. He earned his Ph.D. from Friedrich-Schiller-University Jena in 2024, completing his dissertation on high-resolution EUV ptychography using high-order harmonic sources under the supervision of Jan Rothhardt and Jens Limpert. During his doctoral studies, he received several distinctions for his research, including the Dr.-Ing. Siegfried Werth Prize for outstanding scientific achievement in high-resolution microscopy and the ZEISS Ph.D. Award in Modern Optics for excellence in optical science and technology. His current research focuses on extending laboratory-scale coherent imaging into the soft X-ray spectral range, enabling high-resolution table-top studies of thick biological and material samples with unprecedented elemental contrast and resolution.