AP Seminar - Electron Ptychography: An Emerging Imaging Technology for Physical and Biological Sciences
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Date
15 Nov 2024
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Organiser
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Time
15:00 - 16:00
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Venue
TU201, 2/F, Wing TU, PolyU Map
Speaker
Dr Peng Wang
Summary
Coherent diffraction imaging (CDI) and ptychography [1] have been widely used in X-ray synchrotron sources. The advantage of ptychography over traditional CDI is that it does not need prior information about the probe function and overcomes some of the other issues of CDI, such as non-unique solutions and a limited field of view.
In electron microscopy, ptychography has also attracted considerable interest due to its potential to achieve super-resolution [1] without using aberration correctors. Unlike conventional imaging modes, the image-forming optics of ptychography replaced by computational methods (like a ‘Digital Lens’) using an array of electron diffractions collected by fast detectors. New generation of direct detection cameras are particularly suited to ptychographic 4D data acquisition with new modes of operation, such as electron counting and fast acquisition. In this talk, I will review the current development and capabilities of this emerging imaging technology (electron ptychography) in my group for light atomic detecting [2], low dose imaging [3], 3D reconstruction [4-5], coupling to spectroscopy [6], EM field mapping, and cryogenic EM [7,8], which can then tackle characterization challenges across the physical and life sciences, ranging from ferroic and battery materials to biological macromolecules. Especially, we introduce an innovative approach called multi-convergence-angle (MCA) ptychography [6], which can simultaneously enhance both contrast and resolution with continuous information transfer across a wide spectrum of spatial frequency. Our work provides feasibility of future applications of MCA-ptychography in providing high-quality two-dimensional images as input to three-dimensional reconstruction methods, thereby facilitating more accurate determination of biological structures.
References:
[1] Rodenburg, J. M. Ptychography and Related Diffractive Imaging Methods. 150, 87-184, (2008).
[2] Wang*, P., et al, Scientific Reports 7, 2857, (2017).
[3] Song, J., …, & Wang*, P. et al. Scientific Reports 9, 3919, (2019).
[4] Gao, S., Wang*, P., et al. Nature Communications 8, 163, (2017).
[5] Ding, Z., …, & Wang*, P., Nature Communications 13, 4787, (2022).
[6] Song, B., …, & Wang*, P., Physical Review Letters 121, 146101, (2018).
[7] Zhou, L., …, & Wang*, P., Nature Communications 11, 2773, (2020).
[8] Pei#, X., …., & Wang*, P., Nature Communications 14, 3027, (2023).
[9] W. Mao, …., & Wang*, P., arXiv 2403.16902 (2024).
Keynote Speaker
Dr Peng Wang
Associate Professor
Department of Physics
University of Warwick
Peng Wang is an associate professor in the Department of Physics at the University of Warwick in the UK. Since 2012, He has held the position of professor leading a Sub-atomic Resolution Electron Microscopy Laboratory at Nanjing University, China. His research interests and strength have been in the applications of aberration-corrected STEM imaging and EELS to characterize advanced functional materials ranging from ceramics and semiconductors to biological materials and nano-materials, at the nano and atomic scales from two to three dimensions. He has also made pioneering contributions to the field of a technique of 3D imaging materials at the nano-scale using scanning confocal EM performed on a double AC-S/TEM. In addition, one of his current works is focused on the advanced coherent diffractive phase imaging technique, so-called Ptychography. His current research has been focused primarily on two areas: developing novel computational diffractive imaging techniques (ptychography, 4D STEM) for cryogenic electron microscopy (Cryo-EM), light atomic detecting (O, Li elements), low dose imaging (beam sensitive materials), 3D reconstruction and EM field mapping, which can then tackle characterization challenges across the physical and life sciences, ranging from battery materials to biological macromolecules. To date, he has published over 150 refereed journal articles. Google Scholar (H-index 57).
