Retrieval of material’s 3D structure using new phase-contrast STEM methods
Final Report Abstract
In this project, we aimed at developing new efficient methods for revealing structure information of bulk samples using scanning transmission electron microscopy (STEM). In the first part of the project, we have improved the performance of the current integrated differential phase contrast (IDPC) method by using a cost-efficient solution. This new method allows imaging thick samples without artefacts introduced by anisotropic contrast transfer function (CTF) like in the established method. In order to improve the efficiency of image calculation accounting for the partial coherence of the electron source, we introduced the eigenvector method, which uses a small number of eigenvectors to approximate the mixed envelope function (MEF) accounting for the partial coherence of the source. This method allows for the first time an efficient implementation of the transmission cross coefficient (TCC) model for STEM image calculation, and improved the computational efficiency of the TCC model in TEM image calculation by a factor of 3300 times in our example. The algorithm was successfully implanted in the open-source image simulation package AbTEM. In the second part of the project, we have developed an efficient method for electron ptychography, which retrieves the phase information of a sample within only a few iterations. However, due to the time limitation of the project, an implementation of the method for the in-situ reconstruction of 3D sample information is not available yet.
Publications
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“Integrated Differential Phase Contrast (IDPC)-STEM Utilizing a Multi-Sector Detector for Imaging Thick Samples” Abstract für Dreiländertagung / Microscopy Conference 2021.
Z. Li; J. Biskupek; H. Rose & U. Kaiser
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Integrated Differential Phase Contrast (IDPC)-STEM Utilizing a Multi-Sector Detector for Imaging Thick Samples. Microscopy and Microanalysis, 28(3), 611-621.
Li, Zhongbo; Biskupek, Johannes; Kaiser, Ute & Rose, Harald
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Computationally Efficient Handling of Partially Coherent Electron Sources in (S)TEM Image Simulations via Matrix Diagonalization. Microscopy and Microanalysis, 29(1), 364-373.
Li, Zhongbo; Rose, Harald; Madsen, Jacob; Biskupek, Johannes; Susi, Toma & Kaiser, Ute
