Improved Three-Dimensional Reconstructions in Electron Ptychography through Defocus Series Measurements

作者：Marcel Schloz, Thomas C. Pekin, Hamish G. Brown, Dana O. Byrne, Bryan D. Esser, Emmanuel Terzoudis-Lumsden, Takashi Taniguchi, Kenji Watanabe, Scott D. Findlay, Benedikt Haas, Jim Ciston, Christoph T. Koch · 发表于：Microscopy and Microanalysis · 年份：2024 · DOI：10.1093/mam/ozae110 · 被引用次数：5 · 研究领域：Advanced X-ray Imaging Techniques、Particle Accelerators and Free-Electron Lasers、Crystallography and Radiation Phenomena

A detailed analysis of ptychography for three-dimensional (3D) phase reconstructions of thick specimens is performed. We introduce multi-focus ptychography, which incorporates a 4D-STEM defocus series to enhance the quality of 3D reconstructions along the beam direction through a higher overdetermination ratio. This method is compared with established multi-slice ptychography techniques, such as conventional ptychography, regularized ptychography, and multi-mode ptychography. Additionally, we contrast multi-focus ptychography with an alternative method that uses virtual optical sectioning through a reconstructed scattering matrix (S-matrix), which offers more precise 3D structure information compared to conventional ptychography. Our findings from multiple 3D reconstructions based on simulated and experimental data demonstrate that multi-focus ptychography surpasses other techniques, particularly in accurately reconstructing the surfaces and interface regions of thick specimens.