基于全变分正则化的原子分辨率STEM图像去噪。

IF 1.5 4区工程技术 Q3 MICROSCOPY

Microscopy Pub Date : 2022-06-17 DOI:10.1093/jmicro/dfac032

Kazuaki Kawahara, R. Ishikawa, Shun Sasano, N. Shibata, Y. Ikuhara

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引用次数: 4

摘要

固体材料的原子分辨率电子显微镜成像是结构分析的一种强大方法。扫描透射电子显微镜（STEM）是直接观察材料中原子的一种常用技术。然而，一些材料很容易被电子束辐照损坏，当我们减少电子剂量以避免电子束损坏时，只有噪声图像可用。因此，对于低剂量STEM中的精确结构分析，去噪过程是必要的。在这项研究中，我们提出了全变分（TV）去噪算法来去除STEM图像中的量子噪声。我们定义了STEM图像的熵，该熵对应于图像对比度以确定超参数，并且我们发现存在使熵最大化的超参数。我们获得了沿[001]方向观察的CaF2的原子分辨率STEM图像，并执行了TV去噪。通过TV去噪，Ca和F的原子柱被清晰地可视化，Ca和F的原子位置被确定，误差分别为±1pm和±4pm。

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Atomic-Resolution STEM Image Denoising by Total Variation Regularization.

Atomic-resolution electron microscopy imaging of solid state material is a powerful method for structural analysis. Scanning transmission electron microscopy (STEM) is one of the actively used techniques to directly observe atoms in materials. However, some materials are easily damaged by the electron beam irradiation, and only noisy images are available when we decrease the electron dose to avoid beam damages. Therefore, a denoising process is necessary for precise structural analysis in low-dose STEM. In this study, we propose total variation (TV) denoising algorithm to remove quantum noise in a STEM image. We defined an entropy of STEM image that corresponds to the image contrast to determine a hyperparameter and we found that there is a hyperparameter that maximize the entropy. We acquired atomic resolution STEM image of CaF2 viewed along the [001] direction, and executed TV denoising. The atomic columns of Ca and F are clearly visualized by the TV denoising, and atomic position of Ca and F are determined with the error of ± 1 pm and ± 4 pm, respectively.

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来源期刊

Microscopy Physics and Astronomy-Instrumentation

CiteScore

3.30

自引率

11.10%

发文量

期刊介绍： Microscopy, previously Journal of Electron Microscopy, promotes research combined with any type of microscopy techniques, applied in life and material sciences. Microscopy is the official journal of the Japanese Society of Microscopy.