Center for High-Resolution Electron Microscopy, College of Materials Science & Engineering, Hunan University, Changsha, Hunan 410082, China.
Center for High-Resolution Electron Microscopy, College of Materials Science & Engineering, Hunan University, Changsha, Hunan 410082, China.
Micron. 2022 Jun;157:103247. doi: 10.1016/j.micron.2022.103247. Epub 2022 Mar 16.
Measuring residual aberrations up to second order using a crystalline specimen in transmission electron microscope is challenging. Here, we show by good examples of both experimental and simulated images that it is feasible to measure aberrations up to the second-order, using minimum amplitude contrast criterion for the exit wave function reconstructed. We propose a two-steps strategy for the task: (i) Firstly measuring defocus and two-fold astigmatism simultaneously to avoid error accumulation and to reduce the number of dimensions in parameters space. (ii) Then, with minimized misleading effects (or errors) in defocus and two-fold astigmatism, estimations of three-fold astigmatism and coma can be conducted more efficiently and effectively. Influences of other factors such as specimen structure, resolution and specimen thickness on the validity of the method are also discussed in detail. Our study provides a practical procedure for correcting residual aberrations in image wave using crystalline materials, which can then facilitate application of exit wave reconstruction technique to materials research.
使用透射电子显微镜中的晶体标本测量二阶残余像差极具挑战性。在这里，我们通过实验和模拟图像的实例展示了使用重建的出射波函数的最小振幅对比度准则来测量二阶像差是可行的。我们为该任务提出了两步策略：(i) 首先同时测量离焦和双折射像散，以避免误差累积并减少参数空间的维数。(ii) 然后，在最小化离焦和双折射像散的误导影响（或误差）的情况下，更有效地进行三阶像散和彗差的估计。还详细讨论了标本结构、分辨率和标本厚度等其他因素对该方法有效性的影响。我们的研究为使用晶体材料校正图像波中的残余像差提供了一种实用的方法，从而促进了出射波重建技术在材料研究中的应用。
