Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Ultramicroscopy. 2010 Dec;111(1):27-46. doi: 10.1016/j.ultramic.2010.09.007. Epub 2010 Sep 25.
The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests.
以像差参数的形式精确描述仪器成像特性几乎是定量高分辨率透射电子显微镜（HRTEM）的普遍需求，也是该领域中大多数硬件和软件技术的基础。本文重点介绍作为进一步发表 HRTEM 像差测量研究的预备步骤，对单个衍射谱进行数值分析。从衍射谱中提取离焦和双折射像差是一个经典的模式识别问题，我们相信已经以近乎最佳的方式解决了这个问题，在精度、速度和鲁棒性方面都有很好的表现。新获得的测量精度使我们能够分辨离焦和双折射像差的波动，从而评估电子显微镜的光学稳定性。详细阐述了定量稳定性标准，这些标准可以作为日常工作和显微镜验收测试的有用指南。
