Making the link between ADF and 4D STEM:Resolution,transfer and coherence  

作　　者：Peter D.Nellist Timothy J.Pennycook 

机构地区：[1]Department of Materials,University of Oxford,Oxford,UK [2]EMAT,University of Antwerp,Groenenborgerlaan 171,2020 Antwerp,Belgium

出　　处：《Chinese Physics B》2024年第11期26-33,共8页中国物理B（英文版）

基　　金：funding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Programme via Grant Agreement No.802123-HDEM(TJP);from the UK Engineering and Physical Sciences Research Council(EPSRC)via grant EP/M010708/1(PDN).

摘　　要：Steve Pennycook is a pioneer in the application of high-resolution scanning transmission electron microscopy(STEM)and in particular the use of annular dark-field(ADF)imaging.Here we show how a general framework for 4D STEM allows clear links to be made between ADF imaging and the emerging methods for reconstructing images from 4D STEM data sets.We show that both ADF imaging and ptychographical reconstruction can be thought of in terms of integrating over the overlap regions of diffracted discs in the detector plane.This approach allows the similarities in parts of their transfer functions to be understood,though we note that the transfer functions for ptychographic imaging cannot be used as a measure of information transfer.We also show that conditions of partial spatial and temporal coherence affect ADF imaging and ptychography similarly,showing that achromatic interference can always contribute to the image in both cases,leading to a robustness to partial temporal coherence that has enabled high-resolution imaging.

关 键 词：image forming and processing phase retrieval electron microscopy scanning transmission electron microscope(STEM) 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术] TN16[自动化与计算机技术—计算机科学与技术]