With the technical breakthroughs of creating oxides by novel thin film deposition techniques with well-defined interfaces, oxides have received increasing attention in the electronic and optoelectronic industry due to their unique com⁃bination of novel physical properties and the fact that oxides can form “heterostructures” for multiple devices. In order to understand the atomic/electronic structure in oxide interfaces, various characterization techniques have been involved. In the past, the characterization has been limited to broad beam techniques though X⁃ray absorption spectroscopy ( XAS) , nuclear magnetic resonance ( NMR) to achieve the average physical and chemical information. With techniques such as scanning transmission electron microscopy ( STEM) and electron energy⁃loss spectroscopy ( EELS) , high⁃resolution TEM opens the path to the study of chemical composition and bonding information coupled with the atomic level images, and thus provides an ideal tool to investigate individual interface. Interface can�t be physically isolated from the bulk, it is diffi⁃cult to correctly and effectively extract the weak signal from these interfaces presented in a solid bulk. Such extraction re⁃mains a very challenging issue even in TEM when thin foils, with thickness less than 100 nm, are used. The visibility of these interfaces can be enhanced by picking up corresponding signals since the elastically scattered electrons contributing to signals from these interfaces are distributed unevenly in space and differently compared to the ones contributed by the bulk. Studying cross⁃sectional samples provides two⁃dimensional projected information of the three⁃dimensional interfacial structures. Accordingly, the atomic structure can be constructed through combining information from different projections. Regarding the fact that EELS signals from the defects and the bulk are distributed similarly in space, a new experimental approach, based on a “thickness” series of EEL spectra containing different bulk contributions, was proposed to effectively extract weak EELS signals from these interfaces. The development of characterization techniques such as TEM has led to improved understanding of oxide interfaces and thus provides great opportunity to create artificial structure for their novel physical properties.%随着薄膜制备技术的发展和理想氧化物界面的实现，氧化物界面表现出如超导性等诸多优异特性，成为新一代电子器件的有力候选材料。相较金属和半导体界面而言，氧化物界面的特性更具有局域性，故阐明其界面处的原子／电子结构显得更为重要。界面并不能独立于体相而单独存在，因此研究界面问题的关键是如何提取掩埋在体相中的微弱界面信息。透射电子显微镜作为一种表征局域结构的手段，同时又具备多种技术可实现成像、衍射以及能谱分析，故成为表征氧化物界面的有力工具。通过制备截面样品，可得到氧化物界面在不同投影面的二维结构，进而重构界面的三维原子结构。此外，通过采集包含不同比重界面信号的一组实验数据，可通过数学分析方法分离出界面信号。这种方法在研究界面和界面的电子结构等问题上具有一定优势。
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