Si Gao, Fucai Zhang, AI Kirkland, Xiaoqing Pan, Peng Wang，“Towards 3D electron ptychographic reconstruction”，Microscopy and Microanalysis 22 (S3), 464-465（2017）

【原文】

Towards 3D electron ptychographic reconstruction

ABSTRACT

Transmission electron microscope (TEM) is a powerful tool for material science due to its high spatial resolution. Coherent diffraction imaging (CDI)[1] is a "lensless" method that forms an image of an object by solving the phase problem from a single diffraction pattern with an iterative computer algorithm. This approach can, in principle, overcome the current image resolution limiting factors and ultimately achieve wavelength-limited resolution. However, conventional CDI requires an isolated sample and a priori knowledge about its shape or extent. Rodenburg suggested an extended ptychographical iterative engine (ePIE), which does not need this prior information and overcomes many of the other issues of CDI, such as non-unique solutions, limited field of view, etc. Recently, twodimensional (2D) ptychographical reconstructions with atomic lateral resolution [2] have been achieved using ePIE [3] on a CeO2 nanoparticle. However, when the sample becomes thicker, the multiplicative assumption of electron-sample interaction becomes invalid causing the ptychographical reconstruction to breakdown. To overcome this limitation, Maiden et al cooperated the well-known multiple slice calculation procedure into the ePIE algorithm (3PIE) [4] in which a sample is split into axial sections, to produce 3D optically sectioned images of the sample. This 3D multiple-section reconstruction of ptychography has been successfully demonstrated in both light [4] and X-ray [5] optics recently. However, this method still remains challenging for the electron case.