电子双棱镜的衍射对离轴电子全息图的影响

Influence of the Diffraction of an Electron Biprim on Off-axis Electron Holograms

提出了一种用计算机模拟离轴电子全息图的方法。在该方法中 ,首先计算样品在物镜像平面的波函数 ,再逆向传播到电子双棱镜平面 ,在计算棱镜面的抽样时加上棱镜对电子波的偏转和棱镜丝的影响。由于考虑到了电子双棱镜超细丝的菲涅耳衍射对干涉图样的影响 。

A method of simulating off axis electron holograms by computers is presented.In this method,the object wave on the image plane is calculated firstly,taking into account the transfer function of the image system.Then it is transmitted back to the biprism plane,on which the influence of the electron biprism on the object wave is added.By this way,the influence of the filament in the electron biprism on off axis electron hologram because of its Fresnel diffraction can be considered.Some simulated results consistent with experiments and some reference data for quantitatively analyzing the electron hologram are given.At the end,a possible approach of decreasing the influence of the Fresnel diffraction on the off axis hologram is discussed.