Short note on parallel illumination in the TEM
Short note on parallel illumination in the TEM
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DOI：
10.1016/j.ultramic.2006.04.029
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发表时间：
2006-10-01
期刊：
影响因子：
2.2
通讯作者：
Schattschneider, P.
中科院分区：
文献类型：
--
作者：
Eyidi, D.;Hebert, C.;Schattschneider, P.
透射电子显微镜（TEM）的若干实验需要平行照明条件。电子通过TEM张量磁场的螺旋轨迹引起的像旋转不可避免地引起光束相对于目标平面上的光轴的倾斜——即使对于在远场平行于光轴运动的电子也是如此。这个角（剪切角）向方向加到辐合角上；它取决于到光轴的距离和磁场。利用光束倾斜补偿方法，发现在200 kV瞬变电磁法中，对于2 μ m视场，最小剪切角约为1 μ ad。在实践中，“平行照明”只能在视场中获得
Parallel illumination conditions are required for several experiments in the transmission electron microscope (TEM). The image rotation induced by the helical trajectory of electrons passing through the magnetic field of the TEM tenses inevitably induces an inclination of the beam relative to the optical axis in the object plane-even for an electron which travels parallel to the optical axis in the far field. This angle (shear angle) is vectorially added to the convergence angle; it depends both on the distance to the optical axis and the magnetic field.By using a beam tilt compensation method, the minimum shear angle is found to be of the order of 1 mrad for a field of view of 2 mu m in a 200 kV TEM. In practice, "parallel illumination" can only be obtained for fields of view