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在会聚束衍射中(CBED).晶体点群和空间群的标准测量方法需要四种类型的图象(正常衍射图,明埸象,暗场象和±G暗场象).在同一胶片上同时获取四种图象的方法已经报导过(JEOL,NEWS,24E.62,1986)。然而该方法所需要的样品必须具有1μm直径,相同厚度,无弯曲的薄区。因此此,法不适用于实际应用.本文介绍一种从样品中100nm直径薄区获得这些图象的具有使用价值的方法.该方法是通过调节物镜励磁电流和中间镜励磁电流来观察的:它的应用结果也作相应的描述。
In convergent beam diffraction (CBED), four types of images (normal diffraction pattern, bright image, dark image, and ± dark field image) are required for the standard measurement of crystal point and space groups. On the same film The method of acquiring four images simultaneously has been reported (JEOL, NEWS, 24E.62, 1986). However, the sample required for this method must have a 1 μm diameter, the same thickness, and a thin, uncurved area. Therefore, the method is not suitable for practical applications.This paper presents a useful method for obtaining these images from a thin film of 100 nm in diameter in a sample by adjusting the objective field current and the intermediate field current: The application results are also described accordingly.