Quantum Dot Research Center, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0005, Japan.
Ultramicroscopy. 2010 Dec;111(1):20-6. doi: 10.1016/j.ultramic.2010.08.004.
Imaging properties of scanning confocal electron microscopy (SCEM) were studied by calculating simple model systems using the multislice method. A simple geometrical explanation was given, particularly for the difference between bright field (BF) and annular dark field (ADF) SCEM. It is demonstrated that the BF-SCEM image contrast consists of two features. One gradually changes over a wide defocus range and depends on the lateral size of the object. Another appears only near the focus and is independent of sample size. On the contrary, ADF-SCEM image contrast does not depend on the lateral size of the object. Therefore, the ADF-SCEM will provide more readily interpretable image contrast.
利用多层面法计算简单模型系统，研究了扫描共聚焦电子显微镜（SCEM）的成像特性。给出了一个简单的几何解释，特别是对明场（BF）和环形暗场（ADF）SCEM 的区别。结果表明，BF-SCEM 图像对比度由两个特征组成。一个在较宽的离焦范围内逐渐变化，取决于物体的横向尺寸。另一个仅在近焦时出现，与样品尺寸无关。相反，ADF-SCEM 图像对比度不依赖于物体的横向尺寸。因此，ADF-SCEM 将提供更易于解释的图像对比度。
