Peng Yiping, Oxley Mark P, Lupini Andrew R, Chisholm Matthew F, Pennycook Stephen J
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6031, USA.
Microsc Microanal. 2008 Feb;14(1):36-47. doi: 10.1017/S1431927608080161. Epub 2008 Jan 3.
The relation between image resolution and information transfer is explored. It is shown that the existence of higher frequency transfer in the image is just a necessary but not sufficient condition for the achievement of higher resolution. Adopting a two-point resolution criterion, we suggest that a 10% contrast level between two features in an image should be used as a practical definition of resolution. In the context of scanning transmission electron microscopy, it is shown that the channeling effect does not have a direct connection with image resolution because sharp channeling peaks do not move with the scanning probe. Through a quantitative comparison between experimental image and simulation, a Fourier-space approach is proposed to estimate defocus and sample thickness. The effective atom size in Z-contrast imaging depends on the annular detector's inner angle. Therefore, an optimum angle exists for the highest resolution as a trade-off between reduced atom size and reduced signal with limited information transfer due to noise.
探讨了图像分辨率与信息传递之间的关系。结果表明，图像中高频传递的存在只是实现更高分辨率的必要但非充分条件。采用两点分辨率标准，我们建议将图像中两个特征之间10%的对比度水平用作分辨率的实际定义。在扫描透射电子显微镜的背景下，结果表明沟道效应与图像分辨率没有直接联系，因为尖锐的沟道峰不会随着扫描探针移动。通过对实验图像和模拟进行定量比较，提出了一种傅里叶空间方法来估计散焦和样品厚度。Z衬度成像中的有效原子尺寸取决于环形探测器的内角。因此，由于噪声导致信息传递有限，在减小原子尺寸和降低信号之间存在权衡，存在一个实现最高分辨率的最佳角度。
