Venkatakrishnan S V, Drummy L F, Jackson M A, Bouman C A, Simmons J P, De Graef M
Purdue University, West Lafayette, IN 47907, USA.
Air Force Research Laboratory, Wright Patterson AFB, OH 45433, USA.
Ultramicroscopy. 2016 Jan;160:7-17. doi: 10.1016/j.ultramic.2015.09.008. Epub 2015 Sep 21.
We introduce a forward model for the computation of high angle annular dark field (HAADF) images of nano-crystalline spherical particles and apply it to image simulations for assemblies of nano-spheres of Al, Cu, and Au with a range of sizes, as well as an artificial bi-sphere, consisting of solid hemispheres of Al and Cu or Al and Au. Comparison of computed intensity profiles with experimental observations on Al spheres at different microscope accelerating voltages provides confidence in the forward model. Simulated tomographic tilt series for both HAADF and bright field (BF) images are then used to illustrate that the model-based iterative reconstruction (MBIR) approach is capable of reconstructing sphere configurations of mixed atomic number, with the correct relative reconstructed intensity ratio proportional to the square of the atomic number ratio.
我们引入了一种正向模型，用于计算纳米晶球形颗粒的高角度环形暗场（HAADF）图像，并将其应用于不同尺寸的铝、铜和金纳米球组件以及由铝和铜或铝和金的实心半球组成的人工双球的图像模拟。将计算得到的强度分布与不同显微镜加速电压下铝球的实验观测结果进行比较，为正向模型提供了可信度。然后，利用HAADF和明场（BF）图像的模拟断层倾斜序列来说明基于模型的迭代重建（MBIR）方法能够重建混合原子序数的球配置，且重建强度的相对正确比值与原子序数比的平方成正比。
