Department of Materials, University of Oxford, Oxford, U.K.
J Microsc. 2011 Nov;244(2):170-80. doi: 10.1111/j.1365-2818.2011.03522.x. Epub 2011 Aug 4.
Atom probe tomography is an accurate analytical and imaging technique which can reconstruct the complex structure and composition of a specimen in three dimensions. Despite providing locally high spatial resolution, atom probe tomography suffers from global distortions due to a complex projection function between the specimen and detector which is different for each experiment and can change during a single run. To aid characterization of this projection function, this work demonstrates a method for the reverse projection of ions from an arbitrary projection surface in 3D space back to an atom probe tomography specimen surface. Experimental data from transmission electron microscopy tilt tomography are combined with point cloud surface reconstruction algorithms and finite element modelling to generate a mapping back to the original tip surface in a physically and experimentally motivated manner. As a case study, aluminium tips are imaged using transmission electron microscopy before and after atom probe tomography, and the specimen profiles used as input in surface reconstruction methods. This reconstruction method is a general procedure that can be used to generate mappings between a selected surface and a known tip shape using numerical solutions to the electrostatic equation, with quantitative solutions to the projection problem readily achievable in tens of minutes on a contemporary workstation.
原子探针层析技术是一种精确的分析和成像技术，能够重建样品在三维空间中的复杂结构和组成。尽管原子探针层析技术具有局部高空间分辨率，但由于样品和探测器之间的复杂投影函数不同，每个实验都有不同的投影函数，并且在单个运行过程中可能会发生变化，因此会产生全局变形。为了帮助描述这种投影函数，这项工作展示了一种将来自任意三维空间投影面的离子反向投影回原子探针层析样品表面的方法。将透射电子显微镜倾斜层析的实验数据与点云表面重建算法和有限元建模相结合，以物理和实验驱动的方式生成与原始尖端表面的映射。作为一个案例研究，在进行原子探针层析之前和之后使用透射电子显微镜对铝尖端进行成像，并将样品轮廓用作表面重建方法的输入。这种重建方法是一种通用程序，可以使用静电方程的数值解在选定的表面和已知的尖端形状之间生成映射，在当代工作站上，投影问题的定量解可以在几十分钟内轻松获得。
