Behan G, Cosgriff E C, Kirkland Angus I, Nellist Peter D
Department of Materials, University of Oxford, Oxford OX1 3PH, UK.
Philos Trans A Math Phys Eng Sci. 2009 Sep 28;367(1903):3825-44. doi: 10.1098/rsta.2009.0074.
The depth resolution for optical sectioning in the scanning transmission electron microscope is measured using the results of optical sectioning experiments of laterally extended objects. We show that the depth resolution depends on the numerical aperture of the objective lens as expected. We also find, however, that the depth resolution depends on the lateral extent of the object that is being imaged owing to a missing cone of information in the transfer function. We find that deconvolution methods generally have limited usefulness in this case, but that three-dimensional information can still be obtained with the aid of prior information for specific samples such as those consisting of supported nanoparticles. We go on to review how a confocal geometry may improve the depth resolution for extended objects. Finally, we present a review of recent work exploring the effect of dynamical diffraction in zone-axis-aligned crystals on the optical sectioning process.
利用横向扩展物体的光学切片实验结果，测量了扫描透射电子显微镜中光学切片的深度分辨率。我们表明，深度分辨率如预期的那样取决于物镜的数值孔径。然而，我们还发现，由于传递函数中缺少信息锥，深度分辨率取决于正在成像物体的横向范围。我们发现，在这种情况下，去卷积方法通常用处有限，但借助特定样品（如由负载型纳米颗粒组成的样品）的先验信息，仍可获得三维信息。我们接着回顾了共焦几何结构如何提高扩展物体的深度分辨率。最后，我们综述了最近探索沿晶带轴排列的晶体中的动态衍射对光学切片过程影响的工作。
