Haigh S J, Sawada H, Kirkland Angus I
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
Philos Trans A Math Phys Eng Sci. 2009 Sep 28;367(1903):3755-71. doi: 10.1098/rsta.2009.0124.
Transmission electron microscope (TEM) images recorded under tilted illumination conditions transfer higher spatial frequencies than axial images. This super resolution information transfer is highly directional in a single image, but can be extended in all directions through the use of complementary beam tilts during exit wave function reconstruction. We have determined the optimal experimental tilt magnitude for aperture synthesis in an aberration-corrected TEM. It is shown that electron-optical aberration correction allows the use of larger tilt angles and reduces the constraints that are imposed on experimental data acquisition in an uncorrected microscope. We demonstrate that, in many cases, the resolution improvement achievable is now limited by the sample and not by instrumental parameters. An exit wave function is presented that has been successfully reconstructed from a dataset of aberration-corrected images, including images acquired at a beam tilt of 18 mrad, which clearly demonstrates a resolution improvement from 0.11 nm to better than 0.08 nm at 200 kV.
在倾斜照明条件下记录的透射电子显微镜（TEM）图像比轴向图像传递更高的空间频率。这种超分辨率信息传递在单个图像中具有高度方向性，但可以通过在出射波函数重建过程中使用互补光束倾斜在所有方向上扩展。我们已经确定了像差校正TEM中孔径合成的最佳实验倾斜幅度。结果表明，电子光学像差校正允许使用更大的倾斜角度，并减少了未校正显微镜对实验数据采集所施加的限制。我们证明，在许多情况下，现在可实现的分辨率提高受样品限制而非仪器参数限制。给出了一个从像差校正图像数据集成功重建的出射波函数，其中包括在18毫弧度的光束倾斜下采集的图像，这清楚地表明在200 kV时分辨率从0.11纳米提高到了优于0.08纳米。
