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Ultramicroscopy. 2012 Jul;118:35-43. doi: 10.1016/j.ultramic.2012.03.019. Epub 2012 Apr 27.
We apply monochromated illumination to improve the information transfer in focal series reconstruction to 0.5 Å at 300 kV. Contrary to single images, which can be taken arbitrarily close to Gaussian focus in a C(S)-corrected microscope, images in a focal series are taken at a certain defocus. This defocus poses limits on the spatial coherence of the illumination, and through this, limits on the brightness of the monochromated illumination. We derive an estimate for the minimum spatial coherence and the minimal brightness needed for a certain resolution at a certain defocus and apply this estimate to our focal series experiments. We find that the 0.5 Å information transfer would have been difficult and probably impossible to obtain without the exceptionally high brightness of the monochromated illumination.
我们应用单色光照明来提高焦点系列重建中的信息传递，在 300kV 时达到 0.5Å。与可以任意接近 C(S)校正显微镜中高斯焦点的单个图像不同，焦点系列中的图像是在一定的离焦下拍摄的。这种离焦限制了照明的空间相干性，从而限制了单色光的亮度。我们推导出了在一定离焦下达到一定分辨率所需的最小空间相干性和最小亮度的估计，并将该估计应用于我们的焦点系列实验。我们发现，如果没有单色光照明的异常高亮度，很难甚至不可能获得 0.5Å 的信息传递。
