Philippsen Ansgar, Engel Hans-Andreas, Engel Andreas
Maurice E. Müller Institute for Structural Biology, University of Basel, Klingelbergstr. 70, 4056 Basel, Switzerland.
Ultramicroscopy. 2007 Feb-Mar;107(2-3):202-12. doi: 10.1016/j.ultramic.2006.07.010. Epub 2006 Aug 24.
A theoretical description of the contrast-imaging function is derived for tilted specimens that exhibit weak-phase object characteristics. We show that the tilted contrast-imaging function (TCIF) is a linear transformation, which can be approximated by the convolution operation for small tilt angles or for small specimens. This approximation is not valid for electron tomography, where specimen tilts are above 60 degrees and specimen dimensions amount to some 10 microm. The approximation also breaks down for electron crystallography, where atomic resolution is to be achieved. Therefore, we do not make this approximation and propose a generalized algorithm for inverting the TCIF. The implications of our description are discussed in the context of electron tomography, single particle analysis, and electron crystallography, and the improved resolution is quantitatively demonstrated.
针对呈现弱相位物体特征的倾斜样品，推导了对比度成像函数的理论描述。我们表明，倾斜对比度成像函数（TCIF）是一种线性变换，对于小倾斜角或小尺寸样品，它可以通过卷积运算来近似。这种近似对于电子断层扫描是无效的，在电子断层扫描中样品倾斜角度大于60度且样品尺寸约为10微米。在要实现原子分辨率的电子晶体学中，这种近似也不成立。因此，我们不做这种近似，并提出了一种用于反转TCIF的广义算法。我们在电子断层扫描、单颗粒分析和电子晶体学的背景下讨论了我们描述的意义，并定量展示了分辨率的提高。
