Incorrect support and missing center tolerances of phasing algorithms.
Incorrect support and missing center tolerances of phasing algorithms.
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DOI：
10.1364/oe.18.026441
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发表时间：
2010-12-06
期刊：
影响因子：
3.8
通讯作者：
Jacobsen C
中科院分区：
文献类型：
--
作者：
Huang X;Nelson J;Steinbrener J;Kirz J;Turner JJ;Jacobsen C
在X射线衍射显微术中，迭代算法通过使用诸如有限支撑约束的先验信息从物体的相干衍射强度中检索倒易空间相位信息和真实的空间图像。在许多实验中，物体的形状或支撑并不清楚，衍射图案也没有完全测量出来。我们在这里描述的计算机模拟，看看这两个可能的错误时，使用几种常见的重建算法的影响。过于紧密的对象支持，防止成功的收敛，但是，我们表明，这往往可以通过病理行为的相位恢复传递函数。动态范围的限制常常使得难以记录衍射图案的中心散斑。我们表明，这导致增加的文物在图像中丢失的中心散斑的数量超过约10时，从重建图像中的无约束模式的去除是有帮助的，只有当丢失的中心散斑的数量小于约50。这一模拟研究有助于判断实验记录的相干衍射图案的可重构性。
In x-ray diffraction microscopy, iterative algorithms retrieve reciprocal space phase information, and a real space image, from an object's coherent diffraction intensities through the use of a priori information such as a finite support constraint. In many experiments, the object's shape or support is not well known, and the diffraction pattern is incompletely measured. We describe here computer simulations to look at the effects of both of these possible errors when using several common reconstruction algorithms. Overly tight object supports prevent successful convergence; however, we show that this can often be recognized through pathological behavior of the phase retrieval transfer function. Dynamic range limitations often make it difficult to record the central speckles of the diffraction pattern. We show that this leads to increasing artifacts in the image when the number of missing central speckles exceeds about 10, and that the removal of unconstrained modes from the reconstructed image is helpful only when the number of missing central speckles is less than about 50. This simulation study helps in judging the reconstructability of experimentally recorded coherent diffraction patterns.