Latychevskaia Tatiana, Longchamp Jean-Nicolas, Fink Hans-Werner
Institute of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland.
Opt Express. 2011 Sep 26;19(20):19330-9. doi: 10.1364/OE.19.019330.
Coherent diffraction imaging (CDI) for visualizing objects at atomic resolution has been realized as a promising tool for imaging single molecules. Drawbacks of CDI are associated with the difficulty of the numerical phase retrieval from experimental diffraction patterns; a fact which stimulated search for better numerical methods and alternative experimental techniques. Common phase retrieval methods are based on iterative procedures which propagate the complex-valued wave between object and detector plane. Constraints in both, the object and the detector plane are applied. While the constraint in the detector plane employed in most phase retrieval methods requires the amplitude of the complex wave to be equal to the squared root of the measured intensity, we propose a novel Fourier-domain constraint, based on an analogy to holography. Our method allows achieving a low-resolution reconstruction already in the first step followed by a high-resolution reconstruction after further steps. In comparison to conventional schemes this Fourier-domain constraint results in a fast and reliable convergence of the iterative reconstruction process.
用于以原子分辨率可视化物体的相干衍射成像（CDI）已成为一种很有前景的单分子成像工具。CDI的缺点与从实验衍射图案进行数值相位恢复的困难有关；这一事实促使人们寻找更好的数值方法和替代实验技术。常见的相位恢复方法基于迭代过程，该过程在物体平面和探测器平面之间传播复值波。在物体平面和探测器平面上都应用了约束条件。虽然大多数相位恢复方法中在探测器平面上采用的约束要求复波的幅度等于测量强度的平方根，但我们基于与全息术的类比提出了一种新颖的傅里叶域约束。我们的方法允许在第一步就实现低分辨率重建，然后在后续步骤中实现高分辨率重建。与传统方案相比，这种傅里叶域约束导致迭代重建过程快速且可靠地收敛。
