Abstract
Accurate knowledge of translation positions is essential in ptychography to achieve a good image quality and the diffraction limited resolution. We propose a method to retrieve and correct position errors during the image reconstruction iterations. Sub-pixel position accuracy after refinement is shown to be achievable within several tens of iterations. Simulation and experimental results for both optical and X-ray wavelengths are given. The method improves both the quality of the retrieved object image and relaxes the position accuracy requirement while acquiring the diffraction patterns.
Highlights
Ptychography is a recent development of the lensless coherent diffraction imaging (CDI) technique that alleviates the convergence difficulty of conventional methods by recording multiple diffraction patterns of an object with overlapping illuminated regions [1,2,3]
The paper is organized as follows: section 2 details the position determination method implemented as an addition to the extended ptychographical iterative engine algorithm [14]; section 3 evaluates the performance of the algorithm in simulation; experimental results are given in section 4; discussion and conclusion are given at the end
We have proposed and demonstrated a position determination method for ptychography
Summary
Ptychography is a recent development of the lensless coherent diffraction imaging (CDI) technique that alleviates the convergence difficulty of conventional methods by recording multiple diffraction patterns of an object with overlapping illuminated regions [1,2,3]. The slow convergence of this optimization approach suggests its use being as final refinement after other algorithms have approximately determined the object and the probe function [16].The influence of position errors in ptychography has been analyzed by Hue et al in the context of electron experiments [17]. They found that an error of only a fraction of the required resolution could seriously degrade the reconstruction quality. The paper is organized as follows: section 2 details the position determination method implemented as an addition to the extended ptychographical iterative engine algorithm [14]; section 3 evaluates the performance of the algorithm in simulation; experimental results are given in section 4; discussion and conclusion are given at the end
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