The parametric design of X-ray ptychography systems

Abstract

X-ray ptychography improves the illumination method of coherent X-ray diffraction imaging (CDI) by shifting the local illumination area to image large samples, while simultaneously improving the convergence speed and reconstruction quality of phase recovery using the constraints imposed by the overlapping of adjacent illumination areas. To improve the imaging resolution and image quality of X-ray ptychography, system parameters such as ray source parameters, illumination probe size, sample-to-detector transmission distance, detector accuracy, etc. need to be rationalized. Rationalizing the imaging system parameters is even more important when using a laboratory light source with lower brightness and coherence or when the size of the experimental field is limited. In this study, we aim to ensure the high resolution of far-field imaging and explore optimizing the system parameter settings based on a simulation method, focusing on the transmission distance between the sample and the detector. First, we design a simulation method that can flexibly adjust the system parameters to overcome the strict limitation of the matching relationship between parameters in the traditional simulation method. Second, we compare the effects of different overlap rates and up-sampling methods on the imaging results under different transmission distances so that the system can realize high quality far-field ptychography imaging under the shortest possible transmission distance. Finally, the system parameters are adjusted to compare the imaging results under different transmission distances, and the rules for setting the transmission distance under different system parameter designs are proposed.