Large Step Size Fly-Scan Ptychography Using Local Sample Separation Reconstruction

Ptychography is a coherent diffractive imaging method that can achieve diffraction-limited resolution. A fly-scan mode in ptychography can mitigate time costs comparing to traditional step-scan processes. However, expanding fly-scan step size may lead to the failure of traditional phase retrieval algorithm. Here, the method we adopt differs from the multi-mode method that has become popular at X-ray synchrotrons in that it models each diffraction pattern as a sum of shifted object patches, rather than the incoherent sum of a number of modes. This methodology is extended to the standard ePIE algorithm called Multi-object ePIE (Mo-ePIE), and simulation and experimental results demonstrate its effectiveness in handling large step size fly-scan, achieving reconstructions with up to 25 maximum fly-scan pixels. Furthermore, the reintegration with multi-mode probe methods can address potential issues of system decoherence, further enhancing the quality of reconstruction. This algorithm exhibits substantial potential in accelerating ptychography experiments, offering a promising solution for high-speed applications.