Arbitrary-path fly-scan ptychography

Ptychography is a coherent diffractive imaging method that can provide a diffraction-limited, robust reconstruction of the sample's complex transmission function without the use of high-quality optics. However, the scanning nature of conventional X-ray ptychography unavoidably requires the mechanical motion of either the illumination probe or the sample. In order to avoid overhead related to breaking and acceleration for every scan position, so-called fly-scan methods were developed. Here, we present an improved variant that removes the limitation of continuous scanning along a linear scanning path and allows for ptychographic reconstruction of scans taken along an arbitrary 2D continuous trajectory. We also demonstrate numerically and experimentally that our method provides significantly improved robustness against noise, particularly for larger fly-scan steps, i.e. sample shift during an exposure, which will gain importance with the advent of 4th generation synchrotron sources, where the available coherent flux may be increased by orders of magnitude. Finally, we show that the use of a spiral scan continuous trajectory alleviates significantly raster grid artifacts.