Publicatie: Visibility retrieval and spatial dark-field resolution in DP-XGI

There has been a rising interest in multi-scale imaging of materials and structures. However, conventional X-ray-based imaging methods are fundamentally limited by the discretization of the image, causing a direct coupling between pixel size and field of view. Through small-angle scattering, X-ray dark-field (DF) imaging is sensitive to the sub-pixel structure of the sample being imaged, overcoming this limitation. In grating-based dark-field imaging, the DF signal is operationally defined as the relative change in visibility of the interference pattern in each pixel, which is commonly probed via the process called phase stepping. We show through simulations that the real-space DF resolution in dual-phase X-ray grating interferometry (DP-XGI), for which the interference pattern is directly resolvable, is limited by the fringe period, being larger than the pixel size. We therefore propose a single-shot visibility retrieval algorithm for DP-XGI, which does not require precise phase stepping and is by design restricted to the real-space resolution given by the fringe period. The simulation demonstrates that minimal physical information is lost with a single shot. It is argued that phase-stepping in DP-XGI has only limited benefit compared to single-shot, while it comes at the cost of more complex measurement.

Sinnaeve et al, Vol. 34, No. 18 / 7 Sep 2026 / Optics Express 33622