Development of grating-based super-resolution x-ray phase imaging

The spatial resolution attained by grating-based X-ray phase imaging is limited by the period of gratings to several microns. By compromising its wide field of view, it is possible to overcome the limitation by combining with an X-ray imaging microscope. In this study, we propose sub-period super-resolution X-ray phase imaging to overcome the spatial resolution limit but one that is compatible with a wide field of view. A non-self-imaging condition was adopted and a needle beam array was formed by a triangular phase grating. A sample was placed on the needle beam and scanned. The deflection of the needle beams was analyzed by an amplitude grating placed downstream with the process of the phase-stepping technique, and moiré images were recorded by an image detector located behind the amplitude grating. A super-resolution differential phase image was reconstructed for a test sample with a spatial resolution much smaller than the grating period. Although the problem of instability of the system remains, causing artifacts in the resultant image, the proof-of-concept of super-resolution X-ray phase imaging is demonstrated.