Two-step phase retrieval method with unknown phase shift on non-absorbtion grating X-ray differential phase contrast imaging system

Conventional phase retrieval methods for X-ray differential phase-contrast imaging are carried out with at least three interferograms. In this contribution, we present a novel two-step phase-shifting algorithm with an arbitrary unknown phase shift between 0 and π . Based on the detecting model of a grating interferometer, the unknown phase shifts are extracted by a noniterative algorithm. Then the phase distribution of the detected sample can be further obtained from the retrieval phase shift. This method is experimentally validated based on non-absorbtion grating imaging system and the result verified its effectiveness.