title: Investigation of the partially coherent effects in a 2D Talbot interferometer.
abstract: The recent use of a one-dimensional (1D) X-ray Talbot interferometer has triggered great interest in X-ray differential phase contrast imaging. As an improved version of a 1D interferometer, the development of two-dimensional (2D) grating interferometry strongly stimulated applications of grating-based imaging. In the framework of Fresnel diffraction theory, we investigated the self-image of 2D-phase gratings under partially coherent illumination. The fringe visibility of the self-image has been analyzed as a function of the spatial coherence length. From the viewpoint of self-image visibility, it is possible to find the optimal 2D grid for 2D X-ray grating interferometer imaging. Numerical simulations have been also carried out for quantitative evaluation. Results, in good agreement with theoretical analysis, indicate the spatial coherence requirements of the radiation illuminating a 2D grating interferometer. Moreover, our results can be used to optimize performances of a 2D grating interferometer and for further theoretical and experimental research on grating-based imaging systems.
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Ge
authors.forename: Zhili
authors.initials: Z
authors.lastname: Wang
authors.forename: Kun
authors.initials: K
authors.lastname: Gao
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Youli
authors.initials: Y
authors.lastname: Hong
authors.forename: Dajiang
authors.initials: D
authors.lastname: Wang
authors.forename: Zhongzhu
authors.initials: Z
authors.lastname: Zhu
authors.forename: Peiping
authors.initials: P
authors.lastname: Zhu
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Wu