Long exposure time is one of the major limitations in x-ray phase-contrast imaging (XPCI). Therefore, we demonstrate a promising alternative method for grating-based XPCI coupled with cascaded Talbot–Lau interferometers (TLIs). A Fourier analysis of the moiré fringe patterns generated by the interferometers was used to obtain the multicontrast images (such as absorption, differential phase-contrast, and normalized visibility-contrast images) with a single exposure. The cascaded configuration with TLI and inverse TLI using large-period absorption gratings was established to verify the effectiveness of the algorithm and three multicontrast images of a polytetrafluoroethylene (PTFE) tube were obtained experimentally. The groove structures in the PTFE can be clearly identified in the differential phase-contrast image. This method shows potential for application of cascaded TLI in medical imaging.
Grating-based X-ray phase-contrast imaging (XPCI), have shown great potential for biological and medical imaging applications. However, the fabrication of the absorption grating, an indispensable element in conventional Talbot-Lau interferometer (TLI), making it a great challenge to this technology into practical use. In this paper, we implemented a cascade TLI (CTLI) for XPCI composed by a TLI and an inverse TLI, the self-image of TLI being used as the source of the inverse TLI, with the purpose to avoid the fabrication of small-period high aspect-ratio absorption gratings. Experiments validated the method and demonstrated the versatility and tunability of the system. The angular sensitivity as a function of the sample position was measured and discussed. Results show that the highest sensitivity is obtained, when the investigated object is close to any of two phase gratings. Furthermore, a CTLI with interference fringes being magnified to be directly detected by a common large-area detector would be established using this method. This will be useful for designing an XPCI system for applications of biomedical imaging in large field of view.