Experimental Study of X-ray Phase Contrast Imaging Based on Cascaded Grating

A cascade interferometer for X-ray phase-contrast imaging composed by a Talbot-Lau interferometer and an inverse Talbot-Lau interferometer was implemented, which the self-image of Talbot-Lau interferometer being used as the source of the inverse Talbot-Lau interferometer, with the purpose to avoid the fabrication of small-period high aspect-ratio absorption gratings. Experiments validated the method, while moire fringes and intensity oscillation curves of the imaging system are obtained. The maximum visibility of the fringes was 17.4%. With the absorption grating deviating from the zero position, the visibility of the fringes decreased gradually. But it remained above 10, when the position of the absorption grating spaned from - 17 mm to 12 mm. And the angular sensitivity as a function of the sample position was discussed. Results show that the highest sensitivity is obtained, when the investigated object is close to the phase grating. This will be useful for designing an X-ray phase-contrast imaging system for applications of biomedical imaging in large field of view.