Fig. 1. Dual energy X-ray grating phase contrast imaging system

Fig. 2. Distribution of fluorescence transmittance in CsI∶Tl continuous layer

Fig. 3. Relationship between the thickness of CsI and fluorescence transmittance at different energy levels

Fig. 4. Absorption coefficient of Bi at differentenergies

Fig. 5. Relationship between the thickness of Bi and the transmittance of light intensity at different energies

Fig. 6. Structure and materials of dual energy analysis grating. (a) Top view; (b) front view

Fig. 7. Imaging fringe. (a) X-ray energy is 20 keV; (b) X-ray energy is 60 keV

Fig. 8. Simulation results. (a) First order derivative imaging of the sphere phase; (b) first order derivative distribution of the sphere phase at the corresponding cross section horizontal line