Trimodal radiography using sinusoidal phase modulating grating interferometry

Abstract

X-ray grating interferometry (XGI) provides complementary information to visualize the internal structure of an object better than conventional absorption-based imaging methods, thereby having the potential for future biomedical applications. In XGI, information retrieval is critical for qualitative and quantitative research. However, information retrieval based on the phase-stepping technique usually requires that the absolute spatial translations of these phase-stepping position series lie in the range of only a few hundred nanometers, making this technique prone to mechanical instabilities and motion artifacts. In this paper, trimodal radiography using sinusoidal phase modulating interferometry is studied. The theoretical analysis of the signal retrieval algorithm using four integrating buckets is derived, and numerical experiments are demonstrated. In the proposed method, the phase modulation is generated by shifting the grating following a sinusoidal curve while the signals are retrieved from the four frames obtained by integrating the time-varying intensity over the four quarters of the modulation period. Compared with the previously proposed method, this method is easier to implement due to relaxed requirements on the phase-shifting device; high speed and continuous data averaging will greatly promote the real applications of the X-ray grating interferometer.