  Recently, X-ray interferometers with more than one phase grating have been
developed for differential phase contrast (DPC) imaging. In this study, a novel
framework is developed to predict such interferometers' angular sensitivity
responses (the minimum detectable refraction angle). Experiments are performed
on the dual and triple phase grating interferometers, separately. Measurements
show strong consistency with the predicted sensitivity values. Using this new
approach, the DPC imaging performance of X-ray interferometers with multiple
phase gratings can be further optimized for future biomedical applications.
