We have developed a sparse phase-stepping (SPS) method for x-ray Talbot-Lau interferometry, which first constructs a SPS intensity pattern of fewer images than the conventional phase-stepping (PS) method and then fills the data gap with neighboring pixels for phase retrieval. The SPS method is highly beneficial in practice since the fundamental difference in spatial resolution between the SPS and PS methods becomes negligible due to the blur caused by an interferometer. The concept of the SPS method has been proved by the experiment using a small effective source size. Furthermore, the experiment using a large effective source size has verified that in practical situations the SPS method can reduce the required number of images for phase retrieval and still offer the retrieved images with as high a spatial resolution as the PS method.
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