Sparse phase-stepping in two-dimensional x-ray phase contrast imaging.

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.

A phase demodulation method with high spatial resolution for two-dimensional single-shot X-ray Talbot interferometry.

A new phase demodulation approach is proposed that uses windowed Fourier transforms to achieve high spatial resolution in fringe pattern analysis with a high signal-to-noise ratio for single-shot X-ray grating-based interferometry. Conventionally, Fourier transforms have been used to demodulate single-fringe patterns, but this requires a fringe pattern with a long period to obtain an acceptable signal-to-noise ratio among the demodulated parameters. However, by controlling the signal-to-noise ratio, the spatial resolution of demodulated parameters is degraded below that obtained from the phase-stepping method, which requires several images to obtain these parameters.

Two-dimensional grating-based X-ray phase-contrast imaging using Fourier transform phase retrieval.

We demonstrate a single shot two-dimensional grating-based X-ray phase-contrast imaging using a synchrotron radiation source. A checkerboard designed phase grating for π phase modulation at 17 keV and 35 keV, and a lattice-shaped amplitude grating with a high aspect ratio to shield X-rays up to 35 keV were fabricated. A Fourier analysis of Moiré fringe generated by the gratings was introduced to obtain the two-dimensional differential phase-contrast image with a single exposure.