Real time high accuracy phase contrast imaging with parallel acquisition speckle tracking*

Abstract

X-ray speckle tracking based methods can provide results with best reported angular accuracy up to 2 nrad. However, duo to the multi-frame requirement for phase retrieval and the possible instability of the x-ray beam, mechanical and background vibration, the actual accuracy will inevitably be degraded by these time-dependent fluctuations. Therefore, not only spatial position, but also temporal features of the speckle patterns need to be considered in order to maintain the superiority of the speckle-based methods. In this paper, we propose a parallel acquisition method with advantages of real time and high accuracy, which has potential applicability to dynamic samples imaging as well as on-line beam monitoring. Through simulations, we demonstrate that the proposed method can reduce the phase error caused by the fluctuations to 1% at most compared with current speckle tracking methods. Meanwhile, it can keep the accuracy deterioration within 0.03 nrad, making the high theoretical accuracy a reality. Also, we find that waveforms of the incident beam have a little impact on the phase retrieved and will not influence the actual accuracy, which relaxes the requirements for speckle-based experiments.

Research on Large Field of View Mosaic Technology Based on Surface Structured Light

“…In this study, the sinusoidal grating coding method is adopted to project the surface structured light with sinusoidal light intensity distribution onto the object surface, a four step phase shift method is used to obtain the truncated phase [5] of the image, and the three frequency heterodyne principle is used to unfold the phase of the object image.…”