Department of Physics and Institute for Medical Engineering, Technische Universität München, 85748 Garching, Germany.
Sci Rep. 2013;3:1927. doi: 10.1038/srep01927.
Inline holography is a common phase-contrast imaging method which uses free-space propagation to encode the phase signal into measured intensities. However, quantitative retrieval of the sample's image remains challenging, imposing constraints on the nature of the sample or on the propagation distance. Here, we present a way of simultaneously retrieving the sample's complex-valued transmission function and the incident illumination function from near-field diffraction patterns. The procedure relies on the measurement diversity created by lateral translations of the sample with respect to a structured illumination. The reconstruction approach, in essence identical to that employed in ptychography, is applied to hard X-ray synchrotron measurements and to simulations. Compared to other inline holography techniques, we expect near-field ptychography to reduce reconstruction artefacts by factoring out wavefront imperfections and relaxing constraints on the sample's scattering properties, thus ultimately improving the robustness of propagation-based X-ray phase tomography.
共线全息术是一种常见的相位衬度成像方法，它利用自由空间传播将相位信号编码到测量强度中。然而，对样品图像的定量恢复仍然具有挑战性，这对样品的性质或传播距离施加了限制。在这里，我们提出了一种从近场衍射图案中同时恢复样品的复透射函数和入射照明函数的方法。该过程依赖于相对于结构照明进行样品横向平移所产生的测量多样性。重建方法实质上与相衬术中使用的方法相同，已应用于硬 X 射线同步加速器测量和模拟中。与其他共线全息术技术相比，我们预计近场相衬术通过消除波前不完美并放宽对样品散射特性的限制，从而最终提高基于传播的 X 射线相层析成像的稳健性，来减少重建伪影。
