Fourier-transform Ghost Imaging with Hard X-rays (1603.04388v2)

Abstract: Knowledge gained through X-ray crystallography fostered structural determination of materials and greatly facilitated the development of modern science and technology in the past century. Atomic details of sample structures is achievable by X-ray crystallography, however, it is only applied to crystalline structures. Imaging techniques based on X-ray coherent diffraction or zone plates are capable of resolving the internal structure of non-crystalline materials at nanoscales, but it is still a challenge to achieve atomic resolution. Here we demonstrate a novel lensless Fourier-transform ghost imaging method with pseudo-thermal hard X-rays by measuring the second-order intensity correlation function of the light. We show that high resolution Fourier-transform diffraction pattern of a complex amplitude sample can be achieved at Fresnel region and the amplitude and phase distributions of a sample in spatial domain can be retrieved successfully. The method of lensless X-ray Fourier-transform ghost imaging extends X-ray crystallography to non-crystalline samples, and its spatial resolution is limited only by the wavelength of the X-ray, thus atomic resolution should be routinely obtainable. Since highly coherent X-ray source is not required, comparing to conventional X-ray coherent diffraction imaging, the method can be implemented with laboratory X-ray sources, and it also provides a potential solution for lensless diffraction imaging with fermions, such as neutron and electron where the intensive coherent source usually is not available.

• The paper demonstrates a novel lensless ghost imaging technique that extends X-ray diffraction methods to non-crystalline samples.
• The method exploits pseudo-thermal hard X-rays and records second-order intensity correlations to reconstruct amplitude and phase distributions.
• The approach suggests potential for atomic resolution without high-coherence sources, enabling accessible, lab-scale imaging setups.

Fourier-transform Ghost Imaging with Hard X-rays in Non-crystalline Samples

The paper presents a novel approach to extending X-ray imaging techniques through Fourier-transform Ghost Imaging (FGI) using pseudo-thermal hard X-rays. While X-ray crystallography has been effective in resolving atomic structures of crystalline materials, it falls short in non-crystalline samples. This research contributes to overcoming this limitation by providing a lensless imaging technique that potentially achieves atomic resolution without requiring highly coherent X-ray sources.

The core innovation in this paper is the use of FGI with a pseudo-thermal X-ray source. The technique involves capturing high-resolution Fourier-transform diffraction patterns by recording second-order intensity correlations. The experiment shows that such a method can successfully retrieve both amplitude and phase distributions of complex samples in the spatial domain. The spatial resolution achievable through this method is only constrained by the X-ray wavelength, suggesting that atomic resolution could be routinely attainable.

Methodology

The authors employed a unique experimental setup at the Shanghai Synchrotron Radiation Facility. A pseudo-thermal X-ray source was used to generate spatially incoherent X-ray beams, which then illuminated the test sample. Without the customary need for a beam splitter—because perfect beam splitters are unavailable for hard X-rays—the researchers devised a protocol where a panel detector records sequential intensity distributions with and without the sample in place. These data pairs are used to derive the Fourier-transform diffraction pattern of the sample, enabling the subsequent reconstruction of the real-space image.

A notable aspect of the method is that it does not rely on high-coherence X-ray sources, thus opening new avenues for laboratory-scale setups. The possibilities extend to imaging with other fermions, such as neutrons and electrons, which traditionally face challenges due to the lack of coherent source availability. This implicates potential advancements in material sciences and biomedical imaging by offering alternative routes for high-resolution analysis.

Results and Implications

The paper demonstrates successfully obtaining the Fourier-transform diffraction pattern and reconstructing the spatial amplitude and phase distribution of a non-crystalline sample. With the experimental results aligning well with theoretical predictions, the authors confirmed the effectiveness of their technique. The spatial resolution achieved demonstrates the ability of FGI to extend X-ray crystallography methods beyond their typical constraints.

The implications of this work are significant both practically and theoretically. Practically, the research suggests a pathway to more accessible high-resolution imaging techniques that can be adopted across various laboratory environments. Theoretically, it opens further exploration of lensless imaging methods across different particle types, likely affecting future computational imaging and potentially enhancing other scientific fields such as materials science and biological investigations.

Future Directions

The research sets the stage for numerous future endeavors. Among the most promising directions is the refinement of the FGI technique to support real-time imaging applications and further expanding it to other spectral regimes. Additionally, the theoretical groundwork laid herein encourages the exploration of ghost imaging in other novel contexts, possibly integrating machine learning algorithms to optimize data reconstruction from intensity correlations.

Continued improvements and cross-disciplinary endeavors may broaden the adoption and enhance the precision of such imaging techniques, making them indispensable tools in scientific investigations requiring non-invasive, high-resolution imaging capabilities.