Blykers Benjamin K, Organista Caori, Boone Matthieu N, Kagias Matias, Marone Federica, Stampanoni Marco, Bultreys Tom, Cnudde Veerle, Aelterman Jan
Pore-Scale Processes in Geomaterials Research Group (PProGRess), Department of Geology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.
Ghent University Centre for X-Ray Tomography (UGCT), Proeftuinstraat 86/N12, 9000, Ghent, Belgium.
Sci Rep. 2021 Sep 16;11(1):18446. doi: 10.1038/s41598-021-97915-y.
X-ray computed micro-tomography typically involves a trade-off between sample size and resolution, complicating the study at a micrometer scale of representative volumes of materials with broad feature size distributions (e.g. natural stones). X-ray dark-field tomography exploits scattering to probe sub-resolution features, promising to overcome this trade-off. In this work, we present a quantification method for sub-resolution feature sizes using dark-field tomograms obtained by tuning the autocorrelation length of a Talbot grating interferometer. Alumina particles with different nominal pore sizes (50 nm and 150 nm) were mixed and imaged at the TOMCAT beamline of the SLS synchrotron (PSI) at eighteen correlation lengths, covering the pore size range. The different particles cannot be distinguished by traditional absorption µCT due to their very similar density and the pores being unresolved at typical image resolutions. Nevertheless, by exploiting the scattering behavior of the samples, the proposed analysis method allowed to quantify the nominal pore sizes of individual particles. The robustness of this quantification was proven by reproducing the experiment with solid samples of alumina, and alumina particles that were kept separated. Our findings demonstrate the possibility to calibrate dark-field image analysis to quantify sub-resolution feature sizes, allowing multi-scale analyses of heterogeneous materials without subsampling.
X射线计算机显微断层扫描通常需要在样品大小和分辨率之间进行权衡，这使得对具有广泛特征尺寸分布的材料（如天然石材）的代表性体积进行微米级研究变得复杂。X射线暗场断层扫描利用散射来探测亚分辨率特征，有望克服这种权衡。在这项工作中，我们提出了一种使用通过调整塔尔博特光栅干涉仪的自相关长度获得的暗场断层图像来量化亚分辨率特征尺寸的方法。将具有不同标称孔径（50纳米和150纳米）的氧化铝颗粒混合，并在瑞士光源（保罗谢勒研究所）的TOMCAT光束线处以18个相关长度进行成像，覆盖孔径范围。由于不同颗粒的密度非常相似，且在典型图像分辨率下孔隙无法分辨，因此传统的吸收式μCT无法区分它们。然而，通过利用样品的散射行为，所提出的分析方法能够量化单个颗粒的标称孔径。通过对氧化铝固体样品和分离保存的氧化铝颗粒进行实验重现，证明了这种量化方法的稳健性。我们的研究结果表明，有可能校准暗场图像分析以量化亚分辨率特征尺寸，从而在不进行二次采样的情况下对异质材料进行多尺度分析。
