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DownloadX-ray imaging techniques based on phase contrast and dark-field signals offer rich structural insights beyond conventional absorption imaging. These methods are particularly valuable in visualizing features such as soft matter interfaces, microstructural orientations, and low-density variations in materials. One promising class of techniques—single-mask or membrane-based imaging—simplifies implementation by shifting experimental complexity into digital processing. This makes them well-suited for integration into laboratory X-ray systems such as the Dark Field and Phase Contrast Imaging (DF-PCI) option developed by Xenocs.
In this method, a beam modulator (mask or membrane) is placed in the X-ray beam to produce a structured pattern on the detector. A reference image is first recorded with the membrane alone, followed by a second image after insertion of the sample (as exemplified in Figure 1). The sample locally distorts the reference pattern by attenuating, deflecting and scattering the X-rays. Several pairs of reference and sample images are acquired while shifting the membrane position. By comparing how the sample modifies the reference pattern, it becomes possible to reconstruct attenuation, phase contrast and dark-field images. For the latter, the anisotropy in the scattering signal can also be derived from the reference/sample comparison.
Figure 1. (a, d) Modulation Based imaging (MoBI) method consists in inserting a single mask into the X-ray beam to locally modulate the intensity on the detector. Several pairs of images are acquired of the mask alone (Ir) and of the mask with the sample (Is) by shifting the mask position between each acquisition pair. b) Three different modulation topologies (c) and two types of samples have been compared in this application note.
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