X-ray imaging directly visualizes differing densities, and therefore refractive indices, of materials within a sample. As a result, the wavefield at the exit surface of the object contains encoded information regarding that object. X-rays are attenuated, scattered, and refracted when traversing a material. 1 Their ability to pass through matter makes x-rays highly useful in a broad range of applications, particularly in medical imaging. X-rays have been utilized in a variety of applications since their discovery by Röntgen. The obtained DF reconstructions have an image quality comparable to alternative x-ray DF techniques. The DF tomographic reconstructions of the wood sample provided complementary, and otherwise inaccessible, information to augment the phase contrast reconstructions, which were also computed.Ĭonclusions: An intrinsic speckle tracking approach to speckle-based imaging can tomographically reconstruct an object’s DF signal at a low sample exposure and with a simple experimental setup. DF tomography was performed using a filtered back projection reconstruction algorithm. Results: Effective DF projection images, as well as the DF tomographic reconstructions of the wood sample, are presented. The associated inverse problem of extracting the effective DF signal was numerically stabilized using a “weighted determinants” approach. Here, we assumed that (a) small-angle scattering fans at the exit surface of the sample are rotationally symmetric and (b) the object has both attenuating and refractive properties.
Purpose: We investigate how an intrinsic speckle tracking approach to speckle-based x-ray imaging is used to extract an object’s effective dark-field (DF) signal, which is capable of providing object information in three dimensions.Īpproach: The effective DF signal was extracted using a Fokker–Planck type formalism, which models the deformations of illuminating reference beam speckles due to both coherent and diffusive scatter from the sample.