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The performance of grating interferometers coming up now for Imaging interfaces within materials depends on the efficiency (visibility) of their main component, namely the phase grating. Therefore, experiments with monochromatic synchrotron radiation and corresponding simulations are carried out. The visibility of a Phase grating is optimized by different photon energies, varying detector to grating distances and continuous rotation of the phase grating about the grid lines. Such kind of rotation changes the projected grating shapes, and thereby the distribution profiles of phase shifts. This yields higher visibilities than derived from ideal rectangular shapes. By continuous grating rotation and variation of the propagation distance, we achieve 2D visibility maps. Such maps provide the visibility for a certain combination of grating orientation and detector position. Optimum visibilities occur at considerably smaller distances than in the standard setup.
We investigated the efficiency of phase gratings, i.e., the visibility upon variation of different parameters. Rotating around an axis parallel to the grid lines of the phase grating changes the grating’s shape and thereby the initial distribution of phase shifts. This yields high visibilities for shorter propagation distances than derived from box shapes. Tilting the grating in the scattering plane allows continuous tuning of the grating’s height that corresponds to an ideal phase shift for a particular photon energy. This opens the way for tuning the design energy suitable for the material under investigation. Our study included simulations for monochromatic sources with the sampling procedure for rectangular and triangular phase gratings.
Talbot-Lau interferometry provides X-ray imaging techniques with significant enhancement of the radiographic contrast of weakly absorbing objects. The grating based technique allows separation of absorption, refraction and small angle scattering effects. The different efficiency of rectangular and triangular shaped phase gratings at varying detector distances is investigated. The interference patterns (Talbot carpets) are modeled for parallel monochromatic radiation and measured by synchrotron radiation. In comparison to rectangular shapes of phase gratings much higher visibility is obtained for triangular shapes which yield enhanced contrast of a glass capillary test specimen.
We investigated the efficiency of phase gratings, i.e., the visibility upon variation of different parameters. Rotating around an axis parallel to the grid lines of the phase grating changes the grating’s shape and thereby the initial distribution of phase shifts. This yields high visibilities for shorter propagation distances than derived from box shapes. Tilting the grating in the scattering plane allows continuous tuning of the grating’s height that corresponds to an ideal phase shift for a particular photon energy. This opens the way for tuning the design energy suitable for the material under investigation
Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect.
At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems.
We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes.
Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries.
Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect. At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems. We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes. Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries.
The most substantial innovations in radiographic imaging techniques of the last two decades aim at enhanced image contrast of weakly absorbing micro and nano structures by taking advantage of X-ray refraction effects occurring at outer and inner surfaces. The applications range from fibre reinforced plastics to biological tissues. These techniques comprise, among others, X-ray refraction topography, diffraction enhanced imaging, phase contrast imaging, Talbot-Lau grating interferometry, and refraction enhanced imaging. They all make use of selective beam deflections up to a few minutes of arc: the X-ray refraction effect. In contrast to diffraction, this type of interaction has a 100 % scattering cross section, as shown experimentally. Since X-ray refraction is very sensitive to the orientation of interfaces, it is additionally a tool to detect, e.g., fibre or pore orientation. If the detector resolution exceeds the size of (small) individual features, one detects the integral information (of inner surfaces) within the gauge volume. We describe the above-mentioned techniques, and show their experimental implementation in the lab and at a synchrotron source. We also show strategies for data processing and quantitative analysis.
Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect.
At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems.
We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes.
Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries.