Differential Phase Contrast and Dark-Field ImagingGrating interferometry based hard X-ray phase contrast can provide superior contrast, especially in soft tissue, when compared to conventional attenuation based imaging. At the same time, grating interferometry also provides a dark-field image that can show details both in biomedial and material science applications.
In recent experiments at synchrotron sources, we have shown two ways of recording the full differential phase gradient vector. One approach, using tilted gratings works well in tomography using one-dimensional line grating structures and can lead to improved tomographic reconstructions  as shown for a saggital slice through a rat brain in Figure 1.
The other approach to record the full phase gradient vector is based on two-dimensional grating structures that can be fabricated using deep reactive ion etching. This approach is well suited to radiography and can provide a differential phase signal in two directions, as well as a directional dark-field signal [8,9,7]. An example of such a directional scattering image of an ant is shown in Figure 2. This method also has interesting applications in in-situ X-ray optics metrology.
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