The temporal coherence of the synchrotron X-ray source is exploited to reinforce the contrast of 2D images of poorly absorbing materials or when the difference in density between two components is weak. The effect of the “phasing  contrast” is even more important when the detector is placed further away from the sample.

A recombination algorithm calculates, using projections obtained from different distances, the 2D map of the refraction index of the sample, relative to its density.
The 3D reconstruction is then carried out as per the standard X-ray microtomography absorption process.