Fig. 20: a) Fractional Talbot images obtained on a 2000-LPI phase grating at increasing distance with respect to the sample, corresponding to simple fractions of the Talbot distance DT = 4.68 m. b) The curves represent the normalised intensity versus the coordinate x perpendicular to the lines with a shift of 0.4 between them. = 0.69 Å (X-ray energy 18 keV) and period a = 12.7 µm.