Fig. 38: Measured evolution of the polarisation rate versus the offset of the position of the diamond crystal with respect to the Bragg angle. The dynamic theory perfectly fits the experimental data, provided a 4 arcsecond-wide convolution is used to account for the divergences (vertical and horizontal) of each monochromatic part of the polychromatic X-ray band pass Bragg reflected by the bent Si(111) crystal. The QWP is a 740 µm-thick diamond crystal set close to the (111) reflection in the Laue geometry.