Edge diffraction effect at the refraction of X rays in a diamond prism

The refraction of monochromatic X-ray radiation in an optically polished diamond prism has been studied. Measurements have been performed on the ID10 channel of the ESRF synchrotron (Grenoble). It has been found that parabolic geometric deviations of the profile of the refractive face of the prism from a plane are responsible for the interference pattern that is similar in the structure of oscillations to an edge diffraction effect. As a result, a diffraction pattern characteristic of the near-field Fresnel zone can be observed in the farfield zone. A high sensitivity to phase perturbations ensures the possibility of using this effect to analyze the parameters of an X-ray wavefront with a dimension of about 1 $\mu$m.