Figure 8
Set-up for the measurement of hard X-ray wavefront distortions using a shearing interferometer consisting of two gratings and a two-dimensional detector (top). The method can be used to measure the properties of an XFEL wavefront or its optical components such as monochromators and mirrors in situ. By analyzing the distortions of the recorded Moiré patterns (bottom, left), the slope error of the reflecting surface or the wavefront can be derived with an accuracy of better than 0.1 µrad (Weitkamp et al., 2005). |