A vibrating monochromator for the 'diffraction topography' beamline of the ESRF

A perfect silicon crystal is used at the ESRF as monochromator for monochromatic synchrotron diffraction topography. This monochromator produces a beam with a narrow range of energy, which is not suitable for some experiments. Moreover, the diffracted energy varies spatially on the monochromatic beam section. A solution to overcome the narrow energy range and the wavelength dispersion is the use of a vibrating monochromator. We present in this paper the three-pole electromagnet device used to vibrate, at about 100 Hz, the perfect (110) Si crystal, the results on the homogeneity of the vibrations and the X-ray topographs recorded using this method.