Gamma ray focussing is a central topic in the X- and gamma-ray astronomy and in medical imaging. A great advance in sensitivity and resolution can be obtained by focusing systems based on Laue lenses obtained by assembling a large number of single crystals in the Laue diffraction configuration.Self-standing bent crystals obtained by a method based on the surface damaging may permit to enhance the diffraction efficiency and to obtain a spontaneous and permanent lattice curvature, fundamental when assembling a large number of crystals. To date the only measurements of diffraction efficiency in these crystals were obtained at low x-ray energies showing an unexpected high value of the integrated intensity. For gamma ray focussing it is important to measure the diffraction profiles of surface damaged bent crystals at high gamma ray energies and to confirm that the presence of a few micron thick heavily damaged layer has minor effects on the diffraction efficiency. The aim of the present proposal is the measurement of diffraction profiles of curved GaAs, Si and Ge crystals, produced by the method of surface damage, at high x-ray energies (184, 517 and 788 keV) for lattice planes