
Figure 1
Beam trajectories in a weakly bent crystal and schematic illustrations of interference between the beams. (a) Interference of a mirage diffraction beam (dashed curve with the corresponding refracted beam S_{1}) with another mirage diffraction beam (solid curve with the corresponding refracted beam S_{2}) to produce IFMD in a weakly bent part of the crystal. (b) Interference of a mirage diffraction beam (solid curve with the corresponding refracted beam S_{3}) with a reflected beam from the bottom surface (dashed curves with the corresponding refracted beam S_{4}) to produce IFMRB in a more weakly bent part. h is the reciprocal lattice vector and u the atomic displacement vector, and _{1}, _{2}, _{3} and _{4} are the glancing angles of the incident beam corresponding to the refracted beams S_{1}, S_{2}, S_{3} and S_{4}, respectively. 