Stroboscopic x-ray topography in crystals under 10-μm-surface acoustic wave excitation

Abstract

High-frequency stroboscopic x-ray topography is developed with the goal to visualize surface acoustic wave propagation. For this purpose the resonant frequencies of LiNbO3-based surface acoustic wave devices (290 and 355 MHz) are synchronized with the frequency of x-ray flashes (5.68 MHz) delivered by the European Synchrotron Radiation Facility (ESRF, Grenoble). X-ray topographs, taken in such a manner, revealed periodic contrast caused by a “frozen” acoustic deformation field. This technique allows for visualization of individual wavefronts of traveling acoustic waves having a wavelength in a 10 μm range. X-ray stroboscopic topographs showed a weak wavefront distortion due to the scattering of acoustic waves on linear dislocations. Secondary spherical waves were observed as a result of the strong acoustic wave interaction with submicron size density perturbations.