Ultrasonic diffraction along axes of two-fold symmetry

Agreement has been achieved between ultrasonic diffraction losses as measured and calculated for twofold symmetry axes. Measurements were made by the pulse-echo method with essentially monochromatic RF bursts and X-cut quartz transducers on [110] Si, Ge, and NaCl. Calculations were made using the Thompson-Newberry (T-N) measurement model which expresses the wavefield of the transducer as a Gauss-Hermite series and expands the slowness surface of the anisotropic medium in terms up through quadratic with azimuthal variability. In this formulation the [110] direction is a saddle point. The measurement model was checked against previous experimental and theoretical work and was found to reproduce the earlier results exactly. In principle, the T-N measurement model can handle diffraction losses in arbitrary directions.<>