A study on the dispersion relations of Lamb waves propagating along LiNbO₃ plate with a laser ultrasound technique

A noncontact laser ultrasound technique is applied for the measurement of multi-mode dispersion relations of Lamb waves propagating in an LiNbO₃ plate with different propagating directions. Also, a theoretical treatment based on a partial wave analysis is provided for the calculations of dispersion relations. For all the propagation angles, the measured dispersion curves show good agreement with the theoretical calculations. The Rayleigh wave speeds are extracted from the measured and calculated dispersion curves, showing favorable agreement with classical theory by Campbell.