Correction of velocity profiles on thin specimens measured by line-focus-beam acoustic microscopy

A new method of correcting apparent velocities of leaky surface acoustic waves (LSAWs), measured by line-focus-beam acoustic microscopy, for thin specimens having elastic inhomogeneities is proposed to eliminate serious errors due to back reflection. This method estimates and removes the apparent measurement errors using the frequency dependence of LSAW velocities measured at a reference position on the specimen with a certain thickness, and also using the relationship between two LSAW velocity values measured at two frequencies and apparent velocity changes included in those values. This correction method is more efficient for a number of measurement positions than the previously developed method of moving-average processing. Measurements of LSAW velocities along the crystal pulling-axis (Z-axis) direction of a Y-cut, X-axis propagating 5-mol% MgO-doped LiNbO₃ substrate, with a thickness of about 0.5 mm, are demonstrated.