Development of an improved calibration method for the LFB ultrasonic material characterization system

Abstract

We investigated standard specimens for accurately calibrating the line-focus-beam ultrasonic material characterization (LFB-UMC) system without system dependencies. We evaluated several types of lithium tantalate (LiTaO3) substrates using two LFB-UMC systems with different device/system characteristics to measure and calibrate the propagation characteristics of the leaky surface acoustic waves (LSAWs), and analyzed the variations between the calibrated results. We concluded from this analysis that, by selecting materials with the cut surfaces and propagation directions of standard specimens that are identical to the objects to be calibrated, calibration errors resulting from different performance characteristics between the two systems could be nearly eliminated. Also, analytical errors caused by the effects of spectra with two close peaks (another propagation wave mode), one of the most common problems of characterization in the past, could be eliminated at the same time by this method.

Improvement of Velocity Measurement Accuracy of Leaky Surface Acoustic Waves for Materials with Highly Attenuated Waveform of the V(z) curve by the Line-Focus-Beam Ultrasonic Material Characterization System

“…11,22,23) The standard specimens are with their elastic constants determined by measuring the velocities of the bulk longitudinal and shear acoustic waves and the density, and a theoretical LSAW velocity (standard value) is calculated based on the calculation method described by Campbell and Jones. 24) Experimental values are obtained by measuring LSAW velocities for the standard specimens using the LFB-UMC system.…”