Lamb Wave Tomography Using Laser-Based Ultrasonics

Lamb waves are widely used for the nondestructive evaluation of plate structures. By using Lamb wave attenuation, velocity and mode conversion, information about the sizes and positions of existing defects can be obtained. Lamb waves have also been used for C-scan imaging of plates. In C-scan imaging, the measurement has to be performed at each point on the sample to characterize the material at that point. Recently, computed tomography techniques using Lamb waves and surface acoustic waves have been proposed and investigated [1–3]. The computed tomographic technique provides faster image reconstruction and the ability to image an area from outside the area. This is often desired when the defected area is not directly accessible