Bi-angular lens for material characterization

In this paper a new lens design is proposed for the characterization of layered materials. A Lamb wave lens employs Lamb waves for this purpose since these waves propagate along interfaces. However, below a cut-off angle, the critical angles of Lamb wave modes are low and the generated V(z) curves have a small number of oscillations, which in turn causes measurement difficulties and accuracy degradation. The bi-angular lens described in this paper, generates an extraobliquely incident wave, instead of a normally incident beam, in order to provide the reference specular reflection. Simulation results as well as experimental results are presented and it is shown that a high sensitivity can be obtained by using this new lens