“…The sources, which have been used to adequately build the transducer's structure and replicate its dynamics in FE model, were the technical notes about the ultrasonic principles important to wedge transducer application and design, including the scheme and main requirements to the active element, backing, matching layers and the sound path presented by Olympus Co. ® [48], the outer dimensions of the used actuator (see Figure 3), the frequency response functions for the electric current through PZT active plate, and out-of-plane displacement amplitude on the actuator's footprint (see Figure 4a,b), which have been determined experimentally. Only averaged normal displacement amplitudes of the actuator's contact surface were measured experimentally by using the VibroGo single-point vibrometer (Polytec Co. ® , Irvin, Figures 1b and 2b demonstrates that the wavelength of A0 Lamb waves mode is 2-5 time less than the wavelength of SS0 horizontally polarized shear wave, i.e., spatial defects resolution of A0 waves can be significantly better that is fully consistent with the results of the papers [11,20,22,30].…”