Focusing nondiffracting BAW transducer

We present a detailed scheme for piezoelectric interdigital-type transducer on quartz that would generate a localized nondiffracting beam within the depth of a crystal. The transducer is analogous with optical diffractive elements but the presence of anisotropy and several acoustic modes complicates the design, and numerical modeling is required for the final optimization of the local transducer structure. The transducer proposed is suited for focusing the acoustic wave energy within a small volume inside the crystal at the depth of 500 μm below the surface. For a water of that same thickness, the produced wave pattern may be verified on the opposite surface of the wafer.