Design, fabrication and characterization of a monolithic focusing piezoceramic transducer for an anisotropic material

Piezoceramic transducers shaped as spherical caps are widely used to focus ultrasound waves in isotropic materials. For anisotropic materials, the sound wave surface is not spherical and the transducer surface should be adjusted to reproduce a portion of this wave surface to focus the emitted sound properly. In this article, we show how to design such a transducer and how to fabricate it in lab on a standard machine from a rod of raw piezo ceramic material. The main features of its electrical impedance response are well reproduced by a numerical model, allowing the identification of most of its vibrational modes. We finally measured the sound field emitted by such a transducer and found its focusing efficiency similar to that of spherical caps in isotropic media.