A design of ultrasonic transducers with curved back-electrodes

A design of ultrasonic transducers with curved back-electrodes is discussed. The theoretical principle of the design, which is based on electromagnetic theory, is quite general. A sufficient condition for producing a Gaussian beam is that the axial velocity distribution on the transducer surface is a Gaussian one. The transducer material is piezoelectric; the axial compressional oscillation is caused by the axial component of an applied electric field. The problem is that the required distribution of the electric field along the axial direction should be Gaussian. This can be achieved by using a curved dielectric back-electrode, whose shape can be determined by electromagnetic theory. The experimental results show that the sound fields generated by the Gaussian transducers fabricated based on the design agree well with the theoretical predictions