Simultaneously Determining Sensitivity and Effective Geometrical Parameters of Ultrasonic Piezoelectric Transducers Using a Self-Reciprocity Method.

Determination of the sensitivity of a transducer is essential in evaluating its central frequency and effective bandwidth, its electroacoustic conversion capability, or the measurement ability of an ultrasonic test system. In this work, a calibration method based on self-reciprocity is proposed for the determination of transducer sensitivity, which can be applied to both planar and focused transducers. The two-port electrical network of the experimental setup is analyzed, and a simplified measurement procedure is described in which the "impedance mismatch" problem is solved, and only input and output currents are needed. An acoustic transfer function is introduced, both to reduce the effects of wave energy loss on the determination of transducer sensitivity and to help extract the effective geometrical parameters of the transducer through these measured output current signals. The effects of diffraction, attenuation, and effective geometrical parameters on sensitivity determination are discussed in this work; the experimental results show that when all these factors are taken into account, accurate sensitivities for both planar and focused transducers can be obtained at various experimental distances.