Estimation of ultrasonic source distributions of electroacoustic transducers

In this paper, a modelling and identification approach is proposed for the estimation of the source distribution of an electroacoustic transducer. The ultrasonic source and field are modelled by the superposition of Gaussian beams. The model order, i.e. the number of the Gaussian beams used, and the characteristic coefficients of these Gaussian beams for the superposition depend on the source distribution. An experimental system is built to measure the acoustic fields. From the measured amplitude and phase data, a maximum likelihood (ML) estimator is utilized to determine the order and characteristic coefficients of the field model. Once the order and coefficients of the field model are estimated, a complete parametric description of the source distribution is then obtained. Using the estimated source distribution, the prediction of the acoustic fields can be made. The predicted and measured fields are then compared to validate the model. The experimental results demonstrate the reliability of the technique.