Principle :
The device extracts the bubble population from acoustical measurements made at several frequencies. It consists of a set of two transducers/hydrophones connected to a computer. A data acquisition board controls the hydrophones' signal generation and acquisition. The PC is also used for analysis of the data and provides, using DYNAFLOW's software, the sound speed and attenuation as a function of frequency.

The bubble population can be obtained from these measurements by a solution of two Fredholm Integral Equations of the first kind. These equations are ill-posed and are a challenge to solve - especially when the data has noise. In our research, we developed novel algorithms that are able to accurately solve these equations using a constrained optimization technique.

The instrument can provide the data in near real time, thus making it suitable for process applications. The bubble distributions from the ABS have been validated by comparison with micro-photography.