A Novel Method to Measure Acoustic Power of Focusing Transducer with Spherical Surface Based on Self-Reciprocity Theorem

A novel method to measure acoustic power of focusing transducer based on the self-reciprocity theorem of convergent spherical acoustic wave is proposed. The performance of this reciprocity method is compared with that of the radiation force balance (RFB) method and the admittance circle method. The average deviations of the reciprocity method from RFB in measurements of the acoustic power and the radiation conductance for a focusing transducer of 1.525MHz are 7.5% and 3.6% respectively, and for another focusing transducer of 5.27MHz, they are 1.7% and 1.1%. The measured radiation conductance deviation by the reciprocity method from the admittance circle method for the focusing transducer of 1.525MHz is 7.9%. It presents encouraging results even in measuring low acoustic power level. The overall uncertainty of acoustic power measurement using the method is evaluated below 10%, and it has many advantages such as high signal-to-noise ratio, good stability and less interference of bubbles and environment.