A method to determine the focal peak sound pressure of the high intensity focused ultrasound field was proposed.Under low amplitude linear propagation conditions,linear pressure waveforms were measured and modeled in water a focused transducer with nominal aperture of 60mm and focal length of 75mm.The corrected parameters input to a Westervelt numerical model were determined based on experimental low amplitude beam plots.The simulated nonlinear waveforms at the focus were obtained,which were distorted strongly with a discrepancy between the peak compressional and rarefactional pressures.The first three harmonics were extracted from the distorted wave by a zero-phase band-pass filter,showing that the relative phases almost keep constant as the source pressure increases.Measurements were performed with a fiber optic probe hydrophone as the focused transducer driving with high-energy.Combined the measured pressure amplitudes with simulated phases of first three harmonics,the peak sound pressure at the focus was obtained.For this focused transducer driving in 250 Vp-p,its peak compressional pressure is 7.56 MPa,and rarefactional pressure is 4.98 MPa.
万方数据
