title: A nonlinear propagation model-based phase calibration technique for membrane hydrophones.
abstract: A technique for the phase calibration of membrane hydrophones in the frequency range up to 80 MHz is described. This is achieved by comparing measurements and numerical simulation of a nonlinearly distorted test field. The field prediction is obtained using a finite-difference model that solves the nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation in the frequency domain. The measurements are made in the far field of a 3.5 MHz focusing circular transducer in which it is demonstrated that, for the high drive level used, spatial averaging effects due to the hydrophone's finite-receive area are negligible. The method provides a phase calibration of the hydrophone under test without the need for a device serving as a phase response reference, but it requires prior knowledge of the amplitude sensitivity at the fundamental frequency. The technique is demonstrated using a 50-microm thick bilaminar membrane hydrophone, for which the results obtained show functional agreement with predictions of a hydrophone response model. Further validation of the results is obtained by application of the response to the measurement of the high amplitude waveforms generated by a modern biomedical ultrasonic imaging system. It is demonstrated that full deconvolution of the calculated complex frequency response of a nonideal hydrophone results in physically realistic measurements of the transmitted waveforms.
authors.affiliation: Univ. of Southampton, ISVR (FDAG), Hampshire, UK. mc@isvr.soton.ac.uk
authors.forename: Martin P
authors.initials: MP
authors.lastname: Cooling
authors.forename: Victor F
authors.initials: VF
authors.lastname: Humphrey
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D007089:Image Enhancement / Q000295:instrumentation* / Q000592:standards*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000592:standards; D008567:Membranes, Artificial; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000295:instrumentation* / Q000592:standards*; D006113:United Kingdom; D014867:Water
chemical_list: D008567:Membranes, Artificial; D014867:Water