Calibration of Ultrasonic Transducers by Time Deconvolution of the Diffraction Effects
Due to diffraction effects, a wavefront launched by a planar transducer becomes distorted. In the impulse domain, these effects are represented mathematically by a temporal filter. The signal observed from a transducer working in the emitting/receiving mode results from a time convolution of the diffraction filter with the acousto-electrical response of the transducer. This transducer response is not directly observable experimentally since a calibration can not be achieved without a propagation fluid. To overcome this problem, a method, based on a time-deconvolution of the radiation filter, is proposed. This method leads to an absolute calibration of the transducer impulse response and explains the results of experimental observations in a simple way. The comparisons between theory and experiment show an excellent agreement. The proposed method enables the prediction of the output signal at different observation distances. The proposed concept, applied to annular transducers, gives a simple explanation to the vibration behavior of the transducer external rings.
KeywordsImpulse Response Velocity Potential Coupling Function Diffraction Effect Radiation Coupling
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