Abstract:
This report describes the processes of development and the performances of the transducers applied to a real-time 3-D acoustical holographic imaging system based on the encoded wavefront technique. In this system, the acoustical wave modulated its phases by a system of Walsh functions, emitted from the transducers. Thus the performance of the broad bandwidth was needed for transducers to make clear the points of the phase modulation on the waveforms. Piezorubber film was selected as a piezoelectric material and it was laminated to improve the sensitivity of the transmitters. The receivers have a copolymer film (PVDF) as the piezoelectric material. The thin film and a preamplifier mounted close to the film give superior performances to the receiver. It is made clear that the directivity of the transducers agrees with the results of theoretical analysis of the acoustic field generated by circular plane vibration; hemispherical shapes of the transducers distorted the waveform in some conditions; the broad bandwidth will be realized to set the resonance frequency lower than the operational frequency.