Non-Uniform Piezoelectric Ceramic Polarisation: Minimising Ultrasound Field Diffraction

Conclusion

We have manipulated the poling process of piezoelectric ceramic discs in order to reduce the diffraction effects caused by edge waves in the acoustic field. FEM simulation was used to investigate the poling electric field format and the vibrational behaviour of apodised and non-apodised piezoelectric ceramic discs.

Apodised ceramics were used to construct ultrasound transducers and their acoustic fields showed an improved pattern when compared to those of transducers constructed with commercial ceramics poled in a conventional way. The -3dB and -6dB contours of the acoustic field show that an apodised transducer shows a large depth of field, a very desirable result if medical images are to be obtained from deep structures without lowering the ultrasound frequency.