Improvements in the synthesis of highly focused ultrasonic beams using the negative-time part of the 0-order X-wave driving signals

Luis Castellanos, Antonio Ramos, Héctor Calás, and Ivonne Bazán
Jap. Journal of Applied Physics, nº 54, paper 057003, 2015, 7 pp.

The classical 0-order X-wave is a limited-diffraction solution for the scalar wave equation and provides good beam focusing along a large depth, for instance, in high-resolution ultrasonic imaging. In this work, only the negative-time parts of 0-order X-waves are used like driving signals for a Bessel array in order to produce a highly focused acoustic field over a line. This approach maintains the advantages provided by the conventional 0-order X-waves, large depth of focused field with low lateral beam spreading, using only one emission shot. Some achievements obtained by using the proposed technique are a low energy and lower cost to drive the piezoelectric elements while maintaining a similar depth of field and beamwidth as those of the conventional method, a lower space extension of sidelobes, and easier control of the electrical driving system. Theoretical and experimental results support these hypotheses, and confirm the improvements obtained.

Acknowledgments

This work and the Postdoctoral Research of Dr. L. Castellanos in SEPI-ESIME-IPN are being supported by CONACyT Estancias Postdoctorales-Convocatoria 2013(1). This work was developed at Instituto Politécnico Nacional, ESIME Zacatenco, Ultrasonic Research Laboratory (Project No. SIP20143954), and the Instituto de Tecnologías Físicas y de la Información del CSIC (Ultrasonic Systems and Technologies Group), R&D National Plan of Spain DPI2011- 22438, Madrid.