Dynamic focusing of acoustic wave utilizing a randomly scattering lens and a single fixed transducer

摘要

In this study, we report a randomly scattering lens (RSL) coupled with a single fixed transducer to realize dynamic acoustic focusing. This acoustic lens is composed of randomly distributed acoustic scatterers, and a single ultrasound transducer is fixed on one side of the lens. Benefitting from the high-order multiple scattering in the RSL, the ultrasound emitted by the single fixed transducer can be dynamically focused onto any desired point by manipulating the transmitting waveform. Then, we successfully apply such a single channel system to decode a photoacoustic image from the received ultrasound signal. Further studies demonstrate that the focusing ability of the proposed system can be approximated by a classic acoustic lens. Its axial resolution is related to the speed of sound and the bandwidth of the signal; its lateral resolution depends not only on the ultrasound frequency but also on the numerical aperture of the RSL; furthermore, the image quality improves as the numerical aperture increases. In comparison with other acoustic focusing methods, dynamic focusing achieved by the proposed system needs neither special materials or delicate structures nor a large number of channels. Therefore, the proposed system could find broad applications ranging from medical ultrasound imaging to nondestructive detection.