Experimental evaluation of effects of absorption layer on parametric ultrasound

Abstract

This study investigated the effects of absorption attenuation on parametric ultrasound (US) for application to low-frequency (LF) US measurement and imaging. The effects of an absorption layer on the sound field and pulsed wave of parametric US at several hundred kilohertz in water were experimentally evaluated via a comparison with LF US directly radiated from a transmitter. The results indicate that the variations of the shape and amplitude of parametric US field and waveform due to the insertion of an absorber were more significant than those for LF US at the same frequency. However, these effects can be mitigated when an absorber is inserted at a far distance from a transmitter. These results suggest that for the application of parametric US in measurement and imaging, a low-absorption medium must be inserted between a transmitter and absorbing material to be evaluated in order to grow secondary waves sufficiently.