Acoustic bubble sizing by combination of subharmonic emissions with imaging frequency

The non-linear response of a bubble to an acoustic field results in the scattering of sumand difference-frequencies when two frequencies are incident. This has in the past been used to size bubbles. since it is only when the pump frequency. wp' is near the bubble resonance that the non-linear effects are observed. In addition. the subharmonic frequency emitted by the bubble can combine with the imaging frequency. Wi. to produce scattered signals at Wi ± (Wp /2). In this study. the ability of these signals to accurately size and resolve bubbles. both singly and in arrays. has been studied.