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 sum- and 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, omega-p, 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, omega-i, to produce scattered signals at omega-i +/- (omega-p/2). In this study, the ability of these signals to accurately size and resolve bubbles, both singly and in arrays, has been studied.