Figure 1.

Schematic of the first design incorporating dual-frequency transducers for the purpose of contrast detection (top). Odd numbered elements had a center frequency of 2.8 MHz with a fractional bandwidth of 80% while the even elements had a center frequency of 0.9 MHz with a fractional bandwidth of 50%. Odd numbered elements were used for imaging superharmonics generated by nonlinear vibrations of microbubbles excited with a low-frequency pulse provided by the even elements. A photograph of the actual transducer is shown after the elevational lens has been added (bottom). Figure reprinted with permission from [46].