Reduction of transmitted 2nd harmonics using an adaptive method by simulated annealing

Tissue harmonic imaging is often the preferred ultrasound imaging modality due to its ability to improve image quality by suppressing reverberations [1]. The method relies on the 2
^nd
harmonic of the transmit frequency being generated as the waves propagation in tissue. For such imaging the backscattered harmonics are weak, so for successful imaging the level of undesired transmitted 2
^nd
harmonic must be about 30dB below the fundamental energy. Transmitted 2
^nd
harmonic energy may be caused by both linear, e.g. sidebands in the transmit spectrum, and nonlinear effects in the transducer and transmitting electronics. This paper presents a method where the electrical excitation waveforms are optimized to suppress the 2
^nd
harmonic components of the emitted ultrasound pulses.