Development of ultrasound transducer with double peak type frequency characteristics for harmonic imaging ultrasound diagnostic equipment

A new type ultrasound transducer with double peak type frequency characteristics was proposed as an ultrasound transducer for harmonic imaging. The peak on the low frequency side in the frequency characteristics is used to transmit ultrasound into tissues or a microbubble ultrasound contrast agent. Another peak on the high frequency side is used to receive the 2nd harmonic component from microbubble ultrasound contrast agent or those generated in tissues. The proposed ultrasound transducer has a stacked structure of piezoelectric ceramic vibrator and subvibrating plate on the backing. The thickness of piezoelectric vibrator should be determined in such a way that the λ/2 resonant frequency of piezoelectric vibrator coincides with the second harmonic frequency, and that of subvibrating plate should be determined in such a way that the λ/4 resonant frequency of subvibrating plate coincides with the frequency of fundamental wave, respectively, for the proposed transducer