Design of Ultrasonic Transducers with Multiple Acoustic Matching Layers for Medical Application

For high-efficiency wide-band piezoelectric transducers, a design method based on the synthesis theory of multiple-mode filters is presented. This design method has the advantages that it retains phys- ical intuition and can find optimum values of these matching layers by using iterative calculation techniques. An air-backed disk transducer with triple matching layers has been built to illustrate this design ap- proach, and good agreement between theory and experiment has been achieved. The transducer has SS-percent 6-dB fractional bandwidth, 3.2-dB round trip insertion loss, and less than l-dB passband ripple. Moreover, a prototype linear array probe with triple matching layers has been produced and has been used in an ultrasonic diagnostic equip- ment. Ultrasonograms with high resolution were obtained.