Theoretical and Experimental Investigation of UltrasonicFocusing with Annular Phased Array

Abstract

The focused acoustic field generated by an annulararray transducer and its reflection field on a solid–liquid interfaceare investigated theoretically and experimentally. Theoretically, theconcise analytic expressions about the radiation and reflection acousticfields of the annular phased array are obtained by the ray approachmethod (saddle-point method). In experiment, an annular transducer with8 equal-area elements is designed and fabricated, and a series ofexperiments about the radiation acoustic field and its reflection on theliquid-solid interface are carried out. The experimental characteristicsof the transducer are in good agreement with the numerical ones. Itshows the correctness of the theoretical result and the feasibility ofdynamic focusing of the experiment system. With the maximum amplitudeand its emergence time of the reflection wave, we can acquire theinformation and the imaging of the reflection interface by the annularphased array dynamic focusing.