声束在固体中的聚焦及其在声成像中的应用

Focusing into solids and its application in acoustic image

本文主要研究表面换能器阵列在固体中产生的聚焦及轴上焦场的情形,讨论各级次焦点处场的值与条宽阵元的关系.用数值计算求出某一频率时不同的阵元宽度的焦场分布,并从实用角度出发,讨论将这种聚焦用于无损检测和成像时,横向和纵向分辨率等问题,为了进一步说明理论,做了一些探索性的实验.

Focusing into solids by transducer arrays and acoustic field distribution on focal axis are studied in this paper. The relation between source element width and field strength at different order of focuses is discussed. Numerical calculation is used to get focal field distribution when the element width changed. Some practical problems such as the minimum distinguished frequency, transversal and longitudinal resolution are investigated when this kind of focusing is considered to find applications in NDT and Acoustic Image. Some explorative experiments have been done to demostrate the theory.