C形纵剖面部分球冠换能器结构对声焦域的影响

Influence of the structure of partial spherical crown transducer with C-shaped vertical segment on acoustic focal region

在球带腔形聚焦超声换能器的基础上,设计一种C形纵剖面部分球冠聚焦超声换能器,研究其结构参数变化对声焦域形态的影响。通过建立的有限元仿真模型,分别讨论了换能器的球带高度和聚焦夹角与焦域形态的变化关系。结果表明,球带高度越高、聚焦夹角越大,其焦域尺寸越小,焦域长轴与短轴的比值越低,焦域趋近于圆形,尤其是当球带高度为1.6F(F为焦距)、聚焦夹角≥210°时,其焦域三轴尺寸均可达到亚波长尺度。为验证仿真结果的正确性,设计制作了一个可改变聚焦夹角的换能器并进行了测试,实验与仿真结果大致相符。设计的换能器相对于传统行波换能器,焦域形态得到了明显改善,能够压缩焦域长短轴之比,有效提高聚焦精度,为改善聚焦超声换能器焦域形态提供了一种设计方法。

Based on the spherical zone cavity focused ultrasound transducer, a partial spherical crown focusing ultrasound transducer with C-shaped vertical segment is designed to study the influence of its structural parameters on the shape of acoustic focal region. Through the established finite element simulation model, the relationships of the spherical zone height and the focused angle of the transducer with the shape of focal region are discussed. The results show that the higher the spherical zone height and the larger the focused angle, the smaller the focal region size, the lower the ratio of long axis to short axis of the focal region, so that the focal region tends to be round;especially when the spherical zone height is 1.6 focal length and the focused angle ≥ 210°, the triaxial dimension of the focal region can all reach the sub-wavelength scale. In order to verify the correctness of the simulation results, a transducer that can change the focused angle is designed and tested. The experimental results are in agreement with the simulation results.Compared with the traditional travelling wave transducer, the designed transducer can improve the shape of focal region obviously, compress the ratio of long axis to short axis of the focal region and improve the focused accuracy effectively,which provides a design method of improving the focal region shape of the focused ultrasound transducer.