Development of acoustical lens for catheter ultrasonic probe

声透镜不仅在水下应用中，而且在医学应用中，都有可能改善换能器的声学特性。作者对导管超声透镜的声学设计方法进行了研究。首次研制了一种适用于水下应用的三单元大口径声透镜。特定的声透镜基本上通过商业上可获得的光学透镜设计程序来设计。在制作前，采用二维或三维时域有限差分法（FDTD）对透镜的声学特性进行了波动理论验证。我们可以在水中获得很好的图像。在第二阶段，制作了一个40 mm的中型透镜，其比例因子为10。不仅测量了垂直入射时的声学特性，而且测量了斜入射时的声学特性。计算结果与实验结果吻合较好。从而获得对导管超声探头透镜设计方法的认识。

Acoustic lens has the possibility of improvement of acoustic characteristic of transducer not only in underwater application but also in medical application. The authors researched about the development of suitable acoustic designing method for catheter ultrasonic lens. A large acoustic lens composed of three-elements was firstly fabricated for underwater application. Specified acoustic lenses were basically designed by commercial available optical lens designing program. A 2D or 3D Finite Differential Time Domain (FDTD) method was used for wave-theoretical verification of acoustic characteristic of lenses in advance of fabrication. We can obtain fine images in water. In the second phase, the single midsize lens of 40mm whose scale factor was 10 was fabricated for catheter probe. The acoustic property was measured not only on normal incidence but also on oblique incidence. Calculated results agreed well with experimental results. We could obtain the acknowledges about lens designing method for catheter ultrasonic probe lens.