Development of acoustical lens for catheter ultrasonic probe

声透镜不仅在水下应用，而且在医学应用中都有改善换能器声学特性的可能。对导管超声透镜合适的声学设计方法进行了研究。首次制作了一种水下应用的大型三元声透镜。指定的声学透镜基本上是用市售光学透镜设计程序设计的。采用二维或三维时域有限差分（FDTD）方法在制作前对透镜的声学特性进行了波理论验证。我们可以在水中获得精细的图像。在第二阶段，制作单个40mm的中型透镜，其比例因子为10，用于导管探头。不仅测量了正入射声特性，还测量了斜入射声特性。计算结果与实验结果吻合较好。对导管超声探头透镜的设计方法有一定的认识。

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.