利用角谱方法分析超声换能器声场

INVESTIGATION OF ULTRASONIC FIELDS OF A TRANSDUCER USING THE ANGULAR SPECTRUM METHOD

叙述了角谱 (angularspectrum)的基本概念和利用角谱方法 (angularspectrummethod ,下称ASM)分析超声换能器声场的基本原理和具体实现 ,对平面活塞换能器和聚焦换能器在均匀媒质中的声场应用ASM进行了计算 利用一套精密三维扫描系统和针状水听器对上述换能器的声场进行了实验测量 。

The traditional method to calculate the ultrasonic fields of the transducers is using the Rayleigh Sommerfeld diffraction (RSD) formula which provides an exact analytical expression of linear fields for the transducer in homogeneous media through 2 D integral. However, in many cases, the analytical solution of RSD is unavailable and the direct numerical evaluation is time consuming. The angular spectrum method (ASM), based on 2 D FFT, provides a faster numerical approach for the analysis of the sound fields of arbitrary sources. In this paper, the basic concept of the angular spectrum and the principle of the angular spectrum method (ASM) are reviewed, then the steps of ASM algorithms are described. To solve the problem of spatial aliasing, how to choose such parameters as the angular range and the spatial sampling interval is discussed. As a check of our ASM algorithms, the forward propagated ultrasonic fields of transducers in homogeneous media are calculated by ASM and RSD integral, respectively. Experimentally the ultrasonic fields are measured by a 3 D scanning system with a needle type hydrophone. Two types of transmitting transducers, of which one is a planar radiator and the other is a concave type with the same frequencies, are used. It is shown that the ASM results agree reasonably with the RSD results and the measured data.