根据菲涅耳衍射原理给出了半波带声学透镜的几何公式，考察半波带声透镜的会聚能力，建立半波带声透镜的二 维轴对称物理模型，并采用有限元分析方法对模型控制方程———Helmholtz 方程进行仿真计算.基于所建物理模型，得出了频 率、半波带个数以及声透镜材质的透射系数对聚焦能力的影响.仿真结果表明，半波带个数的增加可调高焦点处的声压级，同 时焦点的位置变大; 而频率越低，焦距越小; 透射系数越大，焦点处声压级越小.最后，通过制作简易声学透镜验证物理模型的 有效性.

In order to investigate the focusing ability of half wave acoustic band lens，the geometric formula of the two-dimensional ( 2D) half wave acoustic lens is obtained by using the Fresnel diffraction principle. A 2D axisymmetric physical model of the half- wave acoustic lens is established，and the finite element method is used to simulate the model-Holmholtz equation. Based on the physical model，the influence of the frequency，the number of half band and the transmission coefficient of the acoustic lens on the focusing ability are investigated. The results show that the increase of the number of half-band increases the sound pressure level at the focal point and change the position of the focal point. The lower the frequency is，the smaller the focal length is. The larger the transmission coefficient is，the smaller the sound pressure level at the focal point is. Finally，the effectiveness of the physical model is verified by making a simple acoustic lens.