Instituto de Fisica, Universidade Federal de Alagoas, Maceio, AL, Brazil.
IEEE Trans Ultrason Ferroelectr Freq Control. 2011 Feb;58(2):298-304. doi: 10.1109/TUFFC.2011.1807.
In this paper, the scattering of an ultrasound zero-order Bessel beam by a rigid sphere in the off-axis configuration is studied. The beam is described through the partial wave expansion. The beam-shape coefficients which represent the amplitude of each multipole mode of the partial wave expansion are computed by numerical quadrature. Calculations are presented for both near- and far-field off-axis scattering. The far-field scattering is examined in both Rayleigh and geometrical acoustic limits. Results demonstrate that the scattered pressure in the off-axis case may significantly deviate from that in the on-axis configuration. In addition, the directive pattern of the scattered pressure is highly dependent on the relative position of the beam to the sphere.
本文研究了超声零阶贝塞尔波束在离轴配置下对刚性球体的散射。该波束通过分波展开来描述。通过数值求积计算了代表分波展开中每个多极模式的幅度的波束形状系数。给出了近场和远场离轴散射的计算结果。在瑞利和几何声学极限下研究了远场散射。结果表明，离轴情况下的散射压力可能会显著偏离轴上配置的情况。此外，散射压力的指向性图案高度依赖于波束与球体的相对位置。
