超声相控阵在多层媒质中的声场模式优化

针对超声在多层媒质中的传播特性,引入相位补偿因子并结合遗传算法, 提出了一种可对多层媒质进行声聚焦控制的方法.利用该方法对16×16二维超声相控阵在多层生物媒质中的多焦点声场模式进行了仿真,计算了生物媒质不同厚度层和不同吸收系数时的声场. 结果表明:该方法能优化多焦点声场模式,抑制旁瓣,提高声场增益,将声强最大限度地聚焦在目标区域内; 改变生物组织不同层的厚度和不同层的吸收系数,焦点位置不发生变化,但焦域内的声强会有所变化.

Optimization of phased array ultrasonic field in multi-medium

According to the ultrasonic propagation characteristics in the multi-medium, a control method of ultrasonic focus in the multi-medium is presented through introducing the phase compensation factors and using genetic algorithm. The patterns of multi-focus ultrasonic field generated by two-dimensional phased array consisting of 16? 16 elements are simulated in multi-biological tissue, and the ultrasonic fields are calculated under the various thicknesses and the various absorption coefficients of medium layer. The results show that this approach can optimize the patterns of multi-focus ultrasonic field and restrain side-lobe, which can improve the ultrasonic intensity gain and make the maximal ultrasonic intensity focus on the target area. When the thickness and the absorption coefficient of biological tissue are changed, the focus position remains unchanged, but the ultrasonic intensity of the focus area will change relatively.