基于非衍射波的高帧率(high frame rate,HFR)超声成像的前提是发射阵列波(array beam)声场,但由于阵列波的正弦函数特征使对超声发射信号加权处理变得比较困难,导致了发射系统复杂.针对这一问题,本文提出一种有效的解决方案.基于傅里叶变换理论,从方波的能量成分主要集中在基波这一特性出发,采用单值方波对超声传感器发射信号进行加权,用一个功率信号源和简单的电子开关网络实现了HFR系统中所需要的发射电路.实验表明,这种方案对HFR的成像质量几乎没有什么影响,但大大简化了HFR成像系统,这为HFR超声成像方法在现有B超声系统上的实现提供了一个可行的方法.
Array beam field is a necessary condition for high frame rate(HFR) ultrasonic imaging system according to the non-diffraction wave theory. However, the sine function characteristic of array beam waves makes it more difficult to weight the ultrasonic wave transmission signal so the transmission system is very complex. To solve this problem, this paper proposes an effective solution. Based on Fourier transform theory, the energy component of the square wave focuses mainly on the fundamental wave. In this paper a kind of square wave with a single value is utilized to weight the transmitted signals from an ultrasonic transducer. Thus only one power signal source and a very simple electronic switch system can be used to achieve this kind of transmission circuit in the HFR system. Experiments show that such an option has little impact on the image quality of the HFR, however it greatly simplifies the HFR ultrasound imaging system.