为了从聚焦超声声场纹影图像直接重建声场声压分布图像, 首先根据水中声波与光波的作用规律, 利用Zernike相衬技术得到纹影系统中空间声压分布与纹影图像中光强的关系, 再通过纹影系统获得聚焦超声声场实时图像, 最后根据纹影系统的物理特性经过反投影重建算法重建出凹球壳聚焦超声换能器的空间声压分布。分析可知, 理论声焦域横向与声轴大小分别为0.15 mm、1.4 mm, 重建声场电功率为12 W时横向最接近为0.25 mm,30 W时声轴最接近为1.35 mm。与球壳换能器的理论声压分布进行对比的结果表明, 该方法具有一定可行性, 可以用于聚焦超声换能器的声场分布检测。

In order to rebuild the pressure distribution from the schlieren image of focused ultrasound field directly, relationship was presented firstly between the spatial distribution of sound pressure and the intensity of schlieren image getting by Zernike phase contrast system based on the acousto-optic effect. Then the real-time sound image of focused ultrasound was obtained by the schlieren system. Due to the physical property of schlieren system, the spatial sound pressure distribution of a concave spherical shell focused ultrasonic transducer could be reconstructed by using a back-projection reconstruction algorithm lastly. According to analysis, when the electric power is 12 W, the horizontal size of reconstruction focal region is 0.25 mm closest to the theoretical 0.15 mm and when the electric power is 30 W, the acoustic axis size of reconstruction focal region is 1.35 mm closest to the theoretical 1.4 mm. Results compared with the theoretical sound pressure distribution of the spherical shell transducer show that this method has certain feasibility for ultrasonic transducer measurement.