运动界面上反射超声散斑空间运动的研究

Research on spatial motion of ultrasonic speckles back-scattered from an interface in motion

在Kirchhoff衍射理论的基础上 ,应用随机信号相关原理 ,推导了作刚体运动的界面上反射超声散斑在空间运动时 ,保持其复振幅相关的必要条件 .由此得到超声散斑的空间运动公式 .界面、超声散斑和超声接收探头之间的相对运动 ,导致界面孔径的改变 .分析表明 ,在保持界面孔径相关的条件下 ,界面所允许的最大平移量和转角值 ,与声源位置、接收用聚焦探头的数值孔径、超声入射角以及观察角有关 .应用数字相关技术和三维扫描信号采集系统 ,根据散斑场子集相关系数的单峰性质 ,对超声散斑空间运动公式进行了实验验证 .实验结果表明 。

Based on the Kirchhoff diffraction theory, the necessary condition for keeping the correlation of the complex amplitudes of the ultrasonic speckles back scattered from an interface in rigid body motion is deduced by applying the correlation principle. Consequently, the spatial motion formulas of ultrasonic speckles are obtained.The aperture of the interface is changed due to the relative motion of the interface with respect to the speckles and the receiving focus probe. Analysis shows that under the condition of keeping the correlation of the aperture, the values of the maximum translations and the rotation angles of the interface depend on the position of the ultrasound source, the numerical aperture of the focal receiving probe, the ultrasonic incident angle and the observation angle. A three dimensional scanning system for measuring speckles was set up by the authors. According to the single peak property of the correlation coefficient of the sub region pairs of the ultrasonic speckle field, the spatial motion formulas of ultrasonic speckles are verified experimentally by using the digital correlation technique. The experimental result shows that the spatial motion formulas of ultrasonic speckles developed theoretically are correct.