中文摘要：

本文基于离焦测距原理，提出一种利用单镜头双相机测量运动颗粒三维速度的方法。入射光经分束立方体分别进入两个工业相机，通过调节分束立方体与相机间的垫圈厚度获取同一对象两幅不同模糊度的图片，根据其模糊差实现运动颗粒在三维场中的定位，再结合单帧多曝光方法，获取其三维速度。通过拍摄慢速搅拌水流中颗粒运动并分析处理不同运动情况的颗粒图片得到了运动颗粒的三维速度，经计算与实验考察证明了其可行性。该方法解决了离焦二义性问题与速度方向二义性问题，为三维速度的测量提供了新的方向。

英文摘要：

Based on the principle of depth from defocus, a kind of method for the measurement of three-dimensional （3-D） velocity of moving particle using the single-lens dual-camera was proposed. The incident light was dispersed into two industrial cameras through the beam splitter prism. Two images with different blur degree for the same object were acquired by adjusting the thickness of the washers between the prism and the cameras. The orientation of the moving particle in the three-dimensional field was obtained from the difference of blur degree between the images, and then the 3-D velocity of the particles can be calculated combined with the single-frame multi-exposure method. The images recording the movement of particles in the water flow with slow agitation were processed and analyzed which lead to the calculating results of the 3-D velocity field of moving parti- cles. The feasibility of the method proposed was verified through the comparison of the calculating results and the experimental results. The method solves the problems of the ambiguity of both de- focus and the direction of velocity, as well as indicating a new way for the measurement of 3-D velocity.