Development of three-dimensional measuring system of velocity distribution using circular shifting

圆移法能够使用单个电视摄像机和图像移位装置对粒子的运动进行三维测量。通过在电视摄像机镜头上引入折射镜，示踪粒子的图像在像平面上发生位移，该位移与电视摄像机与示踪粒子之间的距离有关。在电视摄像机曝光过程中，当折射镜以高速(3600 r/min)旋转时，由于旋转偏移，图像上会出现圆形条纹。由于圆形条纹的大小与测量点到相机的距离成反比，因此每个条纹包含关于测量点的3D信息，并且可以通过处理条纹图像来提取该信息。本文介绍了圆移法和立体视法相结合的方法。通过这种组合，弥补了各种方法的缺陷，提高了测量精度。

Circular shifting method enables a three-dimensional measurement of particle movement using a single TV camera and an image-shifting device. By introducing a refractor on the TV camera lens, the image of the tracer particle undergoes a displacement on the image plane that is related to the distance between the TV camera and the tracer particle. When the refractor is rotated at high speed (3,600 r/min) during the TV camera exposure, circular streaks appear on the image due to the rotational shift. Since the size of the circular streak is inversely proportional to the distance of the measuring point from the camera, each streak contains 3D information about a measuring point, and this information can be extracted by processing the streak image. In this paper, combination method between circular shifting and stereovision method is introduced. By this combination, defects of each method are compensated and measurement accuracy is improved.