Zhang Hao, Kuschmierz Robert, Czarske Jürgen, Fischer Andreas
Opt Express. 2016 May 30;24(11):12130-41. doi: 10.1364/OE.24.012130.
Simultaneous position and velocity measurements enable absolute 3-D shape measurements of fast rotating objects for instance for monitoring the cutting process in a lathe. Laser Doppler distance sensors enable simultaneous position and velocity measurements with a single sensor head by evaluating the scattered light signals. The superposition of several speckles with equal Doppler frequency but random phase on the photo detector results in an increased velocity and shape uncertainty, however. In this paper, we present a novel image evaluation method that overcomes the uncertainty limitations due to the speckle effect. For this purpose, the scattered light is detected with a camera instead of single photo detectors. Thus, the Doppler frequency from each speckle can be evaluated separately and the velocity uncertainty decreases with the square root of the number of camera lines. A reduction of the velocity uncertainty by the order of one magnitude is verified by the numerical simulations and experimental results, respectively. As a result, the measurement uncertainty of the absolute shape is not limited by the speckle effect anymore.
同时进行位置和速度测量能够对快速旋转的物体进行绝对三维形状测量，例如用于监测车床的切削过程。激光多普勒距离传感器通过评估散射光信号，利用单个传感器头实现同时进行位置和速度测量。然而，在光电探测器上，具有相同多普勒频率但相位随机的多个散斑叠加会导致速度和形状不确定性增加。在本文中，我们提出了一种新颖的图像评估方法，该方法克服了由于散斑效应导致的不确定性限制。为此，使用相机而非单个光电探测器来检测散射光。这样，每个散斑的多普勒频率可以单独评估，并且速度不确定性随相机行数的平方根降低。数值模拟和实验结果分别验证了速度不确定性降低了一个数量级。结果，绝对形状的测量不确定性不再受散斑效应限制。
