基于涡旋光场水下激光雷达空间滤波技术研究

A spatial filtering technology in underwater lidar based on vortex light field

基于水下激光雷达目标回波和多次散射杂波空间相干性的差异,利用涡旋光场形成的特点,使用螺旋相位板附加环状掩膜板形成空间滤波装置,将目标反射信号与多次散射信号进行空间分离。由于目标反射信号具有良好的空间相干性,经过螺旋相位板后会形成涡旋光,而散射杂波由于其空间相干性被多次散射破坏,会按照散射规律呈现类高斯的中间强边缘弱的分布。利用环状掩膜板只容许涡旋光通过,到达探测器,从而降低了散射对测距的影响。上述空间滤波装置应用于载波调制相位测距及脉冲测距水下激光雷达系统中,均可以大幅提高浑浊水体中目标的测距精度。

Based on the difference in spatial coherence between target echo and multi-scattering clutter in underwater lidar system,a spiral phase plate and an additional ring mask plate were proposed to form a spatial filter to separate the target reflected signal from the multi-scattered clutters.Due to the good spatial coherence of the target reflected signal,vortex light will be formed after the target reflected signal passing through the spiral phase plate,while the spatial coherence of scattering clutter will be destroyed by multiple scattering and presented a Gaussian-like distribution according to the scattering law.The use of ring-shape mask plate only allows vortex light to pass through and reach the detector,thereby reducing the effect of scattering on ranging.The above-mentioned spatial filtering device is applied to radar-lidar and pulse ranging underwater lidar systems,which can greatly improve the ranging accuracy of targets in turbid water.