基于无散射参照偏振成像技术的水下目标光学检测

摘要：

光学偏振成像系统能够基于水体散射噪声与目标信号之间的退偏振特性差异有效地抑制光散射效应对水下目标检测效果的影响。 然而， 传统偏振检测方法需要事先在图像无目标区域对水体后向散射光的偏振度进行测量， 并且假设目标为完全非偏振特征。 当水体后向散射场景没有呈现在光学成像系统视场中或者目标具有偏振明显特性时， 上述检测方法失效。 针对该问题， 通过测量水下场景的平行偏振与正交偏振分量， 提出了偏振减方法对水体散射噪声与目标信号的退偏振特性进行正确估计， 并且在石英比色皿容器中对所提方法的可靠性进行了实验验证。 结果表明， 偏振减方法适用于无散射背景参照的情形， 并可以检测水下环境中表面光滑的保偏目标。

For conventional optical polarization imaging of underwater target, the polarization degree of backscatter should be pre-measured by averaging the pixel intensities in the no target region of the polarization images, and the polarization property of the target is assumed to be completely depolarized. When the scattering background is unseen in the field of view or the target is polarized, conventional method is helpless in detecting the target. An improvement is to use lots of co-polarization and cross polarization detection components. We propose a polarization subtraction method to estimate depolarization property of the scattering noise and target signal. And experiment in a quartz cuvette container is performed to demonstrate the effectiveness of the proposed method. The results show that the proposed method can work without scattering background reference, and further recover the target along with smooth surface for polarization preserving response. This study promotes the development of optical polarization imaging systems in underwater environments.