随着透明海洋战略的提出, 低成本的凝视成像装备在水下光学成像中独具优势。然而, 后向散射和成像目标难以分离, 远距离凝视成像极为困难。更为严重的是, 在采集到有效目标图像之前, 过强的后向散射噪声已经使图像提前饱和, 无法进行后续处理。本文提出了短相干照明与偏振成像相结合的水下远距离成像方法, 利用短相干光源照明简化后向散射与成像目标的分离过程, 同时, 采用偏振技术有效抑制后向散射, 防止图像提前饱和, 保障目标图像的有效采集。为此, 搭建了大型水下光学成像实验平台, 并对22 m的远距离水下目标进行了成像试验研究。试验结果表明, 该复合成像方法获得的图像信噪比由0.50 dB提高到13.57 dB, 设备的抗提前饱和能力提高了1.42倍, 优于传统的偏振成像, 可以为大范围水下光学监控提供技术支撑。

Considering the development of transparent ocean strategy, low-cost staring imaging equipment have unique advantages in underwater optical imaging. However, it is difficult to separate the backscattering and imaging target, as well as to capture a clear image at a long distance. More importantly, before acquiring the effective target image, the strong scattering noise saturates the image and prevents subsequent processing. Thus, we propose a novel imaging method that combines short coherent illumination and polarization imaging. The short coherent illumination simplifies the separation of the backscattering and imaging target while the polarization technology prevents image saturation in advance and ensures the effective acquisition of the target image. In addition, we built a large-scale underwater optical imaging platform and conducted imaging tests at a long-distance of 22 m. The experimental results showed that the signal-to-noise ratio increased from 0.50 dB to 13.57 dB, and the anti-image early saturation ability of the device increased 1.42 times. These results are superior to the traditional polarization imaging. The proposed composite imaging method can provide technical support for large-range underwater optical monitoring.