后向散斑记忆水下目标激光远距离成像的理论与实验研究

Long-range laser imaging of underwater objects has been a major difficulty in maritime search-and-rescue, ocean exploration, and military reconnaissance and so on. The key of this problem primarily ascribes the water scattering. This project, focusing on the Long-range imaging of underwater laser, intends to use the theoretical analysis, numerical simulation and optical experiments for further research on the memory effect of backscattered speckle of turbid water, to propose a real-time speckle array imaging method with different view angles for underwater objects. Researches Include: theoretical calculations of the memory effect of backscattered speckle for turbid water; construction of the theoretical simulation model of backscattered speckle; experimental study of the spatial intensity to the view-angle speckle correlation and its influencing factors; research on memory mechanism of objects information in backscattered speckle; finally designing the experiment program, implementing the experimental research and ascertaining the imaging method. The study of this subject will break through the current distance constraints of underwater laser imaging, and providing the technical approach for the long-range laser imaging of underwater objects.

水下目标的激光远距离成像是海事搜救、海洋勘探、军事侦察等领域面临的重大难题,而水体散射是导致这一问题的根本原因。本课题以水下激光的远距离成像为主题，拟采取理论分析、数值模拟和光学实验相结合的方式，通过研究浑浊水体后向散斑的记忆效应，提出一种用于水下目标激光远距离探测的视角散斑记忆成像方法。具体研究内容包括：理论分析浑浊水体的后向散斑记忆特性；构建后向散斑视角记忆的理论仿真模型；实验研究后向散斑的空间强度相关性及其影响因素；研究视角散斑中目标信息的记忆机理；最后开展成像验证实验，建立成像方法。本课题的研究将突破目前水下激光成像的距离制约，为水下目标的激光远距离探测开辟新的技术途径。

本项目首先研究实验室等效实验方法，建立开展水下目标激光远距离探测的等效实验环境。对比、分析多种粉末材料，通过在自来水中添加不同质量的粉末颗粒，模拟浑浊程度不同的水体，在实验室的有限空间内，实现并标定水下远距离探测的等效环境，同时实验对比了不同光束形态激光的水下远距离传输性能。其次，基于衍射传输理论模拟散斑成像过程，揭示影响散斑颗粒度和衬比度的因素，理论分析混浊水体的激光散斑记忆特性，构建理论仿真模型，实验研究水下目标的透射散斑记忆效应，并完成目标物体透射散斑的相位迭代重建成像。再者，采用激光周视扫描和非扫描方法，对水下远距离运动小目标的探测问题进行建模仿真，分析影响因素，完成探测系统设计。最后，鉴于目前水下激光实现远距离探测的困难，结合水声技术，对下一步开展水下目标声光散斑成像作出展望与建议。