水面溢油污染的主动式全偏振态成像检测方法研究

Oil spill has now become a major pollutant in water. The polarization imaging experiment of water-surface oil spill will be carried out using the full-polarized spectral imaging system based on the mechanics analysis of the polarization characteristics and transformation law of water-surface oil spill. The model relations between the oil spill type, thickness and the full-polarized spectral characteristics of water-surface oil spill will be established by processing analysis and feature extraction of the full-polarized spectral characteristics of water-surface oil spill. The model parameters will be optimized by contrasting inversion accuracy with experimental results.. Not only the radiant intensity and linear polarization information but also circular polarization information can be obtain in the project, and the interpretation level of water-surface oil spill may be improved greatly. Moreover, Inversion of oil spill can be carried on by measuring the polarization state change of the ctive beam. The intensity of polarized radiation component reflected from the water-surface oil spill can be increased because of completely linear polarization of the active light source, and the uncertainty of the incident beam polarization state can also be avoided by combining the full-polarized spectral imaging technology with the active remote sensing. The new inversion method of oil spill may be developed in this project based on traditional and modern radiometric remote sensing of oil spill, which will improve the accuracy of oil spill monitoring and contribute to the quantitative application of polarization remote sensing information for the large area of oil spill.

水面溢油是最常见的水体污染源之一。本项目在分析水面溢油污染偏振特性机理及其变化规律的基础上，利用主动式全偏振光谱成像系统开展水面各种溢油的全偏振光谱成像试验；通过水面溢油的全偏振光谱特征提取、处理分析研究，构建水面溢油种类、厚度与全偏振光谱特性的关系模型； 通过实验结果与反演精度对比，优化模型参数。. 本项目不仅能获取水面溢油的辐射强度和线偏振信息，同时又增加了圆偏振信息，这样大大增加了水面溢油的遥感解译水平。另外，本项目将主动式遥感与偏振光谱成像测量技术相结合，利用全偏振光谱成像系统观测主动光束偏振态的变化来进行水面溢油的反演研究，避免了入射光束偏振态不确定性，且大大提高光束中偏振辐射成分强度。力求在基于传统的水面溢油测定和现代辐射遥感监测水面溢油方法的基础上，发展水面溢油反演新方法，提高水面溢油遥感监测精度，使得主动式全偏振态测量技术为大面积水面溢油监测应用服务。

水面溢油会明显改变阳光、空气对水体的“输入”，仅少量的溢油就会使大片水域遭受污染，油污影响可持续十年以上。本项目对现有的被动式全偏振态测量成像系统进行技术改造升级及定标工作，结合主动偏振角可调平行光源，利用COMSOL软件进行水面溢油的全偏振光谱特性仿真和试验，研究水面溢油的全偏振光谱特性及其变化规律，建立水面溢油的全偏振特性实验统计响应模型。. 主动入射线偏振光照射在溢油和水体上，其反射辐射发生了变化，不再是完全线偏振光，其变化程度与反射目标特性有关，本项目的重要结果及关键数据为：随着主动入射线偏振光束偏振角的旋转，非偏振光强逐渐增大，在40º—50º偏振角下达到极值，而在入射偏振角接近90时，非偏振光强最小；溢油的总反射辐射相比于水体具有较高的强度，但随着油膜厚度的增加，强度反而减小，当油膜厚度达到一定程度后，反射辐射的强度不在明显变化；溢油和水体的偏振度（DOP）和线偏振度（LDOP）随着入射光束偏振角的增大而减小，但溢油对主动线偏振光的消偏作用明显大于水体，并且随着溢油厚度的增加，消偏能力逐渐增强，通过测量反射DOP（或LDOP）可以反演出溢油的厚度参数；圆偏振度（CDOP）随着入射光束偏振角的增大而减小，而在40°入射偏振角的照射下，溢油的圆偏振反射辐射突然增强可用于区分溢油与水体；溢油在约40°入射偏振角位置发生突变，而水体在50°入射偏振角位置发生突变，接收偏振角由约-45°变为+45°，即通过观察反射辐射偏振角突变位置，可区分溢油与水体。. 本项目将主动式遥感与全偏振光谱成像测量技术相结合，利用全偏振态光谱成像系统观测主动光束偏振态的变化来进行水面溢油的反演研究，避免了入射光束偏振态不确定性，且大大提高光束中偏振辐射成分强度，获取水面溢油的多维重要信息，使得主动式全偏振探测能够发展成为水面溢油污染遥感监测新技术奠定基础。