大气湍流对LIF探测海面溢油影响的BRRDF仿真研究

doi:10.3964/j.issn.1000-0593(2024)05-1379-07

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摘要：及时定位海面溢油事故发生地并监测海面溢油信息对海洋污染治理和海洋生态环境保护有重要意义。激光诱导荧光（LIF）可搭载于无人机构建LIF雷达系统并应用于海洋环境监测。LIF雷达系统以大气为传输信道，大气湍流会导致信号衰落。双向反射再辐射分布函数（BRRDF）利用受激辐射荧光光子的权重、位置和方向描述物质的荧光特性，为LIF探测海面溢油提供理论指导。基于大气湍流理论和蒙特卡罗方法模拟海面溢油的受激辐射荧光过程，建立光子传输模型进行海面溢油BRRDF的仿真研究。仿真分析不同湍流强度下，光强闪烁、光束漂移、光束扩展效应对海面溢油BRRDF的影响。仿真结果表明，海面溢油受激辐射荧光信号具有各向同性，其强度与激发光的强度成正比。光束漂移效应对荧光漂移范围影响微弱，可以忽略；在弱大气湍流下（湍流强度参数σ²_R＜1），BRRDF所表征的荧光信号强度集中在2×10^-5～5×10^-5范围内，荧光光斑半径由1 mm扩展至5 mm，LIF雷达系统可以正常进行探测工作；大气湍流强度到达中等后（σ²_R≈1），荧光信号强度在10^-5～10^-4范围内波动，荧光光斑半径扩展至15 mm，此时大气湍流的不利影响无法忽视，LIF雷达系统探测到的荧光信号不够稳定，最终导致光谱不理想。在实际探测中，可通过适当提高探测器性能参数来增强系统的抗湍流能力。强大气湍流下（σ²_R＝25），出现光斑破裂现象，荧光信号分散并衰落至某一阈值之下，LIF雷达系统无法探测到荧光信号。文中的分析与提出的可行的研究建议，为LIF探测海面溢油相关研究提供参考依据，对LIF雷达系统设计具有一定的参考价值。

关键词：激光诱导荧光；双向反射再辐射分布函数；海面溢油探测；大气湍流；蒙特卡罗法

Abstract：Laser-induced fluorescence (LIF) can be integrated into unmanned aerial vehicles to build LIF radar systems for marine environmental monitoring. The LIF radar system operates in the atmosphere, where atmospheric turbulence induces signal attenuation. The Bidirectional Reflectance Distribution Function (BRRDF) can describe the fluorescence characteristics of oil-contaminated seawater. Based on the theory of atmospheric turbulence and the Monte Carlo method, a BRRDF model has been developed by us for studying oil-contaminated seawater. The model was used to simulate the BRRDF of oil-contaminated seawater under irradiance scintillation, beam wander, and beam spreading conditions. The simulation results demonstrate that the fluorescence signals exhibit isotropy, and their intensity is directly proportional to the intensity of the excitation light. The influence of beam wander on the fluorescence signals is weak and can be neglected. Under weak atmospheric turbulence conditions(Turbulence intensity parameters σ²_R＜1), with the fluorescence signal intensity concentrated within the range of 2×10^-5 to 5×10^-5 and the fluorescence spot radius expanding from 1 to 5 mm, the LIF radar system can operate normally in the turbulent channel. Under moderate atmospheric turbulent conditions (σ²_R≈1), the fluorescence signal fluctuates from 10^-5 to 10^-4. The fluorescence spot radius expands to 15 mm. The LIF radar system's resistance to turbulence needs to be improved by appropriately increasing the aperture of the receiving lens. Under strong atmospheric turbulent conditions (σ²_R＝25), the LIF radar system connot detect the fluorescence signal. The analysis and discussion in this study can provide references for the design and optimization of LIF radar systems.

Key words：Laser induced fluorescence; Bidirectional reflectance and reradiation distribution functions; Oil spill detection on the sea; Atmospheric turbulence; Monte Carlo method

收稿日期: 2023-03-13 修订日期: 2023-09-11

中图分类号:

P733.3

基金资助: 国家自然科学基金面上项目（62173290，62173289），河北省中央引导地方科技发展资金项目(236Z1704G)，河北省自然科学基金青年科学基金项目（F2021203084），河北省创新能力提升计划项目（22567626H）资助

作者简介: 谢贝贝，女，1989年生，燕山大学信息科学与工程学院讲师 e-mail: beibeixie@ysu.edu.cn

引用本文:

谢贝贝，赵佳伟，周炫宇，张晓丹，刘俣佳. 大气湍流对LIF探测海面溢油影响的BRRDF仿真研究[J]. 光谱学与光谱分析, 2024, 44(05): 1379-1385.
XIE Bei-bei, ZHAO Jia-wei, ZHOU Xuan-yu, ZHANG Xiao-dan, LIU Yu-jia. BRRDF Simulation Study on the Influence of Atmospheric Turbulence on LIF Detection of Sea Surface Oil Spill. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(05): 1379-1385.

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