应用于水下光通信的菲涅尔透镜研究

发布时间：2018-06-09 17:29

本文选题：水下光通信 + 菲涅尔透镜　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：随着激光技术的发展，水下无线光通信技术近年来成为研究的热点。它具有传输延迟小、传输数据量大，受环境影响低等优点，在水下对潜通信、海洋环境监测、水下无人机等多方面发挥重要的作用。由于海水介质吸收和散射的影响以及海水通信信道的随机多变，，水下传输的光信号衰减严重，严重影响了光信号的接收，因此无线光通信系统多采用反射式结构的光学接收系统以增加光通信距离及减少误码率。但是反射式光学天线存在体积重量大、结构复杂、造价高等问题。本文提出了以菲涅尔透镜作为水下光通信系统的接收天线方案。理论分析、设计了菲涅尔透镜，并仿真了透镜接收水下激光信号的聚焦光斑参数，实验测量结果与理论分析一致。研究结果表明：菲涅尔透镜做为水下光通信系统接收天线具有面积大、焦距短、厚度薄、质量轻、成本低等优点。论文的主要研究内容如下：论文首先研究了海水通信信道的特性，理论分析了海水中各成分的吸收和散射特性，根据经验模型拟合其特性曲线，并且在光学仿真软件Lighttools中模拟了海水的Mie（米氏）散射特性；根据水下光通信光学接收系统的要求及菲涅尔透镜的通用设计公式设计了菲涅尔透镜，并计算得到该菲涅尔透镜各环带的楞元顶角参数。为进一步聚焦光斑，设计了光锥形二次聚光器，并对聚光效果进行了分析；根据设计参数采用三维制图软件Solidworks建立菲涅尔透镜模型，将菲涅尔透镜模型导入到Lighttools中，模拟菲涅尔透镜对太阳光及单色光的聚焦能力，分析了菲涅尔透镜的色差；在Lighttools中建立海水散射体模型模拟了532nm激光在海水中传输产生的散射光的聚焦情况。根据菲涅尔透镜的结构特点及模拟的散射结果，分析了菲涅尔透镜的光损失机理和影响水下无线光通信接收端聚光器光学效率的因素。分别在实验室内水槽和威海近海海域采用菲涅尔透镜进行了水下光传输接收实验研究，测量了光在不同传输距离时的接收光斑，并对接收光进行了三维能量分析，实验结果与理论分析一致，验证了菲涅尔透镜做为水下光通信系统接收天线的可行性。
[Abstract]:With the development of laser technology, underwater wireless optical communication technology has become a hot spot in recent years. It has the advantages of small transmission delay, large amount of transmission data, low environmental impact, etc. It can be used for underwater communication and marine environment monitoring. Underwater unmanned aerial vehicle (UAV) plays an important role in many aspects. Due to the influence of the absorption and scattering of seawater medium and the random variability of sea water communication channel, the optical signal transmitted under water attenuates seriously, which seriously affects the reception of optical signal. Therefore, optical receiving systems with reflective structure are used in wireless optical communication systems to increase optical communication distance and reduce bit error rate (BER). However, the reflective optical antenna has many problems, such as large volume and weight, complex structure and high cost. In this paper, Fresnel lens is used as the receiving antenna of underwater optical communication system. The Fresnel lens is designed and the focal spot parameters of the lens receiving underwater laser signal are simulated. The experimental results are in agreement with the theoretical analysis. The results show that Fresnel lens has the advantages of large area, short focal length, thin thickness, light mass and low cost as receiving antenna of underwater optical communication system. The main contents of this paper are as follows: firstly, the characteristics of seawater communication channel are studied, the absorption and scattering characteristics of each component in seawater are analyzed theoretically, and the characteristic curves are fitted according to the empirical model. The Mieh scattering characteristics of seawater are simulated in the optical simulation software Lighttools, and the Fresnel lens is designed according to the requirements of optical receiving system for underwater optical communication and the general design formula of Fresnel lens. The vertex parameters of corrugated elements in each ring of the Fresnel lens are calculated. In order to further focus on the spot, the conical secondary concentrator is designed, and the effect of light concentration is analyzed. According to the design parameters, the Fresnel lens model is established by using 3D drawing software Solidworks, and the Fresnel lens model is imported into Lighttools. The focusing ability of Fresnel lens to solar and monochromatic light is simulated and the color aberration of Fresnel lens is analyzed. Based on the structural characteristics of the Fresnel lens and the simulated scattering results, the optical loss mechanism of the Fresnel lens and the factors affecting the optical efficiency of the optical concentrator at the receiver end of the underwater wireless optical communication are analyzed. The experimental study of underwater optical transmission and reception was carried out by Fresnel lens in the laboratory flume and the offshore waters of Weihai, respectively. The receiving spot of light at different transmission distances was measured, and the three dimensional energy analysis of the received light was carried out. The experimental results agree with the theoretical analysis and verify the feasibility of Fresnel lens as the receiving antenna of underwater optical communication system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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