基于保偏光纤的溶液浓度测量系统的设计和实现

发布时间：2018-06-28 08:24

本文选题：菲涅尔公式 + 偏振分束器　；参考：《中北大学》2017年硕士论文

【摘要】：浓度是在日常生活和工业生产中用来表征介质液体特性的一个重要的特性参数。在众多领域中都需要精准的测量溶液的浓度或者折射率,比如基础研究、化工领域、医学诊断、食品制造,环境保护等方面。目前,已经有很多测量浓度的方法,应用较多物理实验方法主要是比重法,光学方法有衍射光栅法,杨氏干涉法、掠面入射法等。因为被测液体物质的性质不容易被光学方法改变,所以用光学方法测量液体折射率,再通过折射率与浓度之间的关系测量溶液浓度,是现阶段测量溶液浓度的流行趋势,与化学方法相比,应用越来越广泛。尤其,近年来涌现了一大批运用光学手段检测液体折射率的新方法,例如光波导多模干涉法、等离子共振法、共焦球面F-P干涉法,以及基于SPR光纤传感的方法。本设计通过推导溶液浓度和折射率的关系,引入了“压差比”的概念,采用光调制的方法制成了光纤传感溶液浓度测量系统来测量溶液浓度。本文内容涵盖溶液浓度测量系统的理论推导,流程设计,关键器件选型,系统的设计、搭建和调试。首先,介绍了测量溶液浓度的课题背景和意义,溶液浓度检测的常用物理实验法,传感器的国内外研究现状,溶液浓度检测方法的国内外研究现状,以及本课题的实验来源和实验内容,最终确定了本系统采用线偏振光基于保偏光纤测量溶液浓度的方法。其次,从光与物质的相互作用关系出发,根据洛伦兹的电子论、麦克斯韦关系和朗伯定律,建立起溶液在一定浓度范围内与折射率成线性关系的理论模型;详细论述了菲涅耳公式,并对s光和p光的反射率折射率分量进行了对比分析。以本文设计的基于光纤传感的溶液浓度测量系统为基础,引入“压差比”的概念,从理论上推导得出了液体折射率与压差比的对应关系。然后,提出了基于光纤传感的溶液浓度测量系统的总体设计方案,并详细介绍了关键元器件的选型和工艺流程的设计。在光学系统的实际测量中,存在一些影响测量精度的因素,比如光源的不稳定因素、光纤耦合的损耗、光电转换过程中的电路噪声等,会影响液体折射率的测量结果。为了消除这些影响因素的不良影响,在本系统中添加了关键技术用于优化测量。再次,介绍的是溶液浓度测量系统信息处理部分的开发,从数据采集、数据处理、数据传输这三个方面进行了阐述,描述了需要传输的数据,并对其进行技术选型和方案讨论。最后,对本系统进行了仿真和实验,通过实验结果和理论结果的对比分析,证明了本系统的可行性和准确性,总结和展望了溶液浓度测量系统运用在工业生产中的应用和前景。
[Abstract]:Concentration is an important characteristic parameter used to characterize the liquid properties of medium in daily life and industrial production. It is necessary to measure the concentration or refractive index of the solution accurately in many fields, such as basic research, chemical industry, medical diagnosis, food manufacture, environmental protection and so on. At present, there are many methods to measure the concentration. The main physical experimental methods are the specific gravity method, the optical methods are diffraction grating method, the Young's interferometry method, the grazing surface incidence method and so on. Because the properties of the liquid matter under test are not easily changed by optical methods, it is a popular trend to measure the concentration of the solution by measuring the refractive index of the liquid by the optical method, and then measuring the concentration of the solution by the relationship between the refractive index and the concentration. Compared with chemical method, it is more and more widely used. In particular, in recent years, a large number of new optical methods for measuring liquid refractive index have emerged, such as optical waveguide multimode interferometry, plasmon resonance method, confocal spherical F-P interferometry, and SPR based optical fiber sensing methods. By deducing the relationship between solution concentration and refractive index, the concept of "pressure difference ratio" is introduced, and the optical fiber sensing solution concentration measurement system is developed by using light modulation method to measure solution concentration. This paper covers the theoretical derivation, flow design, key device selection, system design, construction and debugging of the solution concentration measurement system. Firstly, it introduces the background and significance of measuring solution concentration, the common physical experiment method of solution concentration measurement, the research status of sensor at home and abroad, the research status of solution concentration measurement method at home and abroad. Finally, the method of measuring solution concentration by linear polarized light based on polarization-maintaining fiber is determined. Secondly, according to Lorentz's electron theory, Maxwell's relation and Lambert's law, the theoretical model of the linear relationship between the refractive index and the solution in a certain concentration range is established. The Fresnel formula is discussed in detail, and the reflectivity refractive index components of s light and p light are compared and analyzed. Based on the solution concentration measurement system based on optical fiber sensor, the concept of "pressure difference ratio" is introduced, and the corresponding relationship between liquid refractive index and pressure difference ratio is deduced theoretically. Then, the overall design scheme of solution concentration measurement system based on optical fiber sensor is proposed, and the selection of key components and the design of technological process are introduced in detail. In order to eliminate the adverse effects of these factors, key techniques are added to the system to optimize measurement. Thirdly, this paper introduces the development of the information processing part of the solution concentration measurement system. It expounds the data collection, data processing and data transmission, describes the data to be transmitted, and discusses its technical selection and scheme. Finally, the system is simulated and experimented. The feasibility and accuracy of the system are proved by comparing the experimental results with the theoretical results. The application and prospect of the solution concentration measurement system in industrial production are summarized and prospected.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN253

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