基于无芯光纤的浓度检测研究.doc

基于无芯光纤的浓度检测研究 摘要: 本文基于溶液浓度和折射率的关系，提出了一种用折射率调制的无芯光纤液体传感器来测量浓度的方法。 首先，本设计介绍了测量液体浓度的历史发展背景，国内外研究现状，分析了几种检测液体浓度的方法，确定了本次设计所用的折射率分析法。其次，由物理光学基础知识推导出浓度折射率关系，再分析我们提出的压差比和折射率的关系。在入射角小于临界角的情况下，此时对被测溶液的浓度没有太大要求，方便实验，并且仿真得出关系曲线。最后，搭建光纤传感系统，仿真单片机信号处理电路，做出相应的实物电路系统。其中光纤传感系统采用双光路的形式，光经过光开关后，一路直接进入光电转换探测器，另外一路通过液体折射后再进入一型号完全一致的光电探测器。双光路系统能有效的减小系统的噪音信号，所以采用压差比的算法，这也是本设计的新颖之处；两路光脉冲信号通过单片机处理电路，在 LCD 分别上显示出高低电平之差，再通过计算得出压差比，由液体浓度和折射率以及压差比的关系，从而求得被测液体的浓度。 关键词：光纤传感器，溶液浓度检测，无芯光纤 Abstract Based on the relationship between solution concentration and refractive index, a method for measuring concentration with a refractive index modulated coreless fiber optic liquid sensor is proposed. First of all, this design describes the history of liquid concentration, development background, research status at home and abroad, analysis of several methods to detect liquid concentration, to determine the design of the refractive index analysis method. Secondly, from the basic knowledge derived from the relationship between the concentration of the refractive index of physical optics, and analysis of the relationship between the pressure ratio and refractive index of our proposed. When the incident angle is less than the critical angle, the concentration of the solution is not required at this time. The experiment is convenient and the relation curve is obtained by simulation. Finally, the optical fiber sensing system is constructed, and the signal processing circuit of the MCU is simulated to make the corresponding physical circuit system. The optical fiber sensing system with double optical path, the light passes through the optical switch, a photoelectric conversion directly into the detector, another way through the liquid refraction before entering a completely consistent type photoelectric detector. The double optical path system can reduce system noise signal effectively, so the pressure difference algorithm, which is the novelty of the design; signal processing through the MCU circuit of two ligh