基于光纤布拉格光栅的实时测温系统的设计论文

河南机电高等专科学校

毕业设计论文

论文题目：基于光纤布拉格光栅的实时测温系统的设计

系 部 专 业 班 级 学生姓名 学 号 指导教师

2012年05月 1 日

河南机电高等专科学校毕业设计/论文

目录

摘要 ....................................................................................................................................................... I Abstract ................................................................................................................................................. II 第1章 绪论 ...................................................................................................................................... 1

引言 .............................................................................................................................................. 1 1.2光纤光栅的诞生极其分类..................................................................................................... 1 1.3光纤光栅传感技术的特点和应用 ......................................................................................... 2

1.3.1 光纤布拉格光栅传感技术的特点 ............................................................................. 2 1.3.2 光纤传感技术在实际中的应用 ................................................................................. 4

第2章 光纤光栅传感理论................................................................................................................. 5

2.1 光纤光栅的基本原理............................................................................................................ 5

2.1.1 光纤光栅的基本光学性能 ......................................................................................... 5 2.1.2 光纤光栅的传感原理................................................................................................. 6 2.2 光纤光栅的传感灵敏度........................................................................................................ 8

2.2.1 应变灵敏度 ................................................................................................................ 8 2．2.2温度灵敏度 .............................................................................................................. 9

第3章 光纤光栅解调方法............................................................................................................... 10

3.1 光纤光栅的解调概念.......................................................................................................... 10 3.2 光纤光纤传感系统解调方法介绍 ...................................................................................... 10

3.2.1光谱仪检测法 ........................................................................................................... 10 3.2.2 非平衡马赫-曾德干涉仪跟踪法 ........................................................................... 11 3.2.3 匹配光栅法 .............................................................................................................. 11 3.2.4 可调谐窄带光源解调法 ......................................................................................... 12 3.2.5 线性边带滤波解调法............................................................................................... 12 3.2.6 可调谐法布里—珀罗腔法 ....................................................................................... 13

第4章 实验系统 .......................................................................................................................... 14

4.1 光纤光栅测温系统的总体架构 .......................................................................................... 14 4.2 光路部分 ............................................................................................................................. 15

4.2.1ASE宽带光源 ............................................................................................................. 15 4.2.2 光纤耦合器 ............................................................................................................ 15 4.3 信号处理电路部分 ............................................................................................................. 16

4.3.1 ADC与DAC电路设计 ............................................................................................... 16 4.3.2 高速数字信号处理电路设计 ................................................................................... 18 4.4 参考光纤光栅的标定.......................................................................................................... 21 4.5 服务器端软件设计 ............................................................................................................. 21 第5章 系统测试 ............................................................................................................................ 25

5.1 测试过程及数据 ................................................................................................................. 25 结论 .................................................................................................................................................... 27 致谢 .................................................................................................................................................... 28 参考文献 ............................................................................................................................................ 29

河南机电高等专科学校毕业设计/论文

摘要

光纤布拉格光栅(FBG)自1978年出现以来,由于其良好的滤波特性和灵敏的温度、应变响应,已经在光纤通信、传感和测量等领域取得了广泛应用。光纤光栅传感器除了具有一般光纤传感器的优点外,其突出特性是:被测信号是波长编码的,并且方便利用时分、波分复用技术实现对多种传感量(应力、温度、强磁场等)的准分布式多点测量。如何对光纤光栅的波长编码信号进行解调是实现光纤光栅传感器应用的关键技术之一。 本文首先概括介绍了光纤光栅的诞生与发展、光纤光栅传感器的原理与应用、光纤布拉格光栅传感解调的国内外现状。分析了光纤光栅温度和应变传感机理,并讨论了光纤光栅温度——应变交叉敏感问题。接着,对目前国内外已经研究过的光纤光栅传感系统波长解调方法进行了简单的归纳和分析。 本文对光纤光栅波长的解调方法是基于F-P滤波器解调的光纤光栅测温系统。本系统主要包括光路部分、信号处理部分、恒温控制部分、通信部分、本地显示和报警输出部分和服务器通信管理软件等。根据光纤光栅的中心波长的计算方法设计了相应的硬件电路,设计了本系统的相关软件程序,对光纤光栅的波长进行解调,并且转换成温度显示在液晶上面,或者通过RS232串口或以太网接口和计算机相连,将测量的结果由计算机显示出来。 本系统的高速数字信号处理电路部分采用的高性能浮点DSP处理芯片,实现采集数据的实时运算处理,将处理后的结果信息通过串口发送至控制模块,再通过GPIO接口对控制模块等相关模块进行通信。 系统搭建完成后,进行了对系统性能的测试,检验系统测量温度的准确度,其中包含两个方面:一是对系统解调光栅波长准确度的验证;二是对系统温度定标准确度的验证。经检验,本文得出的实验结果有一定的实用价值。对FBG传感器的使用和推广具有重要的实际意义。

关键字：布拉格光栅；波长编码；、F-P滤波器；DSP；测温

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河南机电高等专科学校毕业设计/论文

Abstract

Since fiber Bragg grating came out in 1978,it has been widely applied because of its good filtering character and sensitive to temperature and strain response in the field of fiber communication ,sensor ,measure ,etc. Fiber Bragg grating sensors have the character which the common fiber sensors have. Furthermore their prominent character is that the measuring signal is wavelength encoding , they achieve avriety of sensing by using quasi-distributed multi-point measurement conveniently. How to demodulate the wavelength encoding signal is one of the key technologies for the application of fiber grating sensors.

Firstly, the naissance and development of fiber grating, the principle and application of fiber grating sensors, the actuality of wavelength demodulation At home and abroad were introduced in the paper. It analyzed the fiber grating temperature and strain sensing mechanism and discusses the cross sensitivity of fiber grating temperature-strain . Then ,it carried on the simple conclusion and analysis about fiber bragg grating sensor wavelength demodulation system which has been researched by domestic and foreign .

The method of the fiber grating wavelength demodulation is fiber bragg grating temperature measurement system based on F-P filter .Optical part ,signal processing, temperature control part, local display , alarm output and server communication management software and so on were included in this system .The hardware and software program were designed according to the center wavelength of fiber grating, the tesults of FBG wavelength demodulation were displayed on the LCD or were displayed by the computer through the RS232 serial port or Ethernet interface connected the system to the computer.

The floating point DSP processing with high-performance chip was used in the high-speed digital signal processing, and address the results of the information which was processed sent to the control module through the serial port, and communicate with control module and other related modules through the GPIO interface.

We tested the performance of the system ,testing system, the accuracy of measuring temperature after the system built, which includes two aspects: First ,the verification of accuracy of grating wavelength demodulated by system; second, the verification of accuracy of system temperature calibration .Upon examination, This experinmental results obtained by this paper have some practical value.

Keywords: Bragg grating; wavelength encoding; F-P filter; temperature

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