数事技术与变用
基于温度自补偿原理的光纤布拉格光栅压力传感器
胡魏童杏林
(武汉理工大学光纤传感技术与信息处理教育部重点实验室湖北武汉430070)
应用研究
摘要：本课题研究了温度自补偿对FBG压力传感器的作用。在压增和率拉FBG或温度变化时,FBG周期与反射率会发生变化,从而使光纤光褥中心波长相应漂移。本课题设计的FBG传感器，可以用来分析中心波长添移与水位的对应变化关系,同时消除环境温度与结构热膨账的影响。与通常的 FBG传感器相比,该传感器的结构用来消除温度对压力测量结果的影响,实现温度的自补偿,对于解决温度和压力交叉敏感的问题具有指导性意义。本课题分析了传感原理,进行了温度和压力测试,显示出传感器性能优良,在0-500厘未的水位压力内,精度达5%FS,分辨率1.3cm,重复性误差0.863%，线性误差0.415%
关键调:FBG(光纤布拉格光栅）压力传感器温度自补偿
中图分类号：TP212
文献标识码：A
文章编号：1007-9416(2013)12-0045-04
Abstract:In this paper,we investigated temperature selfcompensation effect applied to a FBG (Fiber Bragg Grating) pressure sensor.By stressing or drawing the optic fiber gratings,or changing the temperature,the period and refleetivity index of opticfiber gratings varies,As a result,the optic fiber gratings reflect center wavelength shifis accordingly.We design a FBG sensor to study and analyze the quantitative relationship between the reflect center wavelength shift and the water level,while eliminating environmental temperature and the thermal expansion of structure interference.Compared with the previous FBG sensor,the structure of the sensor,which is utilized to eliminate the temperature influence on the measurement results of pressure,realize temperature self compensation and has important guiding significance on the solution of the crosssensitivity of pressure and temperature. This paper analyzes the working mechanism of the sensor,the temperature test and presure test.Research showed the good perfommance of the sensor.At the 050cm water level measurement range,accuracy was 5 % FS,1.3cm resolution, linear deviation was 0.415%,and the repeatability deviation was 0.863%.
Key Words:FBG (Fiber Bragg Grating), pressure sensor,Temperature selfcompensation
1INTRODUCTION(引言)
FBG传感器在温度、应力、应变、振动、压力、磁场和电流的检测额域都具有重要的应用。
相对于电类传感器，FBG传感器具有许多优势，如：高稳定性，易于组网并且可以应用于恶劣环境。在压力检测领域，可以通过 FBG传感器中心波长的漂移进行探测，但是环境温度也会对中心波长的漂移产生影响。本课题通过温度自补偿原理消除温度干扰。我们设计了传感器的结构，并且通过温度测试导出温度补偿系数，进面通过压力测试评估传感器性能。
FBG sensor has important application in many fields, such as detection of temperaturell-l,stress,strain/l, vibration l, pressurel, magnetic field*and current, Compared with elec tric sensor,the FBG sensor has many advantages,such as high security ,easy networking and wide application prospect in harsh environments.In the field of detection of pressure, we obtain the pressure by detecting the reflect center wave-length shift of FBG pressure sensor,but the mutative envi-ronmental temperature lead to the reflect center wavelength shift of FBG sensor as well.In this paper,we eliminated temperature interference by the solution method of tempera-ture selfcompensation, We designed the structure of the FBG pressure sensor and derived the temperature compensation coefficient by carrying out the temperature test.Moreover, we carried out the pressure test to analyze the performance of the sensor.
2SENSORPRINCIPLE（传感原理）
The mutative environmental temperature or the axial
strain of FBG causes the Bragg reflect center wavelength shift.When the temperature and the axial strain change at the same time,Bragg reflect center wavelength shift can be given by:
/=+,
(1)
In the equator(1), i, is the reflect center wavelength shift, ig is the reflect center wavelength, is the axial strain. ATis the variation of temperature, K,is the sensitive coeffi cient of strain,and K, is the sensitive coefficient of temperature. 3DESIGNAND ANALYSIS OF STRUCTURE
(传感器结构设计与分析)
3.1 DESIGH OF STRUCTURE(结构设计)(如图1)
In Figure 1,we pasted FBG2 respectively in the end side of the metal tube 1 and the metal tube 2.FBG1 was placed in the metal tubel and pasted only on the center of the metal diaphragm.The metal tube 1 was pasted on the center of the metal diaphragm as well.The metal diaphragm was utilized for loading of water pressure which led to deformation of the metal diaphragm, The strain which was caused by the deformation passed through the metal tube 1 to FBG2. resulting in the reflect center wavelength shift. Therefore,a corresponding pressure value can be calculated by detecting the center reflect wavelength shift. In the metal tube 1,FBGI which was in the natural state was utilized for temperature measurement or temperature compensation of the sensing grating FBG2.
3.2 ANALYSIS OF STRUCTURE(结构分析)(如图2)
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