摘要
光纤布拉格光栅传感器是目前光纤光栅传感领域的主要研究热点之一,被广泛应用于检测桥梁、大坝等大型建筑的质量安全;监测高速公路车辆的超载超限;检测航空航天器以及潜艇、船舶的结构质量等领域。目前国内外不少部门和研究单位在对物体位移的精确检测方面进行了大量的研究,以光纤光栅技术作为检测的方法就是目前研究方向当中备受瞩目的一种。
目前,大多数光纤布拉格光栅位移传感器在测量物体位移变化时,或多或少都受到周围温度变化的影响,使实验结果和理论值偏差较大。本文主要介绍了光纤布拉格光栅传感信号解调原理,设计了一种基于等悬臂梁调谐和匹配光栅解调技术的光纤布拉格光栅传感信号解调技术方案;推导了光纤光栅对的布拉格波长峰值差与悬臂梁自由端位移之间的关系式,并利用双光纤布拉格光栅和适当尺寸的等悬臂梁进行了实验平台的搭建;本文设计了光学部分的调制解调光路,包括光源部分和耦合部分,在优化的光纤光栅匹配解调法的基础上,针对半导体激光器作为光源的特点作出了调整;设计了光电信号转换及电压信号放大电路,利用ARM-Cortex单片机对信号采集和编程运算,并在液晶屏上实时显示出电压变化。
最后对粘贴其上的两个光纤光栅的反射波长峰值差实现线性调谐,并可对调谐范围、灵敏度等指标进行灵活控制。这样就可以有效的消除环境温度变化对位移传感的影响。并推导出试验中光纤光栅波长变化与悬臂梁自由端位移大小的关系,并进行了数据处理和误差分析。
FBG (Fiber Bragg Grating) sensor is one of the hot pots in the field of fiber grating sensors research. FBG has been widely used for quality and safety detecting in bridges, dams and other large construction, and it has been used for highway vehicle overloading or overspeed monitoring, detecting structural quality of aerospace and submarine areas. Currently many departments and research institutions in nature and abroad carried out a lot of research on displacement detected, and taking the fiber grating technology as a method of measurement is one of the most highest-profile research methods.
At present, the most of the fiber bragg grating displacement sensors for measuring displacement, more or less subjects to the changes of ambient temperature, making the experimental results and theoretical values deviate too much. This paper mainly analysis the principle of fiber Bragg grating sensor signal demodulation, and design a cantilever which tuning and matching based on grating demodulation technique of fiber bragg grating sensor signal demodulation technology programs. This paper derive the relationship between the difference of the peak wavelengths of fiber bragg grating and the cantilever free end displacement. In accordance, using pairs of fiber Bragg grating and an appropriate size to design the cantilever experiment. This paper designed part of the modem optical light path, including the light source and the coupling aspect. Based on the optimized fiber grating demodulation method, this paper uses semiconductor laser as light source and aim at its characteristics and make the necessary adjustment, and then designed the photoelectric signal converter and the voltage signal amplification circuit. Using ARM-Cortex Microcontroller to collect signal figures and program operation, the LCD real-time displays voltage.
Finally, the two fiber grating which paste on the cantilever free end reflect wavelength peak achieves a linear tuning, and it may also make tuning range, sensitivity, and other indicators of flexibility under control. So that It effectively eliminates the effort of the surrounding temperature change on the impact of displacement sensor. It is derived the relationship between the size of FBG wavelength and the displacement of the cantilever free end, and carried out data processing and error analysis.
引文
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