【作者】 方卉；

【导师】 于清旭；

【作者基本信息】 大连理工大学 ， 光学工程， 2009， 硕士

【摘要】 光纤法布里-珀罗（F-P）传感器作为一种高精度的干涉型光纤传感器,具有结构简单、体积小、灵敏度高、不受电磁干扰、适用于恶劣环境、能够实现远程信号处理和可以复用等优点,具有广泛的工业应用前景。目前,已成功应用于土木工程、油井监测、航天航空、医学及生物等方面。本文对光纤F-P传感器的参数设计、制作和复用技术进行了深入的研究。首先,利用真空镀膜和光纤熔接技术制作出端面镀金膜、插入损耗低的光纤本征法布里-珀罗（IFPI）传感器,详细分析了其温度、应变传感机理,并对其温度、应变传感特性进行了实验研究,为后续的复用研究奠定基础。实验证明,对于相对腔长为357.675um的光纤IFPI传感器,从室温到250℃的温度范围内,相对腔长随温度变化灵敏度为2.42nm/℃;在测量范围400με内,应变灵敏度为0.28nm/με,与理论分析相符。通过优化可设计出合适的IFPI感器腔长来满足实际的温度应变测量灵敏度要求。在实验室已有研究工作的基础上,设计和制作了适用于高温高压环境下的多参量测量的光纤非本征法布里-珀罗（EFPI）传感器。该光纤EFPI传感器是采用CO₂激光热熔接技术制作的,由于不同材料的热膨胀系数不同,分别用多模光纤和玻璃丝制作反射端,优化设计出低温度压力交叉敏感的光纤EFPI压力传感器和高灵敏度的光纤EFPI温度传感器。对于EFPI压力传感器其压力灵敏度为24.8nm/Mpa,对于EFPI温度传感器其温度灵敏度为22.3nm/℃。最后,提出IFPI/EFPI串联复用结构,分析了频分复用的原理并进行数值模拟。首先利用加Hamming窗的FIR带通滤波器对串联叠加信号进行滤波和分离;然后采用交叉相关解调算法分别对两个传感器信号进行解调,并且分析了两个传感器信号串扰的原因,主要是傅里叶变换后两信号旁瓣的影响。利用加Hamming窗技术可以减小这种串扰。实验结果表明,两传感头之间的串扰最小可低至0.1%,能够满足实际应用。更多还原

【Abstract】 As a kind of high-precision interferometric optical fiber sensor, the Fabry-Perot （F-P） interferometric optical fiber sensor has won wide attention for its small size, compact configuration, good reliability and flexibility, immunity to electromagnetic interference, high adaptability in harsh environments, remote signal processing and the possibility of multiplexing. It has been widely used in civil engineering, oil well monitoring, aerospace, medicine and biology. In this dissertation, two types of Fabry-Perot interferometric optical fiber sensors are designed, fabricated and multiplexed. The main research works are outlined as followings:At first, intrinsic Fabry-Perot interferometric（IFPI） fiber sensors of low power loss are fabricated by fused splicing and coating in vacuum, thin gold deposited films used as partial reflectors. They are good candidates for multiplexed sensors networks. Then the mechanism of IFPI optical fiber sensors on the stress and temperature is discussed in detail and the corresponding experiments are carried out. To an IFPI optical fiber sensor with the cavity length of 357.675um, the experimental data indicate that the temperature sensitivity is 2.42nm/℃when the temperature varies from room temperature to 250℃and the stress sensitivity is 0.28 nm/μεwithin the range of 400με. The results, coincided with the theoretical analysis, imply that the IFPI optical fiber sensors can match different measurement conditions by optimizing the cavity length.After that, extrinsic Farby-Perot interferometric（EFPI） optical fiber sensors used for temperature or pressure measurements, are fabricated by using CO₂ laser thermal fusion method. Considering the diverse thermal expansion coefficient of individual material, multi-mode fiber and glass fiber are applied as reflecting fiber of the F-P sensor to design an low temperature and pressure cross-sensitivity EFPI pressure sensor and an EFPI temperature sensor respectively. Benefiting from the novel design, the sensitivity of the EFPI pressure sensor reaches 24.8nm/Mpa and the sensitivity of the EFPI temperature sensor is up to 22.3nm/℃.Finally, the serial frequency division multiplex （FDM） system based on IFPI and EFPI optical fiber sensors are represented. From the discussion of the FDM principle and corresponding simulations, the FIR band pass filter combined with the correlation demodulation fitting to analyze the superposed signal from the IFPI and EFPI sensors. In fact, the Hamming window conduces to suppressing the crosstalk between the two sensors in signal processing. The experimental results show that the crosstalk of the multiplexed system is limited below 0.1%.更多还原