【作者】 江建；

【导师】 饶云江；

【作者基本信息】 重庆大学 ， 光学工程， 2004， 硕士

【摘要】 随着现代测量技术的发展,近二十年来光纤传感器越来越受到人们的重视。与传统的电类传感器相比,光纤传感器具有不受电磁干扰、适用范围广、分辨率高、易复用、体积小、重量轻等显著优点。而光纤Fabry-Perot传感器是技术最成熟、应用最广泛的光纤传感器之一。本文首先将国际上对光纤Fabry-Perot传感器的研究历史和现状作了一个较为详细的综述,发现虽然光纤Fabry-Perot传感器的发展十分迅速,但其也有不足之处。如:一般单个传感器都只能进行单参数测量;信号弱;复用能力不够强等。本课题拟在前人工作的基础上,针对FPI传感器若干不足之处,提出一些全新的解决方法。在详细介绍了光纤Fabry-Perot传感器的发展并提出了研究方向以后,完成了如下工作。I. 分析了FPI传感器信号解调的几种方法:强度解调方法、相位解调方法和频域解调方法。并且指出了它们各自的优点和缺点。II. 详细分析了高频CO2激光脉冲写入的长周期光纤光栅谐振波长与谐振峰幅值的温度特性,并进行了实验验证,证明了高频CO2激光脉冲写入的长周期光纤光栅具有良好的温度传感特性,并且指出其可以应用在紫外光写入长周期光纤光栅所无法应用的高温情况下。在此基础上,首次将该长周期光纤光栅与EFPI集成在同一个石英管中制成LPFG/EFPI集成式温度应变同时测量的传感器,实验结果证明该集成式传感器的温度测量精度为±0.5℃,应变测量精度为±20??。III. 在前人工作的基础上分析了掺铒光纤放大系统的功率传输方程,解释了光放大系统的基本原理。在国内外首次提出了一种大幅度提高EFPI传感器信号强度的新方法,设计出了基于光放大的EFPI传感系统,将EFPI信号强度提高了4个数量级,并获得较高的信噪比,同时并未提高系统的成本。IV. 在国内外首次提出了一种对光纤EFPI传感器的变形——光纤Fizeau传感器进行空间频率复用的新方法。和前人提出的复用方法相比,该方法的优点在于结构简单并且复用潜力较大。我们提出了频分复用十个以上光纤Fizeau应变传感器的方法,利用频域解调算法和多项式插值算法克服了测量精度与分辨率的问题,并进行了初步实验验证,实验表明该传感器复用系统应变测量精度可达±10??,分辨率达到1??。更多还原

【Abstract】 With the development of modern measurement technology, more and more research interests are focused to optical fiber sensors in the past two decades. Compared to conventional electrical sensors, optical fiber sensors offer several outstanding advantages, including immunity to electromagnetic interference, capability of responding to a wide variety of measurands, high resolution, capability of multiplexing, small size and light weight, and resistance to harsh environments. Extrinsic optical fiber Fabry-Perot interferometric sensors (EFPI) is one of the most successful optical fiber sensors in practice. After described the research history and current status of EFPI, it can be seen that optical fiber EFPI sensors exist some limitations, such as, one sensor can only measure one parameter, signal is week, and sensors are hardly multiplexed, etc. Hence, we would find some ways to overcome these limitations.The main work completed is summarized as follows: I. Several ways of demodulating the signal from EFPI sensors: intensity-, phase- and frequency-domain-demodulation are analyzed. In addition, their disadvantages and advantages are also discussed, respectively. II. The temperature characteristics of the resonance wavelength and resonance peak value for the long period fiber grating (LPFG) written by the high frequency CO2 laser pulse is analyzed. Several experiments are carried out to verify that such a LPFG has the good temperature characteristics. On the other hand, it can be used in environment with high temperature which is not possible for the LPFG written by ultraviolet light. It is the first time to integrate the LPFG and EFPI in a quartz tube to make a compact sensor which can measure temperature and strain simultaneously. The experimental results prove that this kind of integrated sensor can achieve a temperature accuracy of ±0.5℃ and a strain accuracy of ±20??. III. The power transmission equation and the basic principle of Erbium-doped fiber (EDF) amplification system is analyzed. It is also the first time that put forward a new method to improve the intensity of EFPI sensor signal. An EFPI sensing system based on optical amplification which can improve the intensity by 104 is designed. A relatively high SNR is achieved while the system cost is not increased. <WP=7>IV. It is still the first time to bring forward a new method of spatial-frequency-multiplexing the optical fiber Fizeau sensors which are designed on the basis of EFPI sensors. Compared with the multiplexing method used in the former time, this method has some advantages, such as simple structure and a great potential. A new method which can multiplex more than ten optical fiber Fizeau strain sensors in the spatial-frequency-domain is put forward. The frequency-domain-demodulation and polynomial value-inserted arithmetic are used to achieve high accuracy and resolution. The experimental results show that this kind of multiplexed sensors system can achieve the strain measuring accuracy of ±20?? with the resolution of 1??.更多还原