【作者】 陈雨森；

【导师】 陈伟民；

【作者基本信息】 重庆大学 ， 仪器科学与技术， 2003， 硕士

【摘要】 光纤法珀应变传感是80年代末发展起来的一种新型的应变测量技术，具有结构简单、温漂和时漂小等优点，非常适合于智能结构尤其是大型设施的长期在线应变监测，目前已经成为国外应变传感技术研究的重点之一。对于光纤法珀应变传感器系统，应变信息的解调算法是保证其测量结果准确的关键技术之一，而多传感器复用则能降低其应用的成本，是保证其大规模实际应用的关键所在。本课题对相位型光纤珐珀应变传感系统的解调算法和复用技术作了深入研究。 论文首先阐述了光纤法珀应变传感器的测量原理，分析了实际光源光谱的非均匀分布、波长量化和传感器输出信号中的噪声等对波长域的条纹峰值解调算法的应变测量结果的影响，深入分析了条纹峰值解调算法的局限性。 接着，将低精细度法珀传感器的干涉近似为双光束干涉，根据傅立叶变换的原理，提出了对传感器输出光强分布进行傅立叶变换、从频域直接求取腔长的方法；并讨论了在实际高斯分布光源的条件下，保证傅立叶变换不发生叠级现象对传感器腔长的限制条件。 分析了离散傅立叶(DFT)算法存在的栅栏效应及其对测量结果的影响，提出了通过数据补零和频谱数据高斯插值来降低栅栏效应影响、提高计算精度的方法；讨论了抽样密度变化对栅栏效应及计算精度的影响，并作了仿真计算。 针对实际光强信号在波长域均匀采样，而在频率域非均匀采样的特点，讨论了傅立叶变换的变形——离散腔长变换(DGT)算法。采用黄金分割快速搜索法减小计算量、提高计算速度。 然后，在光强函数的傅立叶变换域，讨论了传感器的复用问题。重点针对并联复用，分析了影响系统复用能力的三个因素——传感器输出信号的频率分辨率、传感器的腔长变化范围和传感器腔长所能达到的最大值，得出了传感器复用的这几个关键参数与系统复用能力之间的关系。 最后，用光纤法珀应变传感系统对混凝土的膨胀系数、弹性模量等特性参数进行了测试；利用等强度梁，对峰值解调、DFT、DGT三种算法进行了对比试验；针对传感器复用的特点，进行了三类复用试验，证明了频分复用解调算法的可行性。更多还原

【Abstract】 The fiber optic Fabry-Perot strain sensing is a new strain measurement invented at the end of 1980.It has become a hot point in the area of "smart structure" in foreign countries since it has the advantage of simple structure and low sensitivity towards temperature. For a fiber optic Fabry-Perot strain sensing system, algorithms used to demodulate the strain information contained in the output of the sensor is the key technology, while the multiplex is the technique used to lower its cost. The thesis is to study the demodulation algorithms and multiplex technology of the phase modulated Fabry-Perot sensor. The main points of the thesis are as follows:1. At the beginning of this thesis, the principle of fiber Fabry-Perot strain sensor is presented briefly, and the influence on the results of the peak-to-peak algorithm, brought by the spectrum distribution of light source, wavelength quantification or the noise in the output of the Fabry-Perot sensor is investigated. The limitation of the peak-to-peak algorithm is pointed out.2. The output of the low finesse Fabry-Perot sensor is approximated as two-beam interferogram. The DFT (Discrete Fourier Transform) method is use to demodulate the gap length of the low finesse Fabry-Perot sensor.3. The accuracy of the results of DFT algorithm is analyzed. Zero-padding on the output data of the Fabry-Perot sensor and Gauss interpolation on their DFT frequency domain can be use to improve the accuracy.4. As the spectrometer sample the output signal of the Fabry-Perot sensor uniformly in wavelength domain, so not uniformly in frequency domain, the DGT algorithm is put forward. A peak search method named golden search rule is applied to reduce the computation intensity.5. Multiplexing technology of fiber Fabry-Perot strain sensor is studied. The frequency domain algorithms are adopted for demodulating sensors connected in parallel. The capability of this multiplexing method is analyzed.6. Experiments are carried out to demonstrate the validity of algorithm improvement and Multiplexing technology.更多还原