【作者】 杨华勇；

【导师】 吕海宝；

【作者基本信息】 国防科学技术大学 ， 测试计量技术及仪器， 2002， 博士

【摘要】 作为光纤传感领域中重要的一族，反射式强度型光纤传感器(简称RIM-FOS)以其结构简单、性能可靠、设计灵活、价格低廉等优点引起了广泛关注。本文在反射光的分布、RIM-FOS的数学模型、强度补偿的理论与方法、传感器特性的仿真与测试、以及可用于传感器辅助设计和制作的计算机仿真测试系统等诸多方面进行了较为系统深入的研究。论文的主要研究内容包括： 1．参考几何法建立的光纤对光强调制函数，首次引入反射面的倾斜因子以及形状因子，建立了相应的数学模型。然后，采用数值仿真的方法系统地研究了多模光纤参数(包括光纤对轴间距、光纤芯径和光纤数值孔径)、反射面倾斜因子以及形状因子对RIM-FOS强度调制特性的影响规律。 2．引入了Beckmann关于随机粗糙表面光散射理论的相关研究结论，基于衍射分析法建立了准高斯光经过反射面后的反射光分布模型。 3．根据所得到的准高斯反射光分布模型，建立了通用的三光纤传感器的强度调制函数。同时，采用“改进的平均间距法”建立了随机型光纤束的数学模型。此外，还对同轴型、双束型、双圈型和同轴随机型光纤束的调制函数进行了详细地推导，得到了具有系统性和关联性的光纤束强度调制函数。然后，仿真比较了各种结构的RIM-FOS的理论特性。 4．用能量流分析法推导了用分光镜分光进行强度补偿的分光比计算公式，详细讨论了入射光的强度不变而偏振方向变化以及二者同时变化对分光比的影响。采用模拟实验验证了分光镜分光中出现反向涨落的现象，提出了具体的解决办法。 5．提出了一种带随机型分光端的“Π”型光纤束分光补偿结构，并与分光镜分光补偿的强度补偿效果进行了实验比较。同时，首次从纯数学的角度分析了光束方向漂移对中孔光电池、半圆光电池以及“Π”型光纤束分光补偿精度的影响。此外，还提出并实验研究了“Π型光纤束分光+神经网络”的强度补偿法。 6．提出了用计算机仿真测试系统辅助RIM-FOS设计及制造的思想，并首次提出了RIM-FOS的最佳设计制作流程。 7．综合采用了一些关键技术，首次设计了一套能够完成RIM-FOS特性仿真和特性测试的计算机仿真测试系统。同时，还提出了归一化特性曲线的参数化描述方法。 8．设计若干典型实验检验了仿真测试系统的性能。结果表明，该系统不但可完成RIM-FOS特性仿真和特性测试功能，而且还可以开机即测且不受环境光干扰和光源功率波动的影响，测试稳定性好，重复性较高。更多还原

【Abstract】 As an important member of fiber optic sensors,the reflective intensity modulated fiber optic sensor (ab. RIM-FOS) has won widely attention in the past forty years,because of its simple configuration,low cost,good reliability and flexibility. It has also been widely used in many industrial measuring situations such as displacement sensor in vibration measurement,as proximity sensor in robotics and automation control,as the readout element in a pressure sensor,etc. In this dissertation,several key problems are studied systematically,which include the reflective light field distribution,the mathematical models of RIM-FOS,corresponding theories and methods about intensity compensation,simulation and testing on the sensor property,as well as the computer simulation and testing system used to help sensor design. The main research concerns on the following lists.1. Firstly,the mathematical model of fiber pair with the factors of reflector shape and inclination is established. Then,the numerical simulation is fulfilled,along with a series of rules of the influence on intensity modulation property caused by multimode fiber parameters,the factors of reflector shape and inclination.2. The reflective light filed distribution is studied in great detail with diffraction approach,which is based on the quasi-Gaussian beam model of the light emitted from the multimode transmitting fiber and conclusions drawn by Beckmann on the scattering light from random rough reflector.3. Then,the mathematical models corresponding to the tri-fiber sensors and six types of fiber bundle sensors are established with the aid of fiber pair model. In addition,simulation research is carried out to obtain their theoretical properties.4. The formula to calculate the light splitting ratio of intensity compensation with light splitter is derived out. Two kinds of circumstances are discussed in detail,the one is laser polarization changing while the intensity keeping stable,and the other is the intensity changing with the polarization. Experiment is completed to verify the theoretical analysis and the resolvent is proposed as well.5. A new kind of fiber structure with random typed light splitting end is put forward,which is called FI typed fiber bundle and can achieve the intensity compensation. The comparison between the two compensation approaches is finished by experiments. The influence on intensity compensation accuracy corresponding to three approachesinduced by the beam direction shift is analyzed in pure mathematic way. Additionally,a novel compensation method with the neural network is studied in addition.6. The idea to aid the RJM-FOS design and fabrication with a computer simulation and testing system is brought out for the first time,as well as the optimum flow chart of sensor design and fabrication.7. The computer simulation and testing system is designed and realized with many kinds of key techniques adopted. It can carry out the functions of property simulation and testing of RJM-FOS. Parametric representation of the normalized property curve is studied.8. A series of representative experiments are planned and fulfilled to inspection the performance of the system. Results show that not only most types of RIM-FOS can be simulated by the simulation and testing system,but also any kind of which can be tested automatically. Also the system can work as soon as power on,while free of the disturbance of environment and power fluctuation of the light source.更多还原