机敏复合材料中损伤探测光纤阵列及其传感信号处理

本文半一种新颖的，结构简单的“城墙”型光纤传感阵列埋置于复合材料结构内，用于探测复合材料结构内由于外部冲击成的损伤等状态参数，对于内埋光纤阵列输出的传感信号，则采用人工神经网络来处理，并给出了Ｋｏｈｏｎｅｎ网仿真结果。     

干涉型光纤传感器的分集消偏振衰落技术的信号处理

对干涉型光纤传感器的分集检测消偏振衰落技术进行了理论分析，提出了将各路信号平方后相加的信号处理方式，使之能实现单元及阵列的实时消偏振衰落信号检测。通过理论计算，可以使干涉信号幅度波动小于4.7dB，并得出三路检偏是分集检测的最简取的结论，通过信号处理电路，能够在信噪比略有降低的情况下消除偏振衰落的影响，实现进一步光纤传感器的消偏振衰落，并设计了用于阵列的分集检测的实现方式。     

机敏复合材料中损伤探测光纤阵列及其传感信号处理

本文将一种新颖的、结构简单的"城墙"型光纤传感阵列埋置于复合材料结构内，用于探测复合材料结构内由于外部冲击造成的损伤等状态参数。对于内埋光纤阵列输出的传感信号，则采用人工神经网络来处理，并给出了Kohonen网仿真结果。     

一种光纤机敏蒙皮系统

在简述作者提出了的种新型的光纤传感阵列及其信号处理的神经网络方法的基础上，给出了一种光纤机敏蒙皮系统的结构及功能，阐述与分析了系统实验的结果。     

用光纤传感器阵列测量动态变量

用光纤传感器阵列测量动态变量Ｊ．Ｎｉｅｗｉｓｃｈ等１．概述分布式光纤传感器或由光纤连接成的光传感器阵列，在大面积、多测量点的监视方面有很大的潜力。定位分辨率可用光时域反射计（ＯＴＤＲ）的原理来表达，这个方法最典型的用途为静态效应（仅随时间作慢变化的测...     

同轴干涉型光纤水听器声压灵敏度特性分析

建立了等效模型对含弹性增敏层的同轴干涉型光纤水听器的声压灵敏度进行了理论研究，分析了探头的结构参数和材料特性对声压灵敏度的影响．分析表明，水听器的声压灵敏度随缠绕光纤长度和芯轴长度的增加而增加，随骨架厚度和增敏层的厚度比例的减小而增大，同时采用杨氏模量和泊松系数小的增敏材料能够提高灵敏度．得到了提高探头声压灵敏度的有效途径，并制作了一系列光纤水听器样品，对理论分析结果进行了实验验证，理论分析结果与实验结果基本吻合．     

光纤水听器频分多路复用研究

本文通过对光纤水听器阵列中频分多路复用（FDM）方案的理论分析及实验研究,探讨了在多光源、多基元条件下信号调制频率以及频率间隔的选择,为以后大型光纤水听器的构阵研究打下基础。     

光纤阵列成像激光雷达系统的设计

简要介绍了光纤阵列成像激光雷达的研究背景、系统优势和发展现状.然后提出了本文设计的雷达系统,并介绍了该系统的工作原理,系统采用光纤阵列前端窗口扫描的方法,避免了光电探测器阵列的制作,同时减少了光电探测器的数量.之后文章对光纤阵列成像激光雷达系统的各部分器件进行分析,包括光纤的选择、光纤阵列的设计和聚焦透镜的分析,并重点讨论了聚焦透镜F值对光纤阵列接收系统的影响,最终得到本系统聚焦透镜F最优值5.47.最后推导了本文光纤阵列成像激光雷达系统的传输效率,给出了传输效率公式.     

反射式光纤传感器光纤对输出特性的数学模型

从反我纤传感器中最基本的光纤对入手，以光度学原理为基础，建立了该传感器在镜反射时的输出特性数学模型。在此模型的基础上，利用计算机给出了光纤传感器输出特性的仿真结果并进一步讨论了输出特性与各参数之间的关系。     

甚多孔径光纤激光相控阵的光束扫描特性研究

甚多孔径光纤激光阵列是构建大功率、高光束质量、等效光学大口径的新兴技术手段之一,而基于相位精密操控实现阵列激光束的共相,乃至快速、灵活的光束偏转是当前光纤激光相控阵技术面向应用的关键。本文将光学相控扫描技术与光纤激光相干合成系统相结合,研究了甚多孔径光纤激光相控阵的光束扫描特性,通过改变准直激光阵列相邻子孔径间的相位差实现了光束扫描。对比分析了19、133、703孔径光纤激光相控阵的远场扫描光束形态分布特征,据此定义并计算了扫描极限范围。该结果为后续开展光纤激光相控阵在长程传输下精确指向控制实验研究提供了理论依据。     

基于干涉解调技术的光纤激光器水声传感系统

分析了基于Michelson干涉解调技术的光纤激光器水声传感的原理,在一段掺铒光纤中写入具有π相移的光纤光栅构成光纤激光器,水声压力作用在激光器上引起激光工作波长的变化;采用基于3×3耦合器的偏振无关的非平衡光纤Michelson干涉仪将激光波长变化转化为干涉仪的相位变化;干涉仪的输出由光电探测器转换后使用DSP进行信号解调.针对3×3耦合器分光比不对称的问题,本文提出利用实时调整幅度的2路干涉信号进行解调的方案,该方案不需要3×3耦合器有严格的分光比,消除了外界环境对解调输出的非线性影响.水声探测实验表明,光纤激光器水声传感系统的声压灵敏度为-166.5 dB(参考值1 rad/μPa),解调结果与水声信号具有良好的线性关系.     

Measurement and analysis of residual stresses in single fiber composite

This paper deals with the thermal residual stress of carbon fiber-reinforced composite, which arises from the different coefficient of thermal expansion (CTE) of constituents during cooling from the processing temperature down to room temperature. It is studied by experiment and theoretical analysis. In experiment, the real-time electrical resistance detection method is applied to measure the carbon fiber electrical resistance, where the single carbon fiber itself is used as internal sensor in composite material. The axial residual strain and also stress is obtained by the relationship between strain and electric resistance based on its electrical property. To explain the experiment data, a 3D theoretical column model with three phases was established to calculate the unit cell stress field by governing equations and boundary conditions. Result shows the experiment data is approximately close to theoretical model; meanwhile, theoretical model gives more detailed stress distribution, which is difficult to measure, in three directions of all phases.     

基于碳纤维复合材料的柔性复合式触觉传感器

分析了碳纤维复合材料的敏感特性,基于该种材料良好的压力/温度敏感特性,设计了一种具备压力和温度同时检测功能的新型柔性复合式触觉传感器。利用2种碳纤维复合材料各自具有的不同压力和温度敏感特性构建了求解压力和温度的数学模型,基于该模型设计并制作了柔性复合式触觉传感器。通过对传感器标定及实验结果的误差分析表明,该传感器设计解决了压力和温度同时检测时存在的交叉干扰问题,实现了传感器的复合式功能。     

光纤模斑传感器应用于在线监控复合材料工艺过程

复合材料的固化有着复杂的内部过程, 传统的工艺条件难以保障产品的质量, 发展智能化的在线监控技术是个有效途径, 在线监控系统需要有先进的传感器。研制了一种新型光纤传感器, 提出通过测量光纤末端近场模斑谱反映光纤埋置周围树脂折射率的变化。给出了利用这种传感器进行复合材料固化监测的实验结果。发现这种光纤传感器的信号能反映固化凝胶点、固化结束点及树脂粘度的最低点, 又由于光纤与复合材料的兼容性好以及装置简单、廉价、可靠性高, 因此可以应用于复合材料固化过程的在线监控系统。     

新型光纤压力传感器

研究了一种新型的光纤压力传感器,并基于理论模型作了相应的优化设计,该传感器由光纤环和Ｃ形弹簧管复合而成、并配有完善的处理电路及微机测控系统,实用性强。     

Sagnac-type fiber-optic array sensor for detection of bulk ultrasonic waves

In this paper, we describe a fiber optic array sensor suitable for detection of bulk ultrasonic waves. This sensor is based on an intrinsic fiber optic Sagnac interferometer. The fiber array is formed by multiple folding of a continuous length of an optical fiber into flat coils. Depending on the orientation of the fiber array with respect to the ultrasonic wave, the proposed sensor can act as a conventional in-phase detector or as a narrowband detector. In the narrowband mode, the center frequency of detection can be tuned by adjusting the spacing of the fiber array elements to be equal to the ultrasonic wavelength of interest. This feature distinguishes this array sensor from conventional hydrophones in which a receiver is typically much smaller than the acoustical wavelength. It is shown that the array sensor provides an enhanced signal-to-noise ratio (SNR) compared with a single element detection scheme. Results are presented for detection of ultrasonic waves in water arising from both piezoelectric and laser ultrasonic sources. Potential areas of application of this sensor include process monitoring, smart structures, bio-medical ultrasound, and chemical sensing.     

Microelectromechanical system pressure sensor integrated onto optical fiber by anodic bonding

Optical microelectromechanical system pressure sensors based on the principle of Fabry-Perot interferometry have been developed and fabricated using the technique of silicon-to-silicon anodic bonding. The pressure sensor is then integrated onto an optical fiber by a novel technique of anodic bonding without use of any adhesives. In this anodic bonding technique we use ultrathin silicon of thickness 10 microm to bond the optical fiber to the sensor head. The ultrathin silicon plays the role of a stress-reducing layer, which helps the bonding of an optical fiber to silicon having conventional wafer thickness. The pressure-sensing membrane is formed by 8 microm thick ultrathin silicon acting as a membrane, thus eliminating the need for bulk silicon etching. The pressure sensor integrated onto an optical fiber is tested for static response, and experimental results indicate degradation in the fringe visibility of the Fabry-Perot interferometer. This effect was mainly due to divergent light rays from the fiber degrading the fringe visibility. This effect is demonstrated in brief by an analytical model.     

保偏微结构光纤光栅 F-P腔折射率传感特性分析

针对提高光纤光栅折射率传感器抗干扰能力以及增加反射率的需求,本文提出了一种基于Fabry-Perot腔的保偏微结构光纤(PM-MOF)布拉格光栅折射率传感器.根据传榆矩阵法和有限元方法,分析了微结构光纤光栅F-P腔中被测物折射率与F-P腔反射谱中两个偏振模谐振波长差的关系,在此基础上讨论了中心孔直径、F-P腔长度等参数对传输特性的影响.研究结果表明,随着空气孔中填充物折射率的增加,保偏微结构光纤光栅F-P腔的两个偏振态的谐振波长差将逐渐减小;F-P腔的干涉作用使反射率较单个光栅有很大提高,便于长距离传输和实时解调;两个偏振模对外界干扰具有相似的响应,因此该传感器具有更强的抗干扰能力.本文研究结果为保偏微结构光纤光栅在折射率传感器及其生物传感器方面的应用提供了理论依据.     

光纤缠绕式应变传感器

研究了一种可用于机敏复合材料与结构状态监测的本征型强度调制光纤应变传感器,它由两根以上多模光纤相互缠绕绞合形成。分析了该传感器的应变传感原理,得到其既能测量拉应变、又能测量压应变的结论。传感器对应变的响应具有良好的线性和重复性,灵敏度高,无迟滞现象。对植入碳纤维/环氧复合材料内的光纤缠绕型应变传感器的实验结果与理论分析一致,表明该传感器是适合于机敏复合材料与结构状态监测的较为理想的光纤传感器。     

Theory of 1-N-way phase-locked resonators with perturbations in the array elements.

The recently proposed 1-N-way resonator based on beam splitting and beam combining effects in rectangular cross-sectional multimode waveguides offers a valuable way in which N low-power laser elements can be combined in a coherent fashion. We develop a theory of such resonators in the presence of perturbations in the N-element array. We demonstrate that despite the presence of perturbations there is only one possible mode of the resonator. The theory is used to provide an understanding of the effects of a number of possible perturbations that could arise as a result of manufacturing processes and operational effects. The results give scaling laws for the design tolerances on array element mirror tilt, array element optical path length control, and the effects of array element malfunction and their need for gain balance.