基于反射法的光纤位移 振动传感器优化设计

采用非相干光作为光源,以平面镜为反射面,对光纤位移 振动传感器的性能进行研究。推导出光纤输出功率与测量距离的解析表达式,并详细探讨了不同光纤半径、光纤数值孔径、发射光纤和接收光纤间距、发射光纤和接收光纤轴线夹角下输出功率比与测量距离之间的内禀关系。仿真结果表明:光纤半径越小,光纤间距越大,可以测试的距离范围越小;光纤数值孔径、光纤轴线夹角越小,可以测试的距离范围越小。通过分析不同情况下,输出功率比随测量距离变化的关系,可以在实际工程应用中根据测量需要选择设计合适的传感器。此外,还对测量误差进行了分析,得到光纤轴线夹角越小,测量距离的范围越大,误差率越小,当光纤轴线夹角为0.25时,误差率约为1%。     

光纤外差干涉位移传感器性能的提高

利用半导体激光器 (LD)、光隔离器、光纤定向耦合器、自聚焦透镜等组成双路光纤斐索型干涉仪。采用三角波电流调制 ,上、下边沿拍频信号差动鉴相的方法 ,提高了测量灵敏度和位移响应速度 ,增大了测量范围 ;利用辅助干涉仪检测系统的相位漂移 ,并对LD发光波长进行反馈控制 ,提高了系统的稳定性 ,实现了大测量范围、高分辨率、高精度位移测量。     

基于腐蚀光纤的温度及葡萄糖溶液浓度传感器

提出并制备了一种基于本征倏逝波原理的温度及葡萄糖溶液浓度传感器.通过研究腐蚀包层厚度与透射光谱之间的关系,确定较为合适的腐蚀厚度.将标准单模光纤包层腐蚀至2.4μm,利用光纤倏逝波对外界介质变化敏感的原理,通过测量输出光功率的变化量实现温度及葡萄糖溶液浓度传感.实验结果表明:传感器在1070℃的温度范围内具有9.58×10~(-3) dBm/℃的灵敏度,线性度达到99.36%;在葡萄糖溶液03%的浓度范围内具有0.126dBm/(g/L)的灵敏度,线性度达到97.95%.该传感器的响应时间小于30s,具有操作简便、测量准确度高、重复性好、适用范围广等优点,具备良好的应用价值.     

光纤瞬态高温传感器及动态测试系统

为了解决特殊环境下的瞬态高温测量, 设计了一种基于黑体辐射的光纤高温传感器及动态测试系统。根据辐射测温的基本原理, 结合光纤传感技术, 采用了“接触-非接触”测量方法和光纤光栅窄带滤波技术, 提高了测量精度, 减小了背景光的影响。由于瞬态温度随时间变化快, 动态误差大, 探索了一种利用大功率高频CO2激光器作为激励源, 用激光脉冲加热被校传感器。用测得的温度信号对被校传感器进行可溯源高温动态校准的新方案。实验结果表明, 系统测温范围为800～2000 ℃, 并具有精度高, 响应快, 抗电磁干扰, 性能稳定的特点, 解决了热电偶响应速度慢, 寿命短的缺陷, 为冶金、石油、化工、武器研制等领域的瞬态高温测量提供了一种新的测试手段。     

激光调频光纤位移传感器多路复用技术的研究

叙述了运用半导体激光器连续波调频外差干涉和频域多路复用原理，研究了光纤位移传感器多路复用技术。已研制成的分频与分幅相结合四路复用光纤位移传感器，可同时进行对多点、多维位移和多种物理量的测量，各路位移测量范围大于１ｍｍ，测量精度优于０．１μｍ及位移分辨率为０．０１μｍ。     

Modeling and simulation of polarization errors in Sagnac fiber optic current sensor

Sagnac fiber optic current sensor (S-FOCS) is a kind of optical interferometer based on Sagnac structure, optical polarization states of sensing light wave in Sagnac fiber optic current sensor are limited. However, several factors induce optical polarization error, and non-ideal polarized light waves cause the interference signal crosstalk in sensor, including polarizer, quarter-wave retarder, splice angular, birefringence and so on. With these errors, linearly polarized light wave in PM fiber and circularly polarized light wave in sensing fiber become elliptically polarized light wave, then, nonreciprocal phase shift induced by magnetic field of the current is interrupted by wrong polarization state. To clarify characteristics of optical polarization error in fiber optic current sensor, we analyze the evolution process of random optical polarization state, linear optical polarization state and circular optical polarization state in Sagnac fiber optic current sensor by using Poincare sphere, then, build optical polarization error models by using Jones matrix. Based on models of polarization state in Sagnac fiber optic current sensor, we investigate the influence of several main error factors on optical polarization error characteristics theoretically, including extinction ratio in polarizer, phase delay in quarter-wave retarder, splice angular between quarter-wave retarder and polarization maintaining fiber. Finally, we simulate and quantify nonreciprocal phase shift to be detected in fiber optic current sensor related with optical polarization errors. In the end, we demonstrate S-FOCS in test. The results show that transfer matrix errors are induced by inaccurate polarization properties during polarization state conversion, then, the stability and accuracy of the S-FOCS are affected, and it is important to control the polarization properties at each step of the polarization state conversion precisely.     

原油含水率测量的光学计量仪

油井含水率是油田开发过程中的一个重要指标。光纤传感器具有体积小、重量轻、抗干扰能力强、实时、高效、准确等优点,将其应用于石油测井,有利于提高勘探效率。介绍测井应用中原油含水率计量仪的结构,分析了光纤传感器对混合液体含水率测量的基本原理。激光在弯曲光纤中的传输效率随外界混合介质折射率的变化而改变,根据光纤输出光功率的大小可以测量外界混合介质的组成成分。通过数值模拟,给出了光纤传感器中光束强度随混合液体含水率的变化现象,计算得到混合液体中含水率测量结果。结果表明,光纤传感器计量仪能实现0%～100%含水量的连续测量。最后基于数值模拟结果讨论了系统设计中的注意事项。     

基于阵列波导光栅的边缘滤波温度解调系统

为克服传统阵列波导光栅解调系统体积大、价格昂贵等问题,提出了以窄带光源为输入光源,采用边缘滤波和阵列波导光栅相结合的解调方案,实现对增敏封装后的光纤光栅温度传感器进行温度解调实验。以窄带光源作为输入,通过边缘滤波的方法使得温度传感器反射谱的中心波长偏移程度与解调光路输出光强的变化相对应,利用阵列波导光栅的波分复用实现多传感器同时测量,实现了多传感器多通道的分布式测量,实验结果表明:解调系统的波长解调范围为1 545.30 nm～1 560.50 nm,对35 ℃～42 ℃的温度范围进行检测,波长解调精度为±5.34 pm,温度测量误差可达±0.1 ℃。     

光导纤维在载荷测量及角位移测量中的应用

介绍了力学量中载荷和角位移的测量传感器。其方法是利用光导纤维作为传感器主要元件,被测载荷使弹性元件变形,使光纤端面间光的耦合效率发生变化,通过测量光通量的变化而测知载何和角位移的大小。在载荷测量中特殊布置光纤的位置,通过电路对信号的差分处理能达到提高传感器线性度的目的。最后的传感器输出结果其非线性大为减小。角位移的测试中,这种角位移光纤传感器灵敏度高,分辨率小,适合于扭转试件的微小角位移测量。这类光纤传感器用于力学量测试可弥补一些传统测量方法的不足。     

基于模场自积增强检测的光纤声光旋转传感器

介绍了一种应变不敏感的基于模场自积增强检测的光纤声光旋转传感器.通过调节加载到光纤声致光栅上的微波频率能使双模光纤输出高纯度LP_(11)模式.采用自积增强算法显著提高传感分辨比例,改善探测速度,实现对环境旋转角度变化的动态监测.传感器在0°—180°的测量范围内,角度最大测量误差范围小于11%;在轴向应变为100—1500με之间对应变不敏感.     

二维复用半导体激光器线性调频光纤位移传感器的研究

利用半导体激光器线性调频外差干涉原理和频域多路复用原理,研究了光纤位移传感器多路复用技术,制作了两路复用光纤位移传感器,研究和解决了多路复用时信号串话问题.实验证明,各路之间串话引起的误差小于±0.02μm,每路测量误差小于±0.05μm.     

Design of an optical fiber sensor for linear thermal expansion measurement

Design and operation of an optical fiber device for temperature sensing and thermal expansion measurement are reported. The modulated intensity has been measured by using a pair of 450 μm core fiber, one acting as the source and the other one as receiving fiber. In this design, the light intensity modulation is based on the relative motion of the optical fibers and a reflective coated lens. By using displacement calibration data for this sensor, the linear thermal expansion of the aluminum rod is determined. This sensor shows an average sensitivity of about 11.3 mV/°C for temperature detection and 7 μm/°C for thermal expansion detection. Device resolution for a linear expansion measurement is about 3 μm for a dynamic range of 600 μm corresponding to a temperature change of 100°C. The measured linear expansion results are checked against the expected theoretical ones and an agreement within ±2 μm is noticed. The operation of this sensor was also compared with other types and some advantages are observed, which verify the capability of this design for such precise measurements.     

实现微位移测量的非本征法布里-珀罗干涉型光纤传感器

从光纤耦合和多光束干涉的原理出发,建立了非本征型法布里_珀罗干涉仪光纤传感器的理论模型,得到了用光谱法进行绝对距离测量的公式。设计出了传感器探头的结构,并搭建了系统。用LED作为宽带光源所得到的反射光谱可用于实际样品的微位移测量。实验结果表明,该传感器理论模型的数值模拟结果与实验结果是一致的。对实验数据进行了误差分析,所得到的测量精度可达到1μm。     

激光非接触曲面面形传感器

提出一种用于空间自由曲面测量的激光非接触曲面面形传感器。该传感器结构简单，在光学原理上传感器的输出量与被测量成线性关系，接收物镜绕系统光轴３６０°接收目标面的漫射光，目标面的倾斜产生的影响很小，解决了困扰空间自由曲面测量中阴影效应、倾斜等问题。该传感器的测量范围为４ｍｍ，分辨率为２μｍ，当目标面（漫反射面和金属等镜面反射面）倾斜角为±８５°时，仍能保证２０μｍ的测量精度。     

光纤传感器位移和转速测量研究

介绍光纤传感器的测量原理,并对位移和转速测量进行研究,利用matlab软件对位移测量结果进行曲线拟合,且将光纤传感器和电涡流传感器的转速测量结果进行比较,最后得出利用光纤传感器进行测量具有电路结构简单、精度高、光路弯曲等优点。     

反射式光学电压互感器光路建模及偏振误差分析

光路系统的偏振误差极大地制约着准互易反射式光学电压互感器的准确度.借助琼斯矩阵,建立了分立光学器件及光纤熔接点的传输模型,推导出完整的电压互感器光路系统的数学模型.以此模型为基础,对电压互感器中的偏振误差进行了仿真分析.结果表明：光源偏振度、起偏器消光比及起偏器与相位调制器的对轴角度主要影响系统的检测灵敏度|法拉第准直旋光器的旋光角度、法拉第准直旋光器与BGO晶体的对轴角度误差是主要的偏振误差源,影响系统的测量准确度及稳定性|根据电子式电压互感器IEC60044-7 0.2S级标准,法拉第旋光角度误差应该小于1.6°,旋光器与BGO晶体对轴角度误差小于1.85°.该研究对准互易反射式光学电压互感器光路设计和误差抑制具有一定的参考价值和指导意义.     

A novel distributed optic fiber transduser for landslides monitoring

Unstable slopes have been monitored since the beginning of the last century. Current electro-optic detection technology can achieve automatic monitoring remotely with high safety and includes such methods as time domain reflectometry, optical time domain reflectometry and Brillouin optical time domain reflectometry. However, these technologies cannot simultaneously meet the requirements of distributed sensing, high initial measurement accuracy, large sliding distance and high dynamic range. Based on the space frame theory of reinforced concrete beams, this study presents an innovative design for a distributed optic fiber sensor: a novel transduser with a bowknot. Using the optic fiber microbending loss mechanism and optical time domain reflectometry technology, bending and shear tests based on the combined fiber sensor are conducted, and the vertical displacement of midspan, optical fiber sliding distance and loss data under three different spans are collected. Feasibility study and economic analysis of the transduser used for landslide monitoring are also presented. The results show that the maximum sliding distance of our transduser is 21.8, 26.5 and 30.6 mm with corresponding initial accuracies of 1.2, 2.3 and 3.3 mm, and the dynamic ranges are 0-20.6, 0-23.2 and 0-27.3 mm. The cost of the transduser is economical at $0.15/m, which demonstrates promising economic application, high monitoring effectiveness and stability in monitoring civil works, such as slope, dam and tunnel construction and measurement.     

纳弧度分辨力角位移传感器及平均灵敏度标定

给出了基于六次临界反射棱镜的精密角位移传感器,采用的是差动式结构。实验结果表明,传感器灵敏度高,量程为500μrad,具有5nrad的分辨力。提出了适合于小量程角位移传感器的平均灵敏度的标定方法,可以快速标定平均灵敏度,降低标定过程中标定系统及传感器自身漂移对标定精度的影响。     

切线位移法测量微小角度偏转

叙述了将光电传感器的光轴相对固联于地理坐标系的转轴作切线运动并利用其切线位移模拟小角度偏转的方法。根据两轴初始零位对准值及切线位移量,由光电传感器的输出和所对应的角度偏移关系,获取光电传感器光轴的微小角度偏转量。该方法是一种简单有效的小角度偏移光电检测方法,可实现对微小角度偏移量的精密测量和实时读取,角度测量范围:±15°;测角精度:1″。     

激光位移传感器传感探头微小型光学系统设计

光斑质量直接影响激光位移传感器测量的精度。为了提高激光位移传感器传感探头光学系统的成像质量,设计了传感探头四片式微小型光学系统。本文在理想成像基础上,分析光束在光学系统中能量传递的变化规律,对比光电探测器的感光能力,利用光学设计软件(ZEMAX)实现了激光位移传感器传感探头微小型光学系统的设计。通过理论计算分析,严格控制传感探头孔径光阑的大小,对光学系统进行优化处理,成像最大弥散斑半径低于3. 3μm,空间分辨率120lp/mm以下的传递函数MTF(Modulation Transfer Function)值大于0. 5,光线扇形图的最大像差小于5μm,畸变量低于0. 1859%。该光学系统具有良好的成像效果,可以满足激光位移传感器探测系统对成像系统成像光斑质量的要求,以保证传感器的测量精确度优于5μm。