基于FBG的输电线路温度解调系统

温度监测是输电线路覆冰监测中的重要组成部分。本文研制出基于单片机的低成本高分辨率高精度光纤Bragg光栅(FBG)温度解调系统。该系统利用可调谐F-P滤波器法对温度传感器反射光谱进行波长解调。为降低F-P腔腔长漂移和压电陶瓷非线性的影响,采用3根FBG作为参考光纤光栅,对波长-温度曲线进行二次拟合求解。试验结果表明,该解调系统分辨率达1.4pm,精度达1.2℃,具有广泛实用性。     

Bragg光纤光栅法布里-珀罗传感器应变测量的研究

文章提出了一种对静态应变进行高分辨率测量的新方法。该方法是将 Bragg 光纤光栅(FBG)与全光纤法布里-珀罗传感器(FFPI)组合使用,利用 FBG 的反射波长漂移特性来测量干涉条纹的数目,利用 FFPI 和伪外差解调法对小数条纹进行解调,实现高分辨率的测量。通过实验测定,该系统对静态应变测量的分辨率达到了33nε。     

基于倾斜光纤光栅的传感解调技术

该文设计了一种基于倾斜光纤光栅（tilted fiber Bragg grating,TFBG）的不受温度影响的光纤布拉格光栅（fiber Brag ggrating,FBG）应变解调系统．将倾斜光纤光栅用作边沿痣波器,当周围环境温度变化时,利用倾斜光纤光栅纤芯模与包层模的温度特性与普通光纤布拉格光栅相同这一特点,无需另加温度补偿,就可以实现FBG应变传感的动态解调,消除温度噪声对应变信号的影响．由实验可知,当温度在25℃到39℃范围变化时,解调系统的性能基本不发生改变,解调范围达到6nm．     

光纤Bragg光栅用于高频应变测试的研究

提出了一种传感部分采用光纤Bragg光栅(Fiber Bragg grating,FBG)传感器的高频应变测试新方法.设计并构建了基于非平衡马赫-曾德(Mach-Zehnder)干涉仪的高频解调系统.完整的测试系统由FBG传感器、高频应变产生装置和解调系统三部分组成.所产生的应变信号的频率可以通过专门的实验装置来控制,这是一种广泛用于测试材料机械性能的变形分离式霍布金逊压杆(Split Hopkinson Pressure Bar,SHPB)实验装置,应变持续的时间根据与撞击弹性等径的冲锤长度计算.借助高频振动信号研究了测试系统可测信号的频率范围.给出了振动和冲击实验结果,并进行了讨论.所设计的系统可以实时测试动态应变的幅值,实验结果表明,该系统对频率为8kHz以下的信号具有好的响应.     

基于FPGA的多通道高速光纤光栅解调系统

研发了一种基于波长扫描光源和嵌入式解调的多通道高速光纤布拉格光栅解调系统。该系统采用半导体光放大器(SOA)结合可调谐F-P滤波器产生频率为1 kHz的稳定波长扫描光。通过使用对称三角波技术和快速FPGA解调算法,系统最终能够同时实现16个通道以及2 kHz的解调速率,测量范围80 nm。     

光纤Bragg光栅用于动态应变测试的研究进展

应变测量是光纤光栅的主要应用之一。概述了光纤Bragg光栅（FBG）在不同时期和领域用于动态应 变测试的研究进展;阐述了传感头、信号的解调方法和工程应用;评述了基于光纤Bragg光栅的动态应变测试方 法和解调技术;比较了各自的优缺点和目前所能达到的测试范围     

天津大学光纤传感技术研究部分最新进展

本文介绍了天津大学在光纤传感技术研究领域的最新进展.主要为:基于白光干涉实现了非本征光纤法珀和FBG并行解调,法珀腔长测量误差0.81 μm,FBG波长测量误差14 pm;基于光纤有源内腔结构夹现了乙炔气体传感,灵敏度优于100ppm;基于保偏光纤实现了分布式传感,灵敏度可达6 cm;基于边缘滤波器开发了光纤光栅解调仪,波长分辨力可达1.2pm,扫描速率超过200kHz;采用全光纤OCT技术实现了牙齿模型的二维、三维扫描;实现了光纤陀螺光纤环的温度、振动等动态特性检测.     

利用WDM光纤耦合器的光纤光栅传感解调技术

根据 WDM 光纤耦合器波长解调方案的工作原理、偏振特性以及影响系统波长分辨力的因素,提出一种改进的利用 WDM 光纤耦合器的光纤光栅传感解调技术。该技术在原技术的基础上,采用偏振控制器控制入射光偏振状态,提高了解调的精度和稳定性。对 WDM 光纤耦合器的多次波长扫描结果表明,采用偏振控制器后,其波长误差可减小到 5pm 左右。实验采用 1540/1560nm的 WDM 光纤耦合器对单点光纤光栅应变传感器进行静态解调,结果表明:按此技术开发的解调系统具有 0.01nm 波长分辨力和 10nm 的波长线性解调范围。     

基于可调光纤F—P滤波器解调的分布式光纤光栅传感系统

提出并实现了一种可满足工程实用要求的波分复用光纤光栅传感网络解决方案，系统通过可调谐光纤F-P滤波器的连续扫描实现波长信号的解调，该传感系统扫描带宽50nm，单点工作带宽5nm，对一般应用系统每根单纤可设20-30个点，系统最高扫描频率200Hz，分辨率5pm(约5με或0．5℃)。     

F-P光纤应力传感器研制

分析了F-P光纤应力传感器工作原理,提出了F-P光纤应力传感器的数学模型,设计了F-P光纤应力传感器弹性体结构、光电转换系统.F-P光纤应力传感器光源电路设计采用APC电路.APC电路由两个运算放大器和晶体管以及外围电路组成,采用背向光反馈自动偏置控制方式,即用半导体激光器组件中的PD光电二极管监测LD背向输出的光功率.对F-P光纤应力传感器进行了静态特性标定试验,试验结果表明,该传感器具有较高的测量精度,能够满足工程测量要求.     

Distributed strain measurement in a rectangular plate using an array of optical fiber sensors

Single mode optical fiber waveguide has been used to determine the two-dimensional strain distribution on a simply supported rectangular plate. Each of the fifty individual fibers in the rectangular grid array attached to one surface of the plate yields a measurement of the strain integrated along the length of that fiber on the specimen. By using similar sensor information from all of the fibers, both the functional form and the amplitude of the distribution may be determined. Limits on the dynamic range and spatial resolution are indicated. Applications in the measurement of internal strain and the monitoring of physically small critical-structural components are suggested.     

Dynamic two-axis curvature measurement using multicore fiber Bragg gratings interrogated by arrayed waveguide gratings

We describe the use of arrayed waveguide gratings (AWGs) in the interrogation of fiber Bragg gratings (FBGs) for dynamic strain measurement. The ratiometric AWG output was calibrated in a static deflection experiment over a +/-200 microepsilon range. Dynamic strain measurement was demonstrated with a FBG in a conventional single-mode fiber mounted on the surface of a vibrating cantilever and on a piezoelectric actuator, giving a resolution of 0.5 microepsilon at 2.4 kHz. We present results of this technique extended to measure the dynamic differential strain between two FBG pairs within a multicore fiber. An arbitrary cantilever oscillation of the multicore fiber was determined from curvature measurements in two orthogonal axes at 1125 Hz with a resolution of 0.05 m(-1).     

Distributed Fiber-Optic Sensor for Dynamic Strain Measurement

A novel Brillouin-based distributed sensing technique is presented that can obtain the strain profile of the entire sensing fiber with a single optical pulse. Experimentally obtained spectra show that this comb excited pump signal is capable of strain and temperature measurement in a dynamic system. The results show the expected sinusoidal strain profile for a 12 s periodic strain cycle applied to the test fiber. The strain distribution for the entire fiber was obtained in 256 mus , thereby demonstrating for the first time, the potential to measure dynamic strains up to 3.9 kHz with 12 m resolution. Increased acquisition speed comes at the expense of achievable spatial resolution.     

分布式光纤传感技术应变测量试验研究

基于布里渊散射原理的布里渊光时域反射技术利用布里渊散射光的光谱技术和光时域测量技术,可对光纤沿线的温度、应变进行分布式监测。通过试验研究了分布式光纤传感技术在应变测量中的空间分辨率、应变分辨率、应变测量精度。研究结果表明,分布式光纤传感技术应变测量能够较准确地测得被测量结构上任何一点的应变,空间最小分辨率0.1m,应变测量分辨率和精度满足工程监测要求,可以在工程监测中作为一种新型分布式应变监测技术加以推广。     

Optical grating diffraction method: from strain microscope to strain gauge

The grating diffraction method for direct strain measurement is reviewed. Two systems which use this method are presented. The first system is a compact strain microscope. A Leitz optical transmitting microscope with white light source is reconstructed by developing a loading and recording system. Gratings with median density of between 40 and 200 lines/mm are used. With the help of a Bertrand lens, the Fourier spectrum of the grating is formed with high image quality on the CCD sensor plane. Software is developed to precisely, quickly and automatically determine the diffraction spot centroids. The second system is a new strain sensor based on a high-frequency grating and two Position Sensor Detectors (PSDs). The grating, attached to the surface of the specimen, is illuminated by a focused laser beam, generally with a frequency of 1,200 lines/mm. The centroids of diffracted beam spots from the grating are automatically determined using two PSD sensors connected to a personal computer. The shift of diffracted beam spots due to specimen deformation is detected. Strain sensitivity of one micro-strain can be obtained, as can a 0.4 mm spatial resolution for strain measurement. The system can be used for both static and dynamic tests.     

A technique for dynamic tensile testing of metals

A technique is described for obtaining full dynamic stress/strain curves in tension up to strain rates of 100^s-1. In conjunction with a high speed servo-hydraulic machine, a low inertia extensometer has been developed to facilitate measurement of specimen tensile strain up to fracture.
The benefits of the technique are highlighted in relation to currently available methods for dynamic stress/strain measurement.     

FBG传感器在微尺度计量中应用的前景

基于作者先前的实验数据和目前用FBG进行动态应力测量研究的实验，提出了把FBG传感器应用于微尺度计量领域的新概念，并展示了FBG在微尺度计量中应用的前景；简述了温度和应力同时测量的技术应用于分离和消除温度漂移的干扰；总结了动态应力产生布拉格波长偏移的解调装置并提出用其实现微尺度计量所需要的高分辨力的布拉格波长解调方法。     

Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars

The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case.