利用电容式传感器测量液位的研究

采用差动电容差压传感器测量液体的压力,利用液体的压力公式计算液位,设计了一种便携式低功耗液位仪。该仪器可以实现液位信号的采集和运算,同时还配有温度检测系统,通过软件编程对液位进行温度补偿,同时计算出液位值,最后结果由LCD显示。     

用于钢筋混凝土梁的光纤光栅应变传感器

在变形测定器中,光纤Bragg光栅被粘贴于内管的两端,这两端的距离确定了传感器的量规长度。为了测量拉应变和压应变,该光纤光栅必须保持处于与可能的最大压应变相等的永久性拉应变。将光纤Bragg光栅贴于H154梁的混凝土表面和H158梁的钢筋表面,以分别检测拉应变和压应变。当钢筋混凝土梁受到千斤顶的加载时,它的应变可由光纤Bragg光栅的反射Bragg波长的偏移量获得。实验表明,作为一种绝对检测器件,光纤Bragg光栅为钢筋混凝土梁提供了有效监测,其中,拉应变~1000me,而压应变~1500me。     

光纤液位传感器

光纤液位传感器ＡｎｂｏＷａｎｇ等１．前言液位测量在工业中获得了广泛的需求，尤其在石油和化学处理工业中。有时，有必要采用无电流传感触头这种安全方法来测量易燃液体的液位。液位测量可分为连续液位测量、离散液位测量和点液位测量。在近十五年期间，已经研制成功了...     

基于复合材料结构的光纤光栅传感器在动态称重系统中的应用探讨

介绍了光纤布喇格光栅传感器的肇本原理和优点,并对基于复合材料结构的光纤布喇格光栅称重传感器的应用进行了实验和探讨。     

基于双模LPFG折射率不敏感双参量传感器

环境折射率和环境温度变化是影响光纤应变测量误差的主要因素.本文利用双模光纤纤芯双模式(LP01和LP11)支持特性设计了一款环境折射率不敏感的双模光纤(DMF)长周期光纤光栅LPFG)应变传感器.设计了传感器模型结构,制作了最优化参数的传感器样品.实验测试了DMF-LPFG传感结构对外部环境中应变、温度和折射率的响应....     

光纤布喇格光栅反射波长移位的探测

综述了光纤布喇格光栅反射波长移位的探测方法。提出一种新的压电陶瓷－应变片组合探测光纤布喇格光栅反射波长的方法,它具有波长移位探测精度高、线性度好、结构紧凑等优点。     

分布式光纤光栅应变和温度同时测量系统

设计了分布式光纤光栅应变和温度同时测量系统,光源为时钟脉冲宽带光源,结合时分和波分复用技术解决光纤光栅传感网络的复用寻址问题,选用不同包层直径光纤相熔接的应变补偿法传感头设计方案,实现了温度和应变的同时测量.采用阵列波导光栅技术对传感信号进行解调,通过理论分析证实了系统方案的可行性.系统对应变和温度的测量范围为0～2500 με和25～120℃,误差分别为±17 με和±1℃.     

采用光纤布喇格光栅对的窄带光谱测试

利用光纤布喇格光栅的调谐特性,提出一个在光纤光栅调谐范围内对光纤光栅的布喇格波长、波长的漂移以及引起光纤光栅波长漂移的物理量进行检测的方案。采用悬臂梁结构,利用光纤布喇格光栅对的方法增大了光纤光栅的调谐范围。     

一种用于低频测量的光纤光栅振动传感器

利用光纤光栅敏感技术,设计了一种用于低频测量的光纤光栅振动传感器.该传感器采用了等强度悬臂梁作为振动传感元件,并在等强度悬臂梁的上下双面优化布置性能匹配的两个光纤光栅,一个为振动敏感测量光栅,另一个为信号匹配滤波解调光栅.该结构设计可以补偿温度的不利影响,同时也提高了传感器信号检测的灵敏度.实测结果表明,该传感器可以用于25 Hz以下的低频目标的振动测量.     

基于双折射效应的光纤光栅称重方法研究

与通常的光纤光栅传感器原理不同,本文基于光纤在外界径向载荷作用下产生的双折射效应为原理,建立了一套简单的称重实验装置,并对其检测原理进行了详细的分析。实验表明,这种光纤光栅称重传感器适合大载荷情况的重量检测问题,特别适合于公路计重收费系统中对车辆载重的监测领域,其称重灵敏度可达5kg。     

Temperature-insensitive fiber Bragg grating tilt sensor

A temperature-insensitive optical fiber tilt sensor is presented. The sensor scheme uses a prestrained fiber Bragg grating to sense the strain, which depends on the tilt angle. To compensate for the temperature effect, materials that have different linear thermal expansion behaviors are used for implementation of the sensor body. The differentiation in the linear thermal expansion would then cause a counter effect to the original temperature effect. Experimental tests show an accuracy of +/-0.167 degrees in tilt angle measurement. A temperature stability better than +/-0.33 degrees over the temperature range from 27 degrees C to 75 degrees C is demonstrated. The resolution 0.0067 degrees in tilt angle measurement is achieved by using our preliminary sensor with a dimension of 1 6 x 5 x 5 cm(3).     

Fast fiber-optic tunable filter based on axial compression on a fiber Bragg grating

We describe the design, fabrication, and performance of a fiber Bragg grating-based tunable optic filter. The filter, driven by two piezostacks, consists of a flexural hinge structure for displacement magnification and a fiber-ferrule assembly for axial compression of the fiber grating. Finite-element analysis was used to design the mechanical structure to achieve the required displacement magnification and the force for grating compression. A passive thermal compensation design was implemented to reduce thermal-induced wavelength drift. A feedback control system with a linear variable differential transformer was employed to control the displacement for accurate wavelength tuning and fine-tuning resolution. This tunable filter has achieved a closed-loop switching time of 17.3 ms, and a passive thermal compensation that reduced the thermal drift of the Bragg wavelength to 1.5 pm/C. The flexural-hinge structure that offers negligible backlash, noise-free motion, no need of lubricants, and no wear ensures its long-term reliability.     

Design and characteristics of refractive index sensor based on thinned and microstructure fiber Bragg grating

A refractive index sensor based on the thinned and microstructure fiber Bragg grating (ThMs-FBG) was proposed and realized as a chemical sensing. The numerical simulation for the reflectance spectrum of the ThMs-FBG was calculated and the phase shift down-peak could be observed from the reflectance spectrum. Many factors influencing the reflectance spectrum were considered in detail for simulation, including the etched depth, length, and position. The sandwich-solution etching method was utilized to realize the microstructure of the ThMs-FBG, and the photographs of the microstructure were obtained. Experimental results demonstrated that the reflectance spectrum, phase shift down-peak wavelength, and reflected optical intensity of the ThMs-FBG all depended on the surrounding refractive index. However, only the down-peak wavelength of the ThMs-FBG changed with the surrounding temperature. Under the condition that the length and cladding diameter of the ThMs-FBG microstructure were 800 and 14 mum, respectively, and the position of the microstructure of the ThMs-FBG is in the middle of grating region, the refractive index sensitivity of the ThMs-FBG was 0.79 nm/refractive index unit with the wide range of 1.33-1.457 and a high resolution of 1.2 x 10(-3). The temperature sensitivity was 0.0103 nm/ degrees C, which was approximately equal to that of common FBG.     

Temperature sensor based on the power reflected by a Bragg grating in a tapered fiber

We present a temperature sensor based on two chirped gratings made in optical fibers tapered by fusion. One of the gratings has a metallic shielding and acts as sensor element, whereas the second grating provides a reference signal. The sensor is interrogated by measuring the power reflected by the two gratings, and the system has an accuracy of 0.05 degrees C over a linear operation range of more than 10 degrees C that can be adjusted in the fabrication process.     

Multiple fiber Bragg grating sensor system using code-division multiple access

We propose and demonstrate experimentally a multiple fiber Bragg grating sensor system that uses a LED as a light source and adapts the code-division multiple access method to separate individual sensor signals. We measured static and dynamic strains and cross-talk levels among sensor signals. With our proposed scheme, a low-cost sensor system can be designed with a fast response speed. Cross-talk levels between sensor signals are found to be below the -30-dB level.     

Pointwise fiber Bragg grating displacement sensor system for dynamic measurements

A method for setting up a fiber Bragg grating (FBG) sensor which can measure the pointwise, out-of-plane or in-plane dynamic displacement is proposed. The proposed FBG sensor is reusable. A multiplexing demodulation system based on a single long-period fiber grating is used in this study. The experimental results of the steady-state motion for a multilayer piezoelectric actuator and the dynamic response of a cantilever beam subjected to impact loadings are presented. These results indicate that the proposed displacement sensor has the ability to measure the out-of-plane dynamic displacement with high sensitivity. Measurements for a piezoceramic plate excited by high frequency show that the proposed displacement sensor also has the ability to provide the in-plane dynamic displacement up to 20 kHz.     

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。     

光纤Bragg光栅应变传感器在霍普金森压杆上的冲击试验研究

利用复合材料封装光纤Bragg光栅(FBG)设计制作了用于测量高速碰撞或爆炸与冲击作用下混凝土内部动态应变的FBG应变传感器。在霍普金森压杆上对FBG在封装前的裸光栅和封装后的FBG传感器分别进行了高速冲击试验,试验表明：设计的FBG传感器的瞬态响应上升时间小于20μs,具有良好的动态响应特性,可以用于工程中混凝土结构内高速冲击下的动态应变测试     

Extrinsic Fabry-Perot cavity optical fiber liquid-level sensor

An optical fiber liquid-level sensor based on an extrinsic Fabry-Perot (FP) cavity is proposed and demonstrated. The FP cavity consists of the end of the single-mode optical fiber and the elastic silicon layer. Liquid pressures act on the mechanical construction to change the cavity length, resulting in differential phase shifts that may be observed as variations of the output signal intensity. Self-compensated steps have been taken to obtain high accuracy and long-term stability in realistic circumstances. Experimental results indicate that accuracy of 2 mm over a full scale of 3.5 m (water) is obtained under ambient temperature 10-38 degrees C. The sensor can be used to measure liquid levels continuously and accurately in explosive and flammable environments.