共查询到20条相似文献,搜索用时 15 毫秒
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光纤布里渊温度和应变分布同时传感方法研究 总被引:2,自引:1,他引:1
布里渊分布型光纤温度和应变同时传感的方法主要有3种:布里渊散射谱双参量同时测量的方法、双布里渊频移同时测量的方法及联合拉曼散射和布里渊散射效应法.文章对这3种方法进行了深入的研究,阐述了实现各种方法的具体方案,并对其性能及成本进行了比较,给出了一种可实现温度和应变高精度同时测量的传感方案. 相似文献
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Xiaoyi Bao DeMerchant M. Brown A. Bremner T. 《Lightwave Technology, Journal of》2001,19(11):1698-1704
The structural strain measurement of tension and compression in the steel beam was demonstrated with a distributed fiber-optic sensor system based on Brillouin scattering. The experiments were conducted both in the laboratory and outdoors. When it is in the outdoor environment, the temperature compensation has been taken into account for the strain measurement due to sunlight radiation. The compressive strain has been measured, without needing pretension on the fiber with a Brillouin scattering-based distributed sensor system, when the fiber is glued to the steel beam at every point. The dynamic range in the strain measurement has been increased, due to the elimination of the pretension requirement. The spatial resolution of the strain measurement is 0.5 m. The strain measurement accuracy is ±10 με(μm/m) in the laboratory environment with nonuniform-distributed strain. With uniform strain distribution, the strain accuracy for this system can be. ~±5 με. These results were achieved with the introductions of a computer-controlled polarization controller, a fast digitizer-signal averager, a pulse duration control, and the electrical optical modulator bias setting in the software 相似文献
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We study the Brillouin scattering behavior in several single-mode fibers with different waveguide characteristics in terms of their longitudinal mode structures in the gain spectrum, linewidth narrowing, and stimulated Brillouin scattering (SBS) threshold levels. Evolution from spontaneous to SBS is investigated by monitoring the Brillouin line-shape and the behavior of the longitudinal acoustooptic resonance modes that exist in the core. We compare our results with the current theory of Brillouin scattering generated from noise in the undepleted pump approximation. We also present experimentally Brillouin gain spectra in the highly depleted pump regime, where there is no analytical solution, by showing the evolution of the gain spectrum as a function of the injected laser intensity. 相似文献
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The equations describing the stimulated Brillouin scattering process in optical fibers with distributed gain, including an equation for the second-order Stokes wave, are numerically solved. An analytical solution for the case of no net gain or loss is also presented. We note that the presence of distributed gain along the fiber leads to a nonmonotonous evolution of the signal power and to ready generation of multiple Stokes orders. The effect of broadening the signal spectrum, as well as the influence of a copropagating or counterpropagating signal are also examined 相似文献
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Lecoeuche V. Hathaway M.W. Webb D.J. Pannell C.N. Jackson D.A. 《Photonics Technology Letters, IEEE》2000,12(10):1367-1369
We report on a novel experimental setup for distributed measurement of temperature, based on spontaneous Brillouin scattering in optical fiber. We have developed a mode-locked Brillouin fiber ring laser in order to generate the dual frequency source required for a heterodyne detection of the backscattered signal. This relatively simple system enables temperature measurements over 20 km with a spatial resolution of 7 m. 相似文献
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A technique to measure distributed strain in optical fibers 总被引:2,自引:0,他引:2
The technique is based on Brillouin optical-fiber time-domain analysis (BOTDA), which uses Brillouin interaction between counterpropagating pump and probe light waves. Experimental results for fibers wound on drums at various tensions are presented. A strain measurement accuracy of better than 2×10-5 and a spatial resolution of 100 m are achieved 相似文献
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Long-length fiber-optic remote Raman sensors are used for distributed temperature measurements. Toward this aim, we apply optical-fiber frequency-domain reflectometry. The Raman intensity generated in single- and multimode optical fibers is theoretically investigated for sinusoidally intensity-modulated probe light. Thus, a proper sensor element and wavelength for fiber-optic Raman sensing is determined. Further, the temperature error for long sensor fibers is theoretically analyzed 相似文献
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Tateda M. Horiguchi T. Kurashima T. Ishihara K. 《Lightwave Technology, Journal of》1990,8(9):1269-1272
Strain distributions along optical fibers in a 1.3-km-long cable before and after installation are measured using Brillouin optical-fiber time domain analysis. The residual strains in the installed optical fibers were found to vary from zero to 0.07%, depending on the conduit configuration and installation procedure. Strain distribution measurements were carried out on a 24-fiber slotted-core type single-mode optical fiber cable for 1.55-μm-wavelength transmission, whose length, outer diameter, and weight were 1.3 km, 14 mm, and 0.18 kg/m, respectively. No clear relation between strain distributions and the fiber configuration in the test cable are found 相似文献
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Luc THVENAZ 《中国光电子学前沿》2010,3(1)
Optical fiber sensors based on stimulated Brillouin scattering have now clearly demonstrated their excellent capability for long-range distributed strain and temperature measurements. The fiber is used as sensing element, and a value for temperature and/or strain can be obtained from any point along the fiber. After explaining the principle and presenting the standard implementation, the latest developments in this class of sensors will be introduced, such as the possibility to measure with a spatial resolution of 10 cm and below while preserving the full accuracy on the determination of temperature and strain. 相似文献
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为了解决已敷设传感光纤中布里渊谱峰功率初值难以获取,基于频移和功率双参量的温度和应变区分测量误差大等问题,提出了解决方法。通过标定实验确定布里渊频移和相对谱峰功率的温度和应变系数、频移初始值;根据布里渊散射功率特性方程,通过试探法,利用已敷设光路中温度和应变已知的参考光纤确定方程系数,建立了谱峰功率初始值;利用归一化方法克服了传感系统中乘性噪声导致的测量误差;利用谱宽变化消除了温度和应变突变点处的谱峰功率异常峰值;最后,根据光纤复合海底电缆的现场情况建立了模拟光路,并进行了温度和应变测量实验。结果表明,在5.6 km处可实现4.3℃和110 的测量精度,可实现已敷设传感光纤整条光路上的温度和应变区分测量,为工程应用提供了理论和实验依据。 相似文献
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Stimulated Brillouin scattering (SBS) is an impairment seen in narrowband transmission over optical telecommunications fiber at high laser power. Accurate modeling is necessary to predict the strength of this phenomenon. One method of SBS control is the optimal design of the fiber radial index of refraction profile. Previous work has been limited to modeling optical fibers with one or more radial step changes in index. Here, the author derives and solves a general set of differential equations that allow the numerical solution of SBS spectral gain for an arbitrary radial index profile. Simulated and measured spectra are compared for several fibers with GeO/sub 2/-doped cores. It is found that radial material displacement plays a significant role in the SBS interaction in fibers with a complex radial index profile. 相似文献
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Potential of stimulated Brillouin scattering as sensing mechanism for distributed temperature sensors 总被引:4,自引:0,他引:4
It is demonstrated that stimulated Brillouin scattering (SBS) occurring in the core of an optical fibre may be used in the construction of a distributed temperature sensor. Initial experiments with a length of fibre have shown that the sensitivity of the Stokes frequency to temperature is approximately 5.5 MHz/ degrees C and that different Stokes frequencies may be observed according to the temperature distribution along the fibre.<> 相似文献
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分布式布里渊光纤应变传感信号的增敏检测方法 总被引:2,自引:2,他引:0
基于外差相干检测原理,摒弃了传统扫频构建布里渊散射频谱的方法,以布里渊散射光功率为应变监测参量,利用具有增敏作用的高频脉冲检波管对布里渊散射拍频信号进行包络检波,直接将拍频信号转换成布里渊散射功率信号,并对携带应变信息的布里渊散射功率信号进行应变增敏检测,利用高频脉冲检波管增益响应曲线对功率信号的调制提高散射功率应变敏感系数。经测试,增敏后布里渊散射光功率应变敏感系数为0.024%/με,与传统直接检测法得到的应变敏感系数-7.7×10-4%/με相比,敏感系数提高30倍,有效提高了系统信噪比;对增敏后的布里渊功率信号进行解调,在24.7km的光纤长度上,实现65με的应变测量标准差,测量时间由传统扫频方法的超过30s降为仅1s。本文系统可有效满足快速精确检测应变的监测需求,且不需要扫频模块等复杂器件,结构简单,稳定性高,对实际应用具有重要的意义。 相似文献
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The principles of operation, the design, and performance of a fiber-optic temperature-distribution sensor are discussed. The sensor uses optical time-domain reflectometry (OTDR) to detect temperature-induced changes of backscatter power at many separate locations in the fiber. In liquid-core fibers, a sensitivity of2.3 times 10^{-2} dB/°C (0.54 percent° C-1) was observed. A measurement accuracy of 1°C with a spatial resoltuion of 1 m is attainable over a fiber length of 100 m. 相似文献
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Interferometric sensors using optical fibers as a transduction medium have been shown to be sensitive to a variety of physical measurands. A result of this is that the resolution of a system designed to sense strain, for example, may be compromised by fluctuations in the temperature of the environment. The possibility of simultaneously determining the strain and temperature applied to the same piece of highly birefringent fiber is discussed. Second-order effects are shown to be important for long sensing lengths or in the presence of high strains or temperature changes. The results of experiments carried out to verify the theoretical predictions are also described 相似文献