共查询到19条相似文献,搜索用时 109 毫秒
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建立了基于BOTDA(布里渊光时域分析技术)的分布式传感实验系统,该系统由150 mW窄带激光器、50 mw窄带激光器、声光调制器、脉冲发生器、环形器、频率计数器、光电探测器及相应光学器件组成.进行了温度传感试验,获得传感光纤处于25℃、35℃、45℃及55℃时的布里渊频移谱,通过对不同温度下频移谱峰值进行拟舍得出该系统的温度系数.进行了分布式光纤温度传感试验,将传感光纤分成3段,中间段置于温控箱中,调节温控箱的温度,使中间段温度不同于其他两段,扫描泵浦激光频率,使得处于室温下的传感光纤中发生受激布里渊散射,利用示波器获取了当光脉冲为2μs时系统输出电压信号波形. 相似文献
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34km传感长度的布里渊光时域反射计的设计与实现 总被引:3,自引:0,他引:3
布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电光调制产生频率可调的参考光,和散射光进行相干检测,根据散射光频移特性,应用电信号处理技术取出布里渊散射光电信号,并采用偏振控制技术来抑制相干检测的偏振相干性,再经过数字信号累加和平均处理,最后得到分布式传感信号。采用光相干检测设计方案实现了布里渊时域反射计分布式光纤传感器,并进行了34km光纤的分布式应变传感实验。 相似文献
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分布式光纤温度传感器的研究现状及趋势 总被引:1,自引:0,他引:1
阐述了分布式光纤温度传感技术的研究进展,主要介绍了基于后向瑞利散射、后向拉曼散射和后向布里渊散射的分布式光纤温度传感技术,并在此基础上分析了分布式光纤温度传感器的发展趋势. 相似文献
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分布式光纤应变传感器的研究 总被引:1,自引:0,他引:1
根据光纤中的布里渊散射频移与光纤所受的拉伸应变有关的特性,提出了基于光频域反射法的分布式光纤应变测量系统,采用光纤光栅法布里-珀罗干涉仪对布里渊频移进行直接测量的新方法,给出了实验系统及实验结果,证明了该方案的可行性. 相似文献
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基于BOTDR的分布式光纤传感器标定实验研究 总被引:4,自引:0,他引:4
针对基于布里渊散射原理的分布式传感光纤的标定问题,本文研发了一套分布式传感光纤标定系统。利用BOTDR测量仪器,可以标定分布式传感光纤的应变系数和温度系数,并获得Ф=900μm的尼龙紧套单模传感光纤的温度系数和应变系数:分别为2.99MHz/℃和0.05MHz/με;同时获得BOTDR实测值与真实应变的关系曲线,其相关系数大于0.995。该结果证明,普通通讯用紧套单模光纤可以用作分布式传感光纤,文中的标定方法及标定结果可为分布式传感光纤研究提供重要的研究手段及研究依据。 相似文献
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《仪表技术与传感器》2017,(12)
基于布里渊光时域反射计(BOTDR)设计了应变检测系统,用于采空区的沉降监测。该系统使用窄线宽激光器和高消光比光调制器产生脉冲光,并通过相干探测和微波扫频获取高信噪比的原始信号,最后采用洛仑兹曲线拟合算法解调出布里渊频移分布曲线。实验中,选用10.19 km的传感光纤,在末端3.9 m长度光纤上施加不同应变,以模拟采空区的沉降,解调的频移误差为2.1 MHz,对应应变测量误差为48.7με,该系统能为采空区的沉降监测提供一种方案和技术。 相似文献
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O'Keeffe P Bolognesi P Coreno M Moise A Richter R Cautero G Stebel L Sergo R Pravica L Ovcharenko Y Avaldi L 《The Review of scientific instruments》2011,82(3):033109
A velocity map imaging/ion time-of-flight spectrometer designed specifically for pump-probe experiments combining synchrotron and laser radiations is described. The in-house built delay line detector can be used in two modes: the high spatial resolution mode and the coincidence mode. In the high spatial resolution mode a kinetic energy resolution of 6% has been achieved. The coincidence mode can be used to improve signal-to-noise ratio for the pump-probe experiments either by using a gate to count electrons only when the laser is present or by recording coincidences with the ion formed in the ionization process. 相似文献
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《Measurement》2016
Distributed Brillouin sensing systems (DBSs) have growing applications in engineering and are attracting attention in the field of underground structures, including mining. The capability for continuous measurements of strain over large distances makes DBSs a promising monitoring approach for understanding deformation field evolution within a rock mass, particularly when the sensor is installed away from excavation damaged zone (EDZ). A purpose-built fiber optic sensing cable, a vital component of DBSs, was assessed in laboratory conditions.A test program was performed to observe DBSs response to various perturbations including strain and joint movements, including opening and shearing of joints. These tests included assessment of the strain-free cable response and the application of extensional and lateral displacement to various sensing cable lengths (strained lengths), from 1 m down to 1 cm. Furthermore, tests were done to evaluate the time-dependent behavior of the cable and to observe the effect of strain transfer using a soft host material (e.g. a soft grout) under lateral displacement.The noise level of the DBSs range was ±77 με, determined through repeated measurements on an unstrained cable. Stretching test results showed a clear linear correlation between applied strain and Brillouin frequency shift change for all strained lengths above half the spatial resolution of the DBSs. However, for strained lengths shorter than half the spatial resolution, no strain response was measurable and this is due to the applied internal signal processing of the DBSs to detect peak Brillouin gain spectrum and noise level. The stability with time of the measurements was excellent for test periods up to 15 h.Lateral displacement test results showed a less consistent response compared to tension tests for a given applied displacement. Although the Brillouin frequency shift change is correlated linearly with the applied displacement in tension, it shows a parabolic variation with lateral displacement. Moreover, the registered frequency response (correlated with strain) of the system decreased significantly when the sensing cable was embedded in a sand-filled tube compared with direct cable displacement. 相似文献
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《Measurement》2014
Brillouin optical fiber (OF) sensing technology shows superior potential for structural health monitoring with the advantages of distributed strain and temperature measurement, immunity of electromagnetic interference and so on. However most of current commercial Brillouin OF sensing systems have encountered spatial resolution bottleneck, which cannot deal with local high-precision measurement. A zigzag pattern of Brillouin OF sensor is developed explicitly for spatial resolution enhancement in this paper, and a relative zigzag optical fiber sensor is produced and packaged by fiber reinforced polymer (FRP). Their characteristics are studied by using the strain measurement of one small-size uniform strength beam. From the experiments, the zigzag pattern exhibits excellent performance for strain measurement with high-precision and enhances the spatial resolution to a certain degree without changing the Brillouin sensing instrument’s performance itself. 相似文献
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A maximum length sequence (MLS) is used to perform broadband impedance spectroscopy on a dielectric sample. The method has a number of advantages over other pulse-based or frequency sweep techniques. It requires the application of a very short sequence of voltage steps in the microsecond range and therefore allows the measurement of time-dependent impedance of a sample with high temporal resolution over a large bandwidth. The technique is demonstrated using a time-invariant passive RC network. The impedance of single biological cell flowing in a microfluidic channel is also measured, showing that MLS is an ideal method for high speed impedance analysis. 相似文献
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A simple modification to a Sandercock-type tandem Fabry-Pérot interferometer is demonstrated. By adding an independent reference laser with temperature tunability, narrow Brillouin lines that are tens GHz shifted from the Rayleigh line can be recorded with much higher frequency resolution than in the original system. 相似文献
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With the improvement of frequency standard comparison and precise frequency and phase processing technique, the high-precision frequency measurement, phase comparison, phase locked loop and signal processing are necessary. Combining phase synchronous detection principle and common frequency source, an ultra-high resolution phase comparison method is presented in this paper. Using the concepts of the equivalent phase comparison frequency, group period phase processing, phase group synchronization and phase quantization step and so on, and the high stability of common frequency source, the resolution with picosecond or subpicosecond can be easily obtained and ±1 count error in traditional phase comparison approach can be eliminated. Experimental results show that the measuring precision better than femtosecond in one hour can be achieved in the long-term frequency standard comparison. 相似文献
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《Mechanical Systems and Signal Processing》2003,17(3):533-549
It is shown in this paper that an extended Prony time–frequency plane representation can be developed in a similar way to the one represented in other traditional non-stationary analysis methods, such as the Wigner–Ville distribution. To do this, the original Prony procedure is carried out in a series of time shifts through an array of data. The ‘sliding window in time shifts approach’ of the developed technique is closer to the short Fourier transform without its time–frequency resolution drawback. Also, it is argued here that the extended Prony time–frequency plane representation is suitable for noise filtering through a component exponential damping selection. The extended technique capacity of performing non-stationary analysis is compared with the pseudo-Wigner–Ville distribution, and its capacity of filtering noise is demonstrated. 相似文献
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Spatially resolved recording of transient fluorescence‐lifetime effects by line‐scanning TCSPC 下载免费PDF全文
Wolfgang Becker Vladislav Shcheslavkiy Samuel Frere Inna Slutsky 《Microscopy research and technique》2014,77(3):216-224
We present a technique that records transient changes in the fluorescence lifetime of a sample with spatial resolution along a one‐dimensional scan. The technique is based on scanning the sample with a high‐frequency pulsed laser beam, detecting single photons of the fluorescence light, and building up a photon distribution over the distance along the scan, the arrival times of the photons after the excitation pulses and the time after a stimulation of the sample. The maximum resolution at which lifetime changes can be recorded is given by the line scan period. Transient lifetime effects can thus be resolved at a resolution of about one millisecond. We demonstrate the technique for recording photochemical and nonphotochemical chlorophyll transients in plants and transient changes in free Ca2+ in cultured neurons. Microsc. Res. Tech. 77:216–224, 2014. © 2014 Wiley Periodicals, Inc. 相似文献