摘要
布里渊光时域分析传感技术具有长传感距离、高测量精度以及可实现多参量监测等优势,被广泛应用于大型基础设施结构健康监测、管网泄露监测、电力电缆监控等重要领域。空间分辨率是区分小尺度温度或应变事件的关键指标,然而,传统技术受脉冲宽度限制难以突破米量级。为此,文中提出了一种基于渐进差分法的高空间分辨率传感解调方法,将光纤中单发长脉冲激发的布里渊散射信号时域曲线逐级进行前向差分,提取不同差分步长下差分增益曲线的最大值构成峰值差分增益曲线,进而实现小尺度事件解调。进一步,通过探测光频率扫描完成事件区布里渊频移提取及温度变化解调。与其他高空间分辨率技术相比,该方案的空间分辨率理论上由系统采样精度决定而与泵浦脉冲宽度无关。文中首先通过搭建仿真系统对该方案的原理和可行性进行了验证。然后,实验中采用40 ns单发长泵浦脉冲,在2 km传感光纤中实现了10 cm空间分辨率的分布式温度测量,将空间分辨率由米量级提升至亚米量级,且过程中无噪声预处理。
Objective Brillouin optical time-domain analysis sensing technology,with advantages such as long sensing distance,high measurement accuracy,and the ability of multi-parameter monitoring,is widely applied in important fields including structural health monitoring of large-scale infrastructure,pipeline leakage monitoring,and power cable monitoring.Spatial resolution is a key indicator for distinguishing small-scale temperature or strain events.However,traditional technologies are limited by pulse width and thus difficult to break through the meter-level resolution.For this purpose,a high-spatial-resolution scheme based on the progressive difference demodulation is proposed in this paper.Methods This paper proposes a high-spatial-resolution sensing demodulation scheme based on the progressive difference demodulation.Perform iterative forward differencing on the time-domain curve of the Brillouin scattering signal excited by a single-shot long pulse in the optical fiber,then the maximum values of the differential gain curves under different differential lengths are extracted to form a peak differential gain curve,and the spatial length corresponding to the rising edge is equal to the length of the event region.Based on this,high spatial resolution demodulation of small-sized events can be achieved(Fig.1).In addition,the Brillouin frequency shift extraction and temperature change demodulation in the event zone are achieved through frequency scanning of the probe light.Results and Discussions In the simulation system that constructed in this paper(Tab.1),the distributed temperature measurement with a spatial resolution of 20 cm is realized using a 40 ns single-shot long pulse(Fig.3).In the experiment,a 2 km sensing fiber with a 10 cm heated zone at the end of fiber is used,and a 40 ns pump pulse is used for excitation corresponding to a spatial resolution of 4 m.The time-domain curves of Brillouin scattering signals at each probe frequency scanning point are processed using the progressive difference demodulation proposed in this paper.The Brllouin frequency shift(BFS)values are measured as 10650 MHz in the non-heated zone and 10690 MHz in the heated zone,yielding a demodulated BFS difference of 40 MHz that corresponds to the temperature difference of 40℃(Fig.9).And localized the starting and ending points of the heated zone at 1975.06 m and 1975.162 m along the fiber respectively,and the corresponding length of the temperature zone is 10.2 cm,which is consistent with the experimental setting(Fig.10).Both experimental and simulation results conclusively validate the capability of the proposed method to resolve sub-meter events.Compared with other high spatial resolution technologies,the spatial resolution of this scheme is theoretically determined by the system sampling accuracy and is independent of the pump pulse width.Conclusions To overcome the limitation of pulse width on spatial resolution of Brillouin optical time-domain analysis system,this paper proposes a high-spatial-resolution scheme based on the progressive demodulation.By performing progressive difference demodulation on the time-domain curve of Brillouin scattering signals excited by a single-shot long pulse in fiber,the spatial resolution of the system is improved from the meter level to the centimeter level,without any noise preprocessing required during the process.
作者
张倩
朱亚琦
王大为
芦宾
张明江
ZHANG Qian;ZHU Yaqi;WANG Dawei;LU Bin;ZHANG Mingjiang(College of Computer Science and Artificial Intelligence,Shanxi Normal University,Taiyuan 030031,China;College of Physics and Optoelectronics,Taiyuan University of Technology,Taiyuan 030024,China)
出处
《红外与激光工程》
北大核心
2025年第10期231-239,共9页
Infrared and Laser Engineering
基金
国家自然科学基金项目(62441504,62475183)
山西省基础研究计划青年科学研究项目(202403021222248)。
关键词
分布式光纤传感
受激布里渊散射
布里渊光时域分析
空间分辨率
渐进差分解调
distributed optical fiber sensing
stimulated Brillouin scattering
Brillouin optical timedomain analysis
spatial resolution
progressive difference demodulation
作者简介
张倩,女,讲师,博士,主要从事分布式光纤传感监测方面的研究。
