Brillouin scattering spectrum-based crack measurement using distributed fiber optic sensing

2021 ◽  
pp. 147592172110309
Author(s):  
Ruonan Ou ◽  
Linqing Luo ◽  
Kenichi Soga
Keyword(s):  
Spatial Resolution ◽  
Large Scale ◽  
Fiber Optic ◽  
Brillouin Scattering ◽  
Maximum Strain ◽  
Large Scale Structures ◽  
Scattering Spectrum ◽  
Transverse Joint ◽  
Fiber Optic Sensing ◽  
Bonded Concrete Overlay

Brillouin scattering-based distributed fiber optic sensing (Brillouin-DFOS) technology is widely used in health monitoring of large-scale structures with the aim to provide early warning of structural degradation and timely maintenance and renewal. Material cracking is one of the key mechanisms that contribute to structural failure. However, the conventional strain measurement using the Brillouin-DFOS system has a decimeter-order spatial resolution, and therefore it is difficult to measure the highly localized strain generated by a sub-millimeter crack. In this study, a new crack analysis method based on Brillouin scattering spectrum (BSS) data is proposed to overcome this spatial resolution-induced measurement limitation. By taking the derivative of the BSS data and tracking their local minimums, the method can extract the maximum strain within the spatial resolution around the measurement points. By comparing the variation of the maximum strain within the spatial resolution around different measurement points along the fiber, cracks can be located. The performance of the method is demonstrated and verified by locating and quantifying a small gap created between two wood boards when one of the wood boards is pushed away from the other. The test result verifies the accuracy of the crack strain quantification of the method and proves its capability to measure a sub-millimeter crack. The method is also applied to a thin bonded concrete overlay of asphalt pavement field experiment, in which the growth of a transverse joint penetrating through the concrete–asphalt interface was monitored. The method successfully locates the position, traces the strain variation, and estimates the width of a crack less than [Formula: see text] wide using a Brillouin-DFOS system with [Formula: see text] spatial resolution.

Improved distributed fiber optic sensing system based on single-ended double-pulse input Brillouin scattering

2014 ◽  
Author(s):  
Tianying Chang ◽  
Ruijuan Yang ◽  
Yongliang Wang ◽  
David Y. Li ◽  
Lei Jia ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Brillouin Scattering ◽  
Double Pulse ◽  
Pulse Input ◽  
Sensing System ◽  
Fiber Optic Sensing

scholarly journals Application of distributed fiber optic sensing technique in land subsidence monitoring in coastal areas: a case study in Tianjin, China

2020 ◽  
Vol 382 ◽  
pp. 137-141
Author(s):  
Su-Ping Liu ◽  
Bin Shi ◽  
Kai Gu ◽  
Cheng-Cheng Zhang ◽  
Song Zhang ◽  
...  
Keyword(s):  
Land Subsidence ◽  
Fiber Optic ◽  
Brillouin Scattering ◽  
Coastal Areas ◽  
The Novel ◽  
Fiber Optic Sensing ◽  
Monitoring Technologies ◽  
Subsidence Monitoring ◽  
Good Agreement

Abstract. Land subsidence is a worldwide geohazard caused by various factors, and its direct impact is loss of elevation, which is especially severe in coastal areas due to sea level rise. Quantifying contributions of compressed strata is significant for evaluating the subsidence. In this paper, we used distributed fiber optic sensing (DFOS) with Brillouin scattering to monitor the strain distribution along optical cables embedded in a borehole located in Tianjin, China. The novel technique revealed that the land subsidence rate was 21.2 mm a−1 from 2017 to 2019. The strata contributed to the subsidence have been identified in the range of 3 to 35 m. The results showed good agreement with those obtained by a group of extensometers. We demonstrated that DFOS could be a supplement to land subsidence monitoring technologies in coastal areas.

scholarly journals Land subsidence monitoring using distributed fiber optic sensing with Brillouin scattering in coastal and deltaic regions

2020 ◽  
Vol 382 ◽  
pp. 95-98
Author(s):  
Kai Gu ◽  
Su-Ping Liu ◽  
Bin Shi ◽  
Yi Lu ◽  
Yue-Hua Jiang
Keyword(s):  
Land Subsidence ◽  
Land Surface ◽  
Fiber Optic ◽  
Brillouin Scattering ◽  
Surface Displacement ◽  
Yangtze River Delta ◽  
Deformation Distribution ◽  
Conventional Methods ◽  
Fiber Optic Sensing ◽  
Subsidence Monitoring

Abstract. Excessive withdrawal of groundwater in coastal and deltaic regions is one of the main reasons which induce land subsidence in these areas. Land surface displacement monitoring with conventional methods is not able to pinpoint subsurface compacting, which is very challenging. Instead of groups of extensometers, we apply distributed fiber optic sensing (DFOS) with Brillouin scattering in vertical boreholes to identify the deformation distribution along the entire borehole with meter-scale spatial resolution. We here present 10 boreholes with depths range from 100 to 600 m with DFOS monitoring along the east coastal line of Jiangsu and Shanghai since 2015, and 1 borehole of 300 m in depth in Yangtze River delta since 2012. The results provide clear images on the deformation distribution along entire boreholes, by identifying the main contributors to the subsidence and the deformation evolutionary processes, with stable long-term monitoring performance. Hence, we demonstrate that DFOS can open window into subsurface deformation and could be important complementary to conventional methods to understand the land subsidence processes in coastal and deltaic regions.

scholarly journals Brillouin Optical Correlation-Domain Technologies Based on Synthesis of Optical Coherence Function as Fiber Optic Nerve Systems for Structural Health Monitoring

2019 ◽  
Vol 9 (1) ◽  
pp. 187 ◽  
Author(s):  
Kazuo Hotate
Keyword(s):  
Optic Nerve ◽  
Spatial Resolution ◽  
Health Monitoring ◽  
Fiber Optic ◽  
Brillouin Scattering ◽  
Coherence Function ◽  
Optical Coherence ◽  
Optical Correlation ◽  
Stimulated Brillouin ◽  
Optical Coherence Function

Brillouin optical correlation-domain technologies are reviewed as “fiber optic nerve systems” for the health monitoring of large structures such as buildings, bridges, and aircraft bodies. The Brillouin scattering property is used as a sensing mechanism for strain and/or temperature. Continuous lightwaves are used in the technologies, and their optical coherence properties are synthesized to realize position-selective measurement. This coherence manipulation technology is called the “synthesis of optical coherence function (SOCF)”. By utilizing SOCF technologies, stimulated Brillouin scattering is generated position-selectively along the fiber, which is named “Brillouin optical correlation domain analysis (BOCDA)”. Spontaneous Brillouin scattering, which takes place at any portion along the fiber, can also be measured position-selectively by the SOCF technology. This is called “Brillouin optical correlation domain reflectometry (BOCDR)”. When we use pulsed lightwaves that have the position information, sensing performances, such as the spatial resolution, are inherently restricted due to the Brillouin scattering nature. However, in the correlation-domain technologies, such difficulties can be reduced. Superior performances have been demonstrated as distribution-sensing mechanisms, such as a 1.6-mm high spatial resolution, a fast measurement speed of 5000 points/s, and a 7000-με strain dynamic range, individually. The total performance of the technologies is also discussed in this paper. A significant feature of the technologies is their random accessibility to discrete multiple points that are selected arbitrarily along the fiber, which is not realized by the time domain pulsed-lightwave technologies. Discriminative and distributed strain/temperature measurements have also been realized using both the BOCDA technology and Brillouin dynamic grating (BDG) phenomenon, which are associated with the stimulated Brillouin scattering process. In this paper, the principles, functions, and applications of the SOCF, BOCDA, BOCDR, and BDG-BOCDA systems are reviewed, and their historical aspects are also discussed.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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