Improvement of spatial resolution for strain measurements by analyzing Brillouin gain spectrum

2005 ◽  
Author(s):  
H. Murayama ◽  
K. Kageyama ◽  
A. Shimada ◽  
A. Nishiyama
Keyword(s):  
Spatial Resolution ◽  
Gain Spectrum ◽  
Strain Measurements ◽  
Brillouin Gain

Subdivision of Brillouin gain spectrum to improve the spatial resolution of a BOTDA system

2019 ◽  
Vol 58 (2) ◽  
pp. 466 ◽  
Author(s):  
Jiang Chao ◽  
Xiaoyan Wen ◽  
Weirun Zhu ◽  
Li Min ◽  
Haifei Lv ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Gain Spectrum ◽  
Brillouin Gain

scholarly journals Improvement of Performance for Raman Assisted BOTDR by Analyzing Brillouin Gain Spectrum

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 116
Author(s):  
Qiang Huang ◽  
Junqiang Sun ◽  
Wenting Jiao ◽  
Li Kai
Keyword(s):  
Spatial Resolution ◽  
Measurement Accuracy ◽  
Gain Spectrum ◽  
Analysis Method ◽  
Optical Time Domain Reflectometer ◽  
Starting Point ◽  
First Occurrence ◽  
Brillouin Gain ◽  
Optical Time ◽  
The Mathematical Model

We propose a simplified partitioned Brillouin gain spectrum (BGS) analysis method to enhance the spatial resolution and measurement accuracy of a Brillouin optical time-domain reflectometer (BOTDR) assisted by a first-order Raman pump. We theoretically derive the mathematical model of the partitioned BGS and analyze the superposition process of sub-Brillouin signals within a theoretical spatial resolution range. We unified all the unknown constant parameters of the calculation process to simplify the partitioned BGS analysis method and the value of the uniform parameter is attained through the system test data and numerical analysis. Moreover, to automate data processing, the starting point of the temperature/strain change is determined by the first occurrence of the maximum Brillouin frequency shift (BFS), then the position where the partitioned BGS analysis method calculation begins is obtained. Using a 100 ns probe pulse and partitioned BGS analysis method, we obtain a spatial resolution of 0.4 m in the 78.45-km-long Raman-assisted BOTDR system, and the measurement accuracy is significantly improved. In addition, we achieve a strain accuracy of 5.6 με and a spatial resolution of 0.4 m in the 28.5-km-long BOTDR without Raman amplification.

scholarly journals Measurement Improvement of Distributed Optical Fiber Sensor via Lorenz Local Single Peak Fitting Algorithm

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1166
Author(s):  
Bin Liu ◽  
Jianping He ◽  
Shihai Zhang ◽  
Yinping Zhang ◽  
Jianan Yu ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Frequency Shift ◽  
Optical Fiber Sensor ◽  
Gain Spectrum ◽  
Fiber Sensor ◽  
Peak Fitting ◽  
Fitting Algorithm ◽  
Distributed Optical Fiber Sensor ◽  
Brillouin Gain ◽  
Distributed Optical Fiber

Brillouin frequency shift (BFS) of distributed optical fiber sensor is extracted from the Brillouin gain spectrum (BGS), which is often characterized by Lorenz type. However, in the case of complex stress and optical fiber self damage, the BGS will deviate from Lorenz type and be asymmetric, which leads to the extraction error of BFS. In order to enhance the extraction accuracy of BFS, the Lorenz local single peak fitting algorithm was developed to fit the Brillouin gain spectrum curve, which can make the BSG symmetrical with respect to the Brillouin center frequency shift. One temperature test of a fiber-reinforced polymer (FRP) packaged sensor whose BSG curve is asymmetric was conducted to verify the idea. The results show that the local region curve of BSG processed by the developed algorithm has good symmetry, and the temperature measurement accuracy obtained by the developed algorithm is higher than that directly measured by demodulation equipment. Comparison with the reference temperature, the relative measurement error measured by the developed algorithm and BOTDA are within 4% and 8%, respectively.

scholarly journals Super Resolution Digital Image Correlation (SR-DIC): an Alternative to Image Stitching at High Magnifications

2021 ◽  
Author(s):  
R. S. Hansen ◽  
D. W. Waldram ◽  
T. Q. Thai ◽  
R. B. Berke
Keyword(s):  
High Resolution ◽  
Digital Image Correlation ◽  
Spatial Resolution ◽  
Digital Image ◽  
Super Resolution ◽  
Image Correlation ◽  
Low Resolution ◽  
Strain Measurements ◽  
Resolution Image ◽  
High Resolution Image

Abstract Background High-resolution Digital Image Correlation (DIC) measurements have previously been produced by stitching of neighboring images, which often requires short working distances. Separately, the image processing community has developed super resolution (SR) imaging techniques, which improve resolution by combining multiple overlapping images. Objective This work investigates the novel pairing of super resolution with digital image correlation, as an alternative method to produce high-resolution full-field strain measurements. Methods First, an image reconstruction test is performed, comparing the ability of three previously published SR algorithms to replicate a high-resolution image. Second, an applied translation is compared against DIC measurement using both low- and super-resolution images. Third, a ring sample is mechanically deformed and DIC strain measurements from low- and super-resolution images are compared. Results SR measurements show improvements compared to low-resolution images, although they do not perfectly replicate the high-resolution image. SR-DIC demonstrates reduced error and improved confidence in measuring rigid body translation when compared to low resolution alternatives, and it also shows improvement in spatial resolution for strain measurements of ring deformation. Conclusions Super resolution imaging can be effectively paired with Digital Image Correlation, offering improved spatial resolution, reduced error, and increased measurement confidence.

Simulating and Designing Brillouin Gain Spectrum in Single-Mode Fibers

2004 ◽  
Vol 22 (2) ◽  
pp. 631-639 ◽  
Author(s):  
Y. Koyamada ◽  
S. Sato ◽  
S. Nakamura ◽  
H. Sotobayashi ◽  
W. Chujo
Keyword(s):  
Single Mode ◽  
Gain Spectrum ◽  
Brillouin Gain
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