Multi-Core Fiber Sensor for Strain-Temperature Separation
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Solution Overview
Problem
Conventional Brillouin fiber sensors face challenges in distinguishing between strain and temperature changes, as the Brillouin frequency shift is a function of both parameters, making it difficult to measure strain and temperature effectively over long distances in applications like structural health monitoring and geotechnical engineering.
Innovation Solution
A Brillouin-based distributed bend fiber sensor system utilizing a four-core optical fiber with separate cores for measuring bend-induced strains and temperature, employing Brillouin Optical Time Domain Reflectometry (BOTDR) or Brillouin Optical Time Domain Analysis (BOTDA) techniques to differentiate between strain and temperature effects by calculating changes in Brillouin frequency shifts across each core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Brillouin fiber sensors are used to measure strain and temperature, then the Brillouin frequency shift can be obtained, but it is difficult to distinguish between strain and temperature changes because the frequency shift is a function of both parameters
Solution Approach 1:
The patent divides the fiber into multiple cores (first core, second core, third core, fourth core) where different cores are used to measure different parameters. The first and second cores measure bend-induced strain, while the third and fourth cores measure temperature, allowing independent measurement of strain and temperature without interference between the two measurements.
Solution Approach 2:
Each core of the fiber is assigned a specific measurement function with different sensitivity characteristics. The first and second cores are optimized for strain measurement while the third and fourth cores are optimized for temperature measurement, creating local functional differentiation that enables simultaneous independent measurement of both parameters.
2Length of stationary object
If conventional Brillouin fiber sensors are used for long-distance monitoring, then the measurement range is extended, but the ability to distinguish between strain and temperature effects deteriorates
Solution Approach 1:
The fiber is segmented into multiple cores that are spatially separated and functionally differentiated. This segmentation allows each core to be optimized for its specific measurement function while maintaining the ability to distinguish between strain and temperature effects over long distances through the distributed sensing architecture.
Solution Approach 2:
The multi-core fiber structure provides multi-functionality where the same fiber bundle can simultaneously perform strain measurement, temperature measurement, and spatial distribution mapping over long distances. The system achieves universality by enabling multiple measurement functions within a single distributed sensing platform.
3Reliability
If traditional monitoring methods are used, then measurement capabilities are provided, but the cost is higher compared to the Brillouin-based distributed sensor system
Solution Approach 1:
The patent merges multiple measurement functions (strain sensing, temperature sensing, spatial distribution) into a single integrated fiber optic sensor system. By combining these functions in one distributed sensing platform rather than using separate systems, the overall cost is reduced while maintaining comprehensive monitoring capabilities.
Solution Approach 2:
The multi-core fiber sensor system provides universal measurement capabilities for both strain and temperature over long distances, replacing the need for multiple separate sensing systems. This multi-functionality reduces system complexity and cost while maintaining or improving reliability compared to traditional separate monitoring methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables simultaneous measurement of bend angle, bend radius, and temperature distribution along deployed fibers, effectively distinguishing between strain and temperature changes, thereby improving monitoring capabilities in long-distance applications with lower costs compared to traditional methods.
Implementation Method 1
obtain, prior to deployment of the fiber when the fiber has no bend applied thereto, from the Brillouin backscattering mechanism a first Brillouin frequency shift (BFS) baseline measurement (vB1) along the first core, a second BFS baseline measurement (vB2) along the second core, a third BFS baseline measurement (vB3) along the third core, and a fourth BFS baseline measurement (vB4) along the fourth core
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
A Brillouin-based distributed bend fiber sensor and method for using the Brillouin-based distributed bend fiber sensor are described herein. In one example, the Brillouin-based distributed bend fiber sensor is specially configured to measure a temperature distribution ( ΔT), a bend angle β, and a bend radius R along a deployed fiber (e.g., four-core fiber).