Fiber Segment Interferometry for Bend-Resistant Temperature Sensing
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Solution Overview
Problem
Existing optical fiber sensors for temperature measurement, such as Fiber Bragg Grating and Fiber Segment Interferometry, face challenges in localized temperature measurement due to fiber bending-induced strain and weak measurement signals, especially in environments requiring multiple bends, leading to measurement errors and reduced accuracy.
Innovation Solution
An optical sensing method using a first optical fiber segment with a reference reflector and a sensing element having a higher thermo-optic coefficient than the fiber, where light is modulated over a broader bandwidth, allowing for precise temperature measurement by analyzing interference patterns from reflective surfaces, and a sensing element with tailored reflective coatings to enhance signal strength and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fiber Bragg Grating sensors are used for temperature measurement, then temperature can be measured, but fiber bending induces strain that results in measurement errors
Solution Approach 1:
The optical fiber is divided into multiple segments with different properties: a first optical fiber segment with low thermo-optic coefficient for strain compensation and a second optical fiber segment with high thermo-optic coefficient for temperature sensing. This segmentation allows the system to separate temperature measurement function from strain sensitivity, resolving the contradiction between measurement accuracy and bending-induced errors.
Solution Approach 2:
Different regions of the optical fiber system are assigned different functional qualities: the first fiber segment is optimized for strain insensitivity (low thermo-optic coefficient) while the second segment is optimized for temperature sensitivity (high thermo-optic coefficient). This local differentiation enables the system to maintain measurement precision while accommodating necessary fiber bends for routing around battery cells.
2Adaptability or versatility
If multiple fiber bends are used to route sensors around battery cells, then installation flexibility is improved, but measurement accuracy deteriorates due to strain
Solution Approach 1:
The fiber system is segmented into a first segment designed to accommodate bends without introducing measurement errors (low thermo-optic coefficient) and a second segment that performs the actual temperature measurement (high thermo-optic coefficient). This allows installation flexibility through bending while maintaining measurement accuracy in the sensing segment.
Solution Approach 2:
The first optical fiber segment acts as an intermediary that transmits light to and from the second sensing segment while being insensitive to bending-induced strain. This intermediary segment absorbs the mechanical stress of routing around battery cells, protecting the measurement function from degradation.
3Measurement precision
If sensing elements with higher thermo-optic coefficient are used, then temperature sensitivity is improved, but the system complexity increases
Solution Approach 1:
The system exploits changes in the thermo-optic coefficient parameter by selecting materials with dramatically different coefficients (silica fiber: 10^-5/K vs. silicon: 10^-4/K). This parameter differentiation enables high temperature sensitivity in the sensing element while using standard optical fiber infrastructure, avoiding excessive system complexity.
Solution Approach 2:
The sensing element combines silicon (high thermo-optic coefficient) with optical fiber (low thermo-optic coefficient) to create a composite structure that achieves high temperature sensitivity while maintaining compatibility with existing optical sensing infrastructure. This composite approach balances performance enhancement with system simplicity.
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
The method enables accurate temperature measurement without fiber curvature, enhancing sensitivity and reducing measurement errors by leveraging a sensing element with a higher thermo-optic coefficient and tailored reflective surfaces, improving measurement accuracy and signal strength.
Implementation Method 1
the sensing element has a thermo-optic coefficient that is larger in magnitude than the thermo-optic coefficient of the first optical fiber
Implementation Method 2
A first reflected portion of the light emitted from the light source is reflected from the reference reflector. A second reflected portion of the light emitted from the light source is reflected from the sensing element.
Implementation Method 3
A temperature of the sensing element is based on the influence of the thermo-optic coefficient of the sensing element on the light detected by the photodetector
Data Source
AI summary
An optical sensor system is adapted for a sensing method using fiber segment interferometry. A sensing element with a thermo-optic coefficient larger than the thermo-optic coefficient of an optical fiber is arranged at a distal end of the fiber.