FBG Optical Fibre Pressure Sensing With Redundant Interrogation
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Solution Overview
Problem
Existing systems for determining pressure changes in optical fibers, particularly in aircraft, are expensive and lack robustness, accuracy, and versatility.
Innovation Solution
A method and system utilizing Fiber Bragg Grating (FBG) patterns in optical fibers, with detectors and processors, employing combined wavelength division multiplexing and time division multiplexing to determine pressure changes, and utilizing redundant detector arrangements to provide automated, user-friendly, and cost-effective pressure change detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two detector arrangements are used in parallel for redundancy, then reliability is improved, but cost increases due to expensive optical fibre
Solution Approach 1:
The patent combines two detector arrangements into a single shared system where both detectors can interrogate the same optical fibre containing FBG sensors. This merging approach maintains redundancy and reliability while reducing the total amount of expensive optical fibre required, as the fibre is shared between both detector arrangements rather than requiring separate fibres for each detector.
Solution Approach 2:
The optical fibre is designed to serve multiple functions and be interrogated by multiple detector arrangements. The FBG patterns in the optical fibre can be read by either detector arrangement, making the system universal and flexible. This multi-functionality allows the same optical fibre to be used for redundancy purposes without requiring duplicate fibres for each detector.
2Measurement precision
If multiple Fibre Bragg Gratings are inscribed along the optical fibre, then measurement capability is improved, but difficulty of detecting and measuring increases due to wavelength overlap
Solution Approach 1:
Each Fibre Bragg Grating is assigned a unique wavelength range through local customization of the grating characteristics. This local quality approach ensures that each FBG reflects a distinct wavelength band, eliminating overlap issues. The patent implements this by inscribing FBGs with specific pitch and depth parameters that correspond to unique wavelength ranges, allowing precise identification of which FBG is being interrogated based on the reflected wavelength.
Solution Approach 2:
The optical spectrum is segmented into multiple distinct wavelength ranges, with each FBG assigned to a specific segment. This segmentation of the wavelength domain allows multiple FBGs to coexist on the same optical fibre without interference, as each operates in its own designated wavelength band. The detector arrangements can then identify and measure pressure changes at different locations by detecting reflections at their respective unique wavelengths.
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 system achieves accurate, cost-effective, and robust pressure change detection with reduced downtime, enabling flexible operation and precise determination of pressure change positions and courses, facilitating timely maintenance decisions.
Implementation Method 1
Each Fibre Bragg Grating is active in its particular wavelength range within the electromagnetic spectrum and reflects a certain narrow wavelength band, within the particular wavelength range, depending on parameters like temperature, pressure, strain and indices of refraction. The reflected narrow wavelength band has a peak at the Bragg wavelength.
Implementation Method 2
a method for determination of pressure changes of an optical fibre having Fiber Bragg Grating (FBG) patterns provided in at least one portion of said optical fibre, by means of the effect the pressure change has on the wavelength reflected by the FBG
Data Source
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AI summary
The invention relates to a method for determining pressure changes of an optical fibre (250) having Fiber Bragg Grating (FBG) patterns provided in at least one portion (Portion 1) of said optical fibre (250), said optical fibre (250) being connected between a first detector arrangement (210) and a second detector arrangement (220), the method comprising the steps of: - emitting (s410) light into said optical fibre (250) in a first direction (D1) from said first detector arrangement (210), receiving reflections from said (FBG) patterns of such emitted light by said first detector arrangement (210), and processing said reflections for determining a current pressure change related to said optical fibre (250); - on the basis of predetermined criteria, emitting (s440) light into said optical fibre (250) in an opposite, second, direction (D2) from said second detector arrangement (220), receiving reflections from said (FBG) patterns of such emitted light by said second detector arrangement (220), and processing said reflections for determining a current pressure change related to said optical fibre (250). The invention relates also to a computer program product comprising program code (P) for a computer (233; 243; 253; 500) for implementing a method according to the invention. The invention relates also to a system (289) for determining pressure changes of an optical fibre (250). The invention also relates to a platform (100) being equipped with the system (289).