Fiber Bragg Grating Time-of-Flight Overheat Localization
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Solution Overview
Problem
Existing fiber Bragg grating (FBG) interrogation systems face limitations in interrogating large arrays with dense spacing and overlapping reflection spectra, making it difficult to accurately detect small temperature or strain changes due to spectral shadowing and crosstalk, especially in harsh environments.
Innovation Solution
A pulse-based interrogation method using a specific wavelength sweep and time-of-flight analysis to construct a two-dimensional map, allowing simultaneous detection of overheat conditions and their locations by applying a reflection intensity triggering threshold and density measure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectral analysis methods are used to detect temperature changes in FBG arrays, then measurement capability is provided, but spectral shadowing and crosstalk mask small spectrum changes making detection inaccurate
Solution Approach 1:
The patent replaces traditional spectral analysis methods with time-domain pulse propagation analysis. Instead of analyzing overlapping reflection spectra in the frequency domain, the system uses time-of-flight measurements of optical pulses traveling through the fiber array, substituting spectral domain analysis with temporal domain analysis to eliminate spectral shadowing and crosstalk issues
Solution Approach 2:
The patent changes the measurement parameter from spectral wavelength to time-of-flight. By measuring the time it takes for optical pulses to propagate through different positions in the FBG array rather than analyzing reflection spectra, the system transforms the detection parameter to avoid spectral overlapping problems while maintaining temperature measurement capability
2Quantity of substance
If FBG arrays with dense spacing are used to increase sensor quantity, then monitoring coverage is improved, but spectral overlapping increases making individual sensor detection difficult
Solution Approach 1:
The patent substitutes spectral domain measurement with time-domain pulse propagation measurement. By injecting optical pulses and measuring their arrival times at different positions along the fiber array, the system can resolve individual sensor responses temporally even when their spectral reflections overlap, enabling detection of densely spaced FBGs
Solution Approach 2:
The patent uses periodic injection of optical pulses through the FBG array to sequentially excite and measure each grating's response in the time domain. This periodic pulsing creates distinct temporal signatures for each sensor position, allowing individual sensor detection despite dense spatial spacing and spectral overlapping
3Device complexity
If traditional interrogation methods are used, then system simplicity is maintained, but processing time increases and false alarms occur
Solution Approach 1:
The patent replaces complex spectral analysis processing with simpler time-domain pulse propagation analysis. By measuring pulse arrival times and comparing them against reference values, the system reduces computational complexity while simultaneously decreasing processing time and eliminating false alarms associated with spectral interpretation
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
This method enables efficient and accurate detection of overheat conditions and their locations in fiber optic networks, reducing processing time and false alarms while identifying low overheat temperatures.
Implementation Method 1
fiber Bragg grating (FBG) technologies
Implementation Method 2
time-of-flight analysis to construct a two-dimensional map
Data Source
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AI summary
A method for detecting and determining a location of an overheat condition includes producing a narrowband optical signal with a laser source and optical pulse generator. The optical signal is sent into the optical fiber. A plurality of reflected optical signals is received. Reflection intensities are detected using a photodetector. The reflection intensities are compared with a triggering threshold. Response times of the reflected optical signals are recorded whenever the reflection intensity of the optical signals is greater than the triggering threshold. The narrowband optical signal is adjusted to another wavelength. An anomaly reflected optical signal is identified using a characteristic of the timings obtained through a range of wavelengths. The location of the overheat condition recorded response times is calculated. The location and existence of the overheat condition is communicated.