Hybrid Fiber Optic Sensing System for High Speed Strain Measurement
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Solution Overview
Problem
Current fiber optic strain sensing technologies face limitations in achieving high spatial resolution and high frequency measurements simultaneously, with WDM systems offering high sample rates but limited spatial resolution, and OFDR systems providing high spatial resolution but low sample rates, making them unsuitable for capturing strain data during high-frequency events.
Innovation Solution
A hybrid fiber optic sensing system that integrates WDM and OFDR fiber Bragg gratings within a single fiber, utilizing different light sources and spacings to achieve both high spatial resolution and high frequency measurements, allowing for real-time data processing and integration with conventional analytics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If WDM fiber Bragg gratings are used, then high sample rates (kHz ranges) are achieved, but spatial resolution is limited due to wavelength range constraints
Solution Approach 1:
The patent combines WDM and OFDR technologies into a single hybrid fiber optic sensing system. The WDM component provides high sample rate measurements at discrete locations, while the OFDR component provides high spatial resolution through continuous grating. By merging these two approaches in a single fiber, the system achieves both high productivity (sample rate) and high measurement precision (spatial resolution) simultaneously.
Solution Approach 2:
The hybrid fiber optic sensor serves multiple functions: it performs both WDM-based discrete point measurements and OFDR-based continuous spatial measurements through a single integrated system. This multi-functionality allows the same sensor to provide both high sample rate data for dynamic events and high spatial resolution data for detailed strain distribution analysis.
2Measurement precision
If OFDR systems are used, then high spatial resolution is achieved with thousands of gratings per fiber, but sample rate is limited to less than 100 Hz
Solution Approach 1:
The patent merges OFDR and WDM technologies in a hybrid system where the OFDR component provides high spatial resolution measurements and the WDM component provides high sample rate measurements. This combination resolves the limitation of low sample rate in pure OFDR systems while maintaining the high spatial resolution capability.
Solution Approach 2:
The sensing fiber is segmented into different functional regions: densely spaced OFDR gratings for high spatial resolution and sparsely spaced WDM gratings for high sample rate measurements. This segmentation allows each technology to operate in its optimal performance regime while contributing to the overall system capabilities.
3Quantity of substance
If multiple FBGs are multiplexed in WDM system, then discrete location measurements are obtained, but the number of FBGs is limited by wavelength range and source bandwidth
Solution Approach 1:
The hybrid system merges WDM and OFDR approaches, allowing the WDM component to provide multiple discrete measurement points and the OFDR component to provide continuous spatial coverage with thousands of effective measurement points, thus overcoming the limitation on the number of multiplexed FBGs.
Solution Approach 2:
The system transitions from the wavelength dimension used in WDM to the spatial/position dimension used in OFDR. By utilizing the OFDR dimension, the system can accommodate thousands of measurement points along the fiber length without being constrained by the limited wavelength multiplexing capacity of WDM.
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 hybrid system enables the capture of high spatial resolution and high frequency strain data in real-time, maintaining the lightweight and low-profile characteristics of modern systems, suitable for applications requiring precise strain monitoring during extreme conditions.
Implementation Method 1
When incorporated into an optical fiber, an FBG reflects particular wavelengths of light based on its Bragg wavelength, an inherent characteristic of the FBG for a given mode. Strain or certain other forces acting on the fiber and thus on the FBG will alter the reflected wavelength.
Implementation Method 2
their positions and characteristics along the fiber are detected by measuring the beat frequency of an individual grating's reflection against the reflection from a reference arm of an interferometer having a known length
Data Source
AI summary
The present invention is an improved fiber optic sensing system (FOSS) having the ability to provide both high spatial resolution and high frequency strain measurements. The inventive hybrid FOSS fiber combines sensors from high acquisition speed and low spatial resolution Wavelength-Division Multiplexing (WDM) systems and from low acquisition speed and high spatial resolution Optical Frequency Domain Reflection (OFDR) systems. Two unique light sources utilizing different wavelengths are coupled with the hybrid FOSS fiber to generate reflected data from both the WDM sensors and OFDR sensors operating on a single fiber optic cable without incurring interference from one another. The two data sets are then de-multiplexed for analysis, optionally with conventionally-available WDM and OFDR system analyzers.