Distributed Optical Fibre Sensor Coherent Rayleigh Noise Reduction
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Solution Overview
Problem
Distributed optical fibre sensors face challenges due to variations in sensing fibre properties over time, such as degradation and environmental influences, affecting performance in measuring environmental parameters, necessitating the ability to monitor and adjust operating parameters to maintain optimal performance.
Innovation Solution
A method and apparatus for determining an OTDR trace using wavelength-tuned probe light sources with temporal/spatial oversampling to reduce coherent Rayleigh noise, allowing for integrated measurement of environmental parameters and fibre properties, employing narrowband probe light pulses to minimize hardware costs and improve measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coherent Rayleigh noise is used for measuring environmental parameters, then measurement capability is provided, but noise reduces measurement precision and fibre property monitoring accuracy
Solution Approach 1:
The patent segments the probe light pulses into two distinct subsets: a first subset for measuring environmental parameters using coherent Rayleigh noise, and a second subset for determining fibre properties by minimizing coherent Rayleigh noise. This segmentation allows each subset to be optimized for its specific purpose, resolving the contradiction between needing coherent noise for environmental measurements and needing minimal noise for fibre property monitoring.
Solution Approach 2:
The patent applies different quality characteristics to different parts of the probe light signal. The first subset of pulses is configured with properties suitable for extracting environmental parameter information through coherent Rayleigh noise, while the second subset is configured with properties that minimize coherent Rayleigh noise to enable accurate fibre property monitoring. This local differentiation of signal properties resolves the measurement precision issue.
2Measurement precision
If multiple separate optical systems are used for OTDR trace measurement and parameter measurement, then measurement capability is improved, but device complexity and hardware costs increase
Solution Approach 1:
The patent implements a single multi-functional optical measurement system that can perform both environmental parameter measurement and fibre property monitoring (OTDR trace) using one probe light source and one set of optical components. The probe light source generates both subsets of pulses, and the same optical detection system processes both types of measurements, eliminating the need for separate optical systems and reducing device complexity.
Solution Approach 2:
The patent merges the functionality of separate optical measurement systems into a unified system. The single probe light source combines environmental parameter measurement and fibre property monitoring capabilities, and the optical detection system combines processing for both measurement types. This merging reduces hardware complexity and costs while maintaining measurement precision.
3Device complexity
If probe light pulses are used for both environmental measurement and fibre property monitoring, then hardware costs are reduced, but coherent Rayleigh noise interferes with fibre property monitoring
Solution Approach 1:
The patent segments the probe light pulses into two subsets with different characteristics. The first subset is optimized for environmental parameter measurement where coherent Rayleigh noise is beneficial, while the second subset is optimized for fibre property monitoring where coherent Rayleigh noise should be minimized. This segmentation allows a single hardware system to perform both functions without noise interference.
Solution Approach 2:
The patent employs periodic or sequential transmission of different pulse subsets. The system alternates between transmitting the first subset of pulses for environmental measurement and the second subset for fibre property monitoring. This periodic action allows the same hardware to perform both measurements without simultaneous noise interference, maintaining measurement precision while reducing hardware complexity.
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 accurate and efficient monitoring of fibre properties and environmental parameters, reducing coherent Rayleigh noise, and facilitating automatic control of the sensor to compensate for changes, thereby maintaining optimal performance.
Implementation Method 1
detecting characteristics of the probe light following elastic or inelastic backscatter from the native material of the sensing optical fibre
Implementation Method 2
techniques such as the detection and use of Brillouin backscatter in determining temperature and strain
Implementation Method 3
receiving backscattered light from the sensing optical fibre at an optical detector
Implementation Method 4
detection of coherent Rayleigh noise arising from small variations in refractive index along the sensing optical fibre
Data Source
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AI summary
A method of operating a distributed optical fibre sensor to measure one or more parameters of an environment as functions of position along a sensing optical fibre passing through the environment determines, measures or calculates an OTDR trace or attenuation profile of a sensing optical fibre in a distributed optical fibre sensor. The OTDR trace is to monitored to provide an indicia of properties of the sensing optical fibre in order to determine if the performance of the distributed optical fibre sensor in accurately measuring the desired environmental parameters is compromised. This allows adjustment of operation parameters of the distributed optical fibre sensor to maintain the performance at acceptable levels, or to automatically control the distributed optical fibre sensor in order to at least partly compensate for the changing properties. A distributed optical fibre sensor having such capability is also disclosed.