Magnetostrictive Fiber Optic Magnetic Field Detector
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Solution Overview
Problem
Current magnetic detection methods for geological surveys and other applications are expensive and prone to failure in harsh environments, requiring multiple detectors and being unable to provide continuous, reliable data over long distances or in conditions unsuitable for precision instruments.
Innovation Solution
A fibre optic system with magnetically responsive material, where the optical fibre is mechanically coupled to a material whose dimensions change with the applied magnetic field, allowing for distributed sensing of magnetic fields through backscattered radiation analysis, enabling continuous and reliable detection along its length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual magnetic detectors are lowered into bore holes to measure magnetic fields at different depths, then magnetic field detection is achieved, but the cost increases and each detector requires separate connection to the surface
Solution Approach 1:
The optical fibre is segmented into multiple sensing sections along its length, with each section capable of detecting magnetic fields independently. This allows distributed sensing throughout the bore hole without requiring separate connections for each detection point, as the entire fibre acts as a distributed array of sensors.
Solution Approach 2:
The optical fibre serves multiple functions: it acts as both the transmission medium for interrogating radiation and the sensing element for magnetic field detection. The magnetically responsive material coating the fibre enables it to function as a magnetic sensor while maintaining its role as an optical transmission medium, eliminating the need for separate detection equipment at each depth.
2Measurement precision
If many detectors are placed at short intervals down long holes to achieve fine structured tomography, then measurement precision improves, but the cost and difficulty of deployment increase
Solution Approach 1:
The optical fibre is divided into numerous sensing sections along its length, with each section capable of independent magnetic field detection. This segmentation allows fine structured tomography to be achieved without deploying multiple separate detectors, as the single fibre provides distributed sensing throughout the entire bore hole length.
Solution Approach 2:
The magnetically responsive material is coated along the entire length of the optical fibre, creating a continuous distribution of sensing elements. This copying of magnetic sensing capability along the fibre length allows numerous detection points to be achieved without physically deploying multiple separate detectors, significantly easing deployment while maintaining precision.
3Reliability
If conventional magnetic detectors are used in harsh down-hole environments, then magnetic field measurement is achieved, but the detectors are prone to failure due to unsuitable conditions
Solution Approach 1:
The patent replaces conventional mechanical/electronic magnetic detectors with an optical sensing system. The optical fibre with magnetically responsive material coating detects magnetic fields through optical means (interrogating radiation and backscattered radiation analysis), eliminating the need for electronic sensors that are prone to failure in harsh down-hole environments.
Solution Approach 2:
The magnetically responsive material changes its physical parameters (dimensions) in response to applied magnetic fields. This parameter change is detected optically through the fibre, allowing the system to sense magnetic field strength variations without requiring the detection equipment itself to withstand harsh environmental conditions, as the sensing occurs through material property changes rather than electronic measurements.
4Device complexity
If discrete magnetic detectors are used instead of continuous sensing, then device complexity is reduced, but continuous data for 3D mapping cannot be obtained
Solution Approach 1:
The optical fibre provides continuous sensing along its entire length, with the magnetically responsive material coating enabling continuous detection of magnetic field variations. This continuity allows for uninterrupted data collection throughout the bore hole, enabling 3D mapping and tomography without the gaps that would result from discrete detector arrangements.
Solution Approach 2:
The optical fibre serves as both the transmission medium and the continuous sensing element. Its dual function allows it to provide continuous magnetic field data along its entire length while maintaining system simplicity, as the same fibre that transmits optical signals also serves as the distributed magnetic sensor array.
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 solution provides continuous, reliable magnetic field detection over long distances, even in challenging environments, using existing distributed acoustic sensing techniques adapted for magnetic field detection, improving data quality and reducing costs by using robust optical fibres and magnetostrictive materials.
Implementation Method 1
a material whose dimensions vary dependent on the applied magnetic field
Implementation Method 2
interrogate a first length of optical fibre with interrogating radiation, detect radiation backscattered from said optical fibre and analyse said detected radiation to provide distributed sensing indicative of mechanical disturbances of said optical fibre
Data Source
AI summary
There is provided a system (100) for magnetic field detection, comprising a fiber optic interrogator (104) adapted to interrogate a first length of optical fiber (102) with interrogating radiation, detect radiation backscattered from said optical fiber and analyze said detected radiation to provide distributed sensing indicative of mechanical disturbances of said optical, wherein the optic fiber is mechanically coupled to a material whose dimensions vary dependent on applied magnetic field. Changes in dimensions of the optic fiber as can be detected by virtue of changes in back-scattering of light from said fiber using the principles of fiber optic distributed acoustic sensing.