Interference Optical Magnetic Field Sensor Distance Independence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing interference type optical magnetic field sensors are limited in accurately measuring magnetic fields around conductors due to dependence on the distance between the sensor and the conductor, and they struggle to measure high-frequency currents, with ferrite magnetic yokes restricting measurable frequency to about 1 MHz.
Innovation Solution
An interference type optical magnetic field sensor device is designed with a pair of magnetic field sensor elements and an optical system that includes a light emitter, circulator, half-wave plate, and polarization-maintaining fibers, allowing for independent measurement of magnetic fields regardless of distance and enabling the detection of high-frequency currents by separating and processing polarized light components to generate a detected signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic field sensor element is disposed on one side of the current path, then the device structure is simple, but the measured magnetic field amount varies by distance and measurement accuracy deteriorates
Solution Approach 1:
The single sensor element is segmented into a pair of magnetic field sensor elements (50A, 50B) disposed symmetrically across the current path. This segmentation allows the system to measure magnetic fields at multiple positions simultaneously, enabling accurate determination of current-related magnetic fields while canceling out distance-dependent variations through differential measurement.
Solution Approach 2:
The patent employs asymmetric measurement configuration where sensor elements are positioned at specific symmetric locations relative to the current path. This asymmetric arrangement with respect to the current flow direction enables the system to distinguish between magnetic fields generated by the current of interest and those from external sources, improving measurement accuracy.
2Area of stationary object
If a magnetic yoke is used to measure magnetic field around the conductor, then the measurement coverage is improved, but the measurable frequency is limited to about 1 MHz due to ferrite material properties
Solution Approach 1:
The patent extracts and removes the ferrite magnetic yoke from the sensor structure, replacing it with a non-magnetic support structure. This extraction eliminates the frequency-limiting property of ferrite material while maintaining the structural function of supporting the sensor elements, thereby enabling measurement of high-frequency currents up to GHz range.
Solution Approach 2:
The patent substitutes the magnetic yoke structure with a non-magnetic mechanical support structure. This replacement eliminates the magnetic material's frequency constraints while preserving the geometric arrangement needed for magnetic field measurement, allowing the optical sensor to operate at high frequencies without the 1 MHz limitation of ferrite materials.
3Stability of the object's composition
If the sensor is fixed at a specific position, then the device stability is improved, but the magnetic field generated around the conductor cannot be accurately measured due to distance dependence
Solution Approach 1:
The patent merges the outputs from multiple magnetic field sensor elements through optical combination in the interferometric detection system. By combining the optical signals from sensors at different positions, the system achieves differential measurement that cancels out distance-dependent variations while maintaining the stability benefits of fixed sensor positions.
Solution Approach 2:
The interferometric detection system provides feedback through phase difference measurement, allowing the system to compensate for positional variations and extract accurate current-related magnetic field information. The optical phase detection mechanism feedbacks the magnetic field information, enabling accurate measurement independent of exact sensor positioning.
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 accurate measurement of magnetic fields independent of distance and allows for the measurement of high-frequency currents, improving the accuracy and frequency range compared to traditional sensors, including those with ferrite magnetic yokes.
Implementation Method 1
having a light transmissive, changing the phase of transmitted light in accordance with the magnetic field
Implementation Method 2
a light emitter emitting a first linearly polarized light
Implementation Method 3
an optical path including a first optical path propagating the first linearly polarized wave and the fourth linearly polarized wave, and a second optical path propagating the second linearly polarized wave and the third linearly polarized wave
Implementation Method 4
converting to the electrical signal
Data Source
AI summary
A magnetic field sensor element 1 includes a light emitter 10 emitting a first linearly polarized light, a first optical element 20 emitting a first linearly polarized wave and the second linearly polarized wave in response to a first linearly polarized light incident, and emitting a second linearly polarized light in response to a third linearly polarized wave and the a linearly polarized wave incident, at least one pair of magnetic field sensor elements 50 capable of disposing in a predetermined magnetic field across the measured conductor, having a light transmissive, changing the phase of transmitted light in accordance with the magnetic field, and fixing a relative position therebetween, an optical path 30 including a first optical path propagating the first linearly polarized wave and the fourth linearly polarized wave, and a second optical path propagating the second linearly polarized wave and the third linearly polarized wave, and connected to the first optical element and the magnetic field sensor element, a detected signal generator 60 outputting a detected signal corresponding to the magnetic field, by receiving two components of the second linearly polarized light, and converting to the electrical signal, and an optical branching element transmitting the first linearly polarized light to the first optical element and branching the second linearly polarized light to the detected signal generator.