Optical Interferometer Gap Minimization and Magnetic Shielding
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Solution Overview
Problem
Conventional optical current measurement technologies, such as those using the Faraday effect, face accuracy issues due to temperature fluctuations and imperfections in quarter wave plates and magnetic fiber sensitivity, leading to errors in current measurement.
Innovation Solution
An improved optical interferometer design with a minimized gap between the quarter wave plate and mirror, and a magnetic shield to reduce magnetic field interference, ensuring accurate current measurement by minimizing the magnetic field passing through the gap and shielding components from external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gap exists between the quarter wave plate and mirror in the optical fiber, then the device is easier to manufacture and assemble, but magnetic field interference increases leading to reduced measurement precision
Solution Approach 1:
The patent introduces a magnetic shield that converts the harmful magnetic field interference into a beneficial solution by actively compensating for the field leakage caused by the gap. The magnetic shield material absorbs and redirects magnetic field lines, transforming the potential source of error into an opportunity for enhanced measurement accuracy through controlled magnetic field management.
Solution Approach 2:
The magnetic shield acts as an intermediary element between the optical fiber gap and the external magnetic field. This intermediate component absorbs the magnetic field interference that would otherwise directly affect the light propagation through the gap, allowing the gap to remain for manufacturing ease while preventing magnetic field leakage from degrading measurement precision.
2Measurement precision
If the optical fiber extends further around the conductor to improve measurement accuracy through increased path length, then the magnetic field integration improves, but the device size and complexity increase
Solution Approach 1:
The patent combines multiple optical fiber paths into a unified sensing configuration where the optical fiber is wrapped around the conductor in a systematic pattern that maximizes magnetic field integration. By merging the fiber paths and using a single continuous fiber configuration with strategic routing, the system achieves enhanced measurement accuracy without proportionally increasing device complexity.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement of the optical fiber around the conductor, transitioning from a simple linear path to a multi-dimensional winding configuration. This dimensional approach allows the fiber to integrate magnetic field effects more effectively by sampling the field from multiple spatial perspectives, improving measurement accuracy without requiring excessive fiber length or complex assembly procedures.
3Reliability
If conventional Hall effect technology is used for high current measurement, then reliable measurement is achieved, but the equipment becomes expensive, large, and heavy
Solution Approach 1:
The patent replaces the conventional Hall effect sensor with an all-optical measurement system that uses light propagation through optical fiber to detect magnetic field effects. This substitution eliminates the need for heavy electronic sensors and complex magnetic shielding structures, significantly reducing the weight and size of the measurement equipment while maintaining reliability through the Faraday effect-based optical detection method.
Solution Approach 2:
The patent changes the fundamental measurement parameter from electrical voltage output (Hall effect) to optical phase or polarization changes (Faraday effect). This parameter transformation allows for a more compact and lighter system design, as optical fibers and their associated components are significantly lighter and smaller than conventional Hall sensors and their required magnetic shielding and electronic signal conditioning infrastructure.
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 design enhances the accuracy of current measurement by reducing magnetic field interference and temperature-related errors, achieving improved scaling and stability in current sensing.
Implementation Method 1
Such devices are interferometers that utilize the Faraday effect, in which there is an interaction between light and the magnetic field produced around the conductor, to measure current
Implementation Method 2
The quarter wave plate defines the beginning of the sensing region, where the beams are polarized, and the end of the sensing region for the returning light
Implementation Method 3
the sensing path is terminated in a mirror, at which a RHCP beam is converted to a LHCP beam upon reflection, and vice versa
Data Source
Figure 1
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Figure 3~5
AI summary
An optical interferometer used to measure the current in a conductor, where the gap between the mirror and the quarter wave plate is minimized, and the gap is shielded magnetically. Additionally, at least the modulator is shielded, and preferably the case containing many of the components, such as the integral number of turns of optical fiber in a coil, is magnetically shielded. By shielding the components, and reducing the gap between the quarter wave plate and the mirror, the error in the current measurement is substantially reduced.