Interferometric Optical Fiber Sensor with Equal Path Lengths
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Solution Overview
Problem
Interferometric optical fiber sensors face challenges in reducing environmental influences and increasing detection sensitivity due to complex structures and high costs associated with temperature-compensating fibers and multiple components for light splitting and delaying.
Innovation Solution
The system employs a simple structure with equal optical lengths for measurement and reference paths, using first and second delay lines and a modulation unit, often a coil, to set phases and reduce environmental influences, allowing for secure measurement of light modulation while eliminating ghost signals and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-compensating fibers are used to suppress temperature drifts, then measurement stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses ordinary optical fibers with equal optical lengths for both measurement and reference paths, making both paths homogeneous in terms of material and length. This eliminates the need for special temperature-compensating fibers while maintaining measurement stability through differential measurement that cancels out common-mode temperature effects.
2Measurement precision
If multiple components are used for splitting light, imparting delay, and combining light, then interferometric measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of light splitting, delaying, and combining into a single integrated optical path configuration. The measurement and reference paths share common components and are configured to have equal optical lengths, eliminating the need for separate delay fibers and reducing the number of coupling components while maintaining interferometric measurement capability.
3Extent of automation
If unequal optical lengths are used in measurement and reference paths, then phase modulation is achieved, but environmental susceptibility increases
Solution Approach 1:
The patent configures equal optical lengths in both measurement and reference paths from the outset, establishing a balanced interferometric system. Phase modulation is then achieved through the measurement process itself rather than through path length differences, which prevents environmental factors from causing differential drift between paths while maintaining the ability to modulate and detect phase changes.
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 configuration enables secure measurement of light modulation by reducing environmental influences and improving detection sensitivity through equal delay times and common optical paths, resulting in higher measurement accuracy and reduced complexity.
Implementation Method 1
interferometric optical fiber sensor system... measurement unit for measuring modulation of the measurement light and the reference light according to light combined by the second coupler
Implementation Method 2
modulation unit for modulating with a stress exerted thereon the measurement light and the reference light
Data Source
AI summary
An interferometric optical fiber sensor system comprises a light source, a first coupler optically connected to the light source, a first optical path for inputting measurement light, a second optical path for inputting reference light, a second coupler for combining the first and second optical paths together, a photodetector for measuring modulation of the measurement light and the reference light, and a coil for modulating with a stress exerted thereon the measurement light and the reference light. The first optical path has an optical length equal to that of the second optical path. The first optical path has a first delay line, while the second optical path has a second delay line. The coil is disposed between the first delay line and the second coupler and between the second delay line and the first coupler.