Optical Fiber Fabry-Perot Sensor Demodulation System
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Solution Overview
Problem
Existing demodulation systems for optical fiber Fabry-Perot sensors face challenges in achieving both high speed and accuracy, particularly when measuring dynamic changes in physical quantities that result in inflection points in interference fringes.
Innovation Solution
The proposed demodulation system combines the fringe counting method and intensity demodulation method, utilizing two beams with a 90-degree phase difference for detection. This approach allows for accurate judgment of inflection points and expands the demodulation range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intensity demodulation method is used, then demodulation speed is improved and cost is reduced, but measurement precision deteriorates due to inability to accurately judge inflection points
Solution Approach 1:
The patent transforms the one-dimensional intensity measurement into a two-dimensional phase-space measurement by introducing a second beam with 90-degree phase difference. This dimensional transformation allows unique determination of cavity length variation by combining information from both beams, enabling accurate inflection point judgment while maintaining high demodulation speed.
Solution Approach 2:
The patent introduces an auxiliary beam (second beam with 90-degree phase difference) as an intermediary measurement channel. This auxiliary beam provides additional information that mediates the ambiguity in inflection point judgment, allowing accurate determination of cavity length variation without sacrificing demodulation speed.
2Adaptability or versatility
If intensity demodulation method is used, then demodulation range is improved, but measurement precision deteriorates when physical quantity changes back and forth
Solution Approach 1:
By measuring both the original beam and the 90-degree phase-shifted beam, the system creates a two-dimensional measurement space that uniquely identifies cavity length variations regardless of direction or range. This dimensional enhancement allows the system to maintain high precision for dynamic back-and-forth changes while preserving the wide demodulation range capability.
3Measurement precision
If wavelength demodulation method is used, then measurement precision is improved, but productivity deteriorates due to slow speed and high cost
Solution Approach 1:
The patent replaces the complex wavelength-based measurement system (requiring tunable lasers or spectrometers) with a simplified intensity-based interferometric system. By using two intensity measurements with known phase relationship, the system achieves wavelength-level precision without the speed and cost penalties of wavelength scanning methods.
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 combination ensures both fast demodulation speed and high accuracy, enabling precise measurement of physical quantities that change dynamically, and expands the application scenarios of the optical fiber Fabry-Perot sensor.
Implementation Method 1
the light signal received by the F-P sensor undergoes multi-beam interference in its cavity
Implementation Method 2
a first optical assembly configured to shape the interference light into a linear first interference fringe pattern; a second optical assembly configured to form a second interference fringe pattern
Implementation Method 3
a first detector provided in an light path downstream of the second optical assembly and configured to receive a first light signal to form a first light signal curve; a second detector provided in the light path downstream of the second optical assembly and configured to receive a second light signal
Data Source
AI summary
A demodulation system for optical fiber Fabry-Perot sensor, including: a light source; a Fabry-Perot sensor; a coupler; a first optical component configured to shape interference light into a linear first interference fringe pattern; a second optical assembly configured to form a second interference fringe pattern; a first detector configured to receive a first light signal to form a first light signal curve; a second detector configured to receive a second light signal to form a second light signal curve; a data collection device configured to receive the first light signal curve from the first detector to generate a first light intensity curve, and receive the second light signal curve from the second detector to generate a second light intensity curve; and a processor configured to calculate a cavity length variation of the Fabry-Perot sensor on the basis of the first light intensity curve and the second light intensity curve.