Fabry-Perot Sensor for High-Precision Inclination Measurement
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Solution Overview
Problem
Existing inclination sensors, such as FBG sensors, have limited accuracy and sensitivity due to resistance issues, which affect their measuring capabilities, especially in measuring large angles and under varying conditions like temperature changes.
Innovation Solution
A Fabry-Perot sensor design that uses a mass block and optic fibers with a non-contact reflecting surface to measure inclination by detecting changes in the cavity length, allowing for high precision and resistance-free tilting angle measurement, with options for flexible or rigid connections and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If FBG sensors are used for measuring inclination, then the sensor structure is simple, but the measurement precision is limited to about 5 degrees with accuracy in the order of minutes
Solution Approach 1:
The patent replaces the mechanical strain-based FBG sensing mechanism with an optical Fabry-Perot interferometry system. The F-P cavity uses optical interference patterns to measure inclination, eliminating the need for mechanical strain transmission and achieving much higher precision (0.001°) while maintaining structural simplicity through optical fiber integration.
Solution Approach 2:
The patent changes the measurement parameter from strain-induced wavelength shift in FBG to optical path difference in the F-P cavity. By using the relationship between cavity length change and inclination angle (ΔL = L·sin(θ)), the system achieves higher measurement precision while maintaining a simple structural design.
2Device complexity
If electric sensors or FBG sensors are used, then the sensor structure is available, but the measuring sensitivity is considerably reduced due to resistance issues
Solution Approach 1:
The patent eliminates electrical resistance issues by replacing electrical sensing mechanisms with optical Fabry-Perot interferometry. The optical system measures inclination through changes in the optical path length of the F-P cavity, completely avoiding resistance-related sensitivity losses and achieving high measuring sensitivity without electrical components.
Solution Approach 2:
The patent introduces an optical field as an intermediary between the mechanical inclination and the measurement signal. The F-P cavity converts mechanical displacement into optical interference patterns, providing a high-sensitivity measurement mechanism that avoids the limitations of direct electrical or mechanical sensing.
3Device complexity
If contact-based sensing is used, then the sensor can be simple in structure, but the service life is reduced due to wear
Solution Approach 1:
The patent replaces mechanical contact-based sensing with non-contact optical measurement. The F-P cavity uses optical interference to detect displacement without physical contact between the sensing element and the measured object, eliminating wear and significantly extending service life while keeping the structure simple.
Solution Approach 2:
The patent uses optical fields as an intermediary to transfer measurement information without physical contact. The F-P cavity allows light to pass through and detect displacement optically, avoiding mechanical contact and wear while maintaining structural simplicity.
4Ease of operation
If strain-based sensing is used, then the sensor can measure inclination, but the resistance affects the measuring sensitivity and accuracy
Solution Approach 1:
The patent replaces strain-based electrical sensing with optical Fabry-Perot interferometry. The F-P cavity measures inclination through optical path length changes rather than mechanical strain, eliminating resistance effects and achieving high measuring sensitivity and accuracy while maintaining ease of operation.
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
The sensor achieves high accuracy up to 0.001°, is resistant to temperature variations, and has a long service life due to non-contact operation, making it suitable for long-term monitoring in harsh conditions.
Implementation Method 1
a Fabry-Perot cavity is formed between the reflecting surface disposed at one end of the mass block and the end of the optic fiber. The change of cavity length can be measured in accordance with the Fabry-Perot principle
Implementation Method 2
The end of the first fiber provided with the first reflecting end face is directly facing to the first reflecting surface, thus the first F-P cavity is formed between the first reflecting surface and the first reflecting end face
Implementation Method 3
the line between the center of gravity of the mass block and the connecting point on the top plate is perpendicular to the horizontal plane
Data Source
AI summary
A Fabry-Perot sensor for measuring an inclination. The sensor is fixed on a static detected object, where a mass block is flexibly connected to a top plate, thus the line between the center of gravity of the mass block and the connecting point on the top plate is perpendicular to the horizontal plane. This creates a Fabry-Perot cavity between a reflecting surface disposed at one end of the mass block and the end of an optic fiber. When the detected object is tilted, the line between the center of gravity of the mass block and its connecting point on the top plate remains perpendicular and the F-P cavity length will have a variation in length. The change of cavity length is measured in accordance with the Fabry-Perot principle, thereby the tilting angle, which is the inclination of the detected object, of the mass block is measured.