Series-Parallel Fabry-Perot Interferometers for Synchronous Temperature and Salinity Measurement
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Solution Overview
Problem
The sensitivity of single Fabry-Perot interferometers is limited, and they are unable to perform simultaneous temperature and salinity measurements, which is essential for advanced marine environmental monitoring.
Innovation Solution
A series-parallel structure of three Fabry-Perot interferometers is designed, where the first interferometer is insensitive to temperature and salinity, the second is sensitive to both, and the third is only sensitive to temperature, producing a vernier effect to enhance sensitivity and enable simultaneous measurement through spectral analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Fabry-Perot interferometer is used, then the device complexity is low, but the measurement precision and sensitivity are limited
Solution Approach 1:
The sensing system is divided into three independent Fabry-Perot interferometers, each with specific sensitivity characteristics. The first interferometer is insensitive to both temperature and salinity, the second is sensitive to both parameters, and the third is sensitive only to temperature. This segmentation allows each interferometer to contribute specifically to the measurement of particular parameters, enabling simultaneous temperature and salinity measurement while maintaining manageable device complexity.
Solution Approach 2:
The three interferometers work together as a unified sensing system that performs multiple measurement functions. By combining the outputs of interferometers with different sensitivity characteristics, the system achieves universal capability for simultaneous temperature and salinity measurement, transforming individual single-parameter sensors into a multi-functional measurement platform.
2Measurement precision
If a single interferometer is used, then the device complexity is low, but the sensitivity is limited
Solution Approach 1:
Three Fabry-Perot interferometers are merged into a single integrated sensing system with a series-parallel connection structure. The first interferometer connects in series with the optical fiber circulator and coupler, while the second and third interferometers connect in parallel to the coupler. This merging of multiple interferometers with different sensitivity characteristics amplifies the overall sensitivity through the vernier effect, enabling detection of subtle changes in temperature and salinity that would be imperceptible to a single interferometer.
3Adaptability or versatility
If temperature and salinity synchronous measurement is implemented, then the measurement capability is improved, but the device complexity increases
Solution Approach 1:
Each interferometer is designed with specific local quality characteristics in terms of sensitivity. The first interferometer has the quality of being insensitive to both temperature and salinity, the second has the quality of being sensitive to both parameters, and the third has the quality of being sensitive only to temperature. This differentiation of local quality across the three interferometers enables the system to simultaneously measure both parameters by combining their specific responses, achieving versatile measurement capability without requiring a completely complex redesign.
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 system achieves improved sensitivity and simultaneous temperature and salinity measurement by leveraging the vernier effect, allowing for precise data acquisition in marine environments.
Implementation Method 1
The optical fiber Fabry-Perot sensor may directly interact with seawater to produce the interference
Implementation Method 2
which may produce the optical vernier effect, improve the sensitivity by the amplification of the vernier effect
Data Source
AI summary
An optical fiber sensing system for temperature and salinity synchronous measurement is provided, which includes a broad-spectrum light source, an optical fiber circulator, a coupler, a first interferometer, a second interferometer, a third interferometer and a spectrometer; the first interferometer is insensitive to temperature and salinity; the second interferometer is sensitive to both temperature and salinity, and the third interferometer is only sensitive to temperature; light emitted by the broad-spectrum light source passes through the optical fiber circulator and enters the first interferometer; reflected light of the first interferometer passes through the optical fiber circulator and the coupler sequentially, and then enters the second and the third interferometers respectively; the reflected light of the second and the third interferometers enters the spectrometer after passing through the coupler; the temperature and the salinity to be measured are simultaneously obtained by performing spectral analysis of the reflected light entering the spectrometer.