Optic Fiber Distributed Temperature Sensor with Self-Correction
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Solution Overview
Problem
Existing optical fiber distributed temperature sensor systems face challenges in accurately measuring temperature due to incorrectness in intensity distribution caused by wavelength differences and physical disturbances, requiring additional light sources and detectors for correction.
Innovation Solution
An optical fiber distributed temperature sensor system with an automatic correction function using one light source and one optical detector, employing a reflecting means and Raman filter to isolate and amplify anti-stokes Raman scattering signals, which allows for temperature measurement along the optical fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sources and detectors are used to correct for differential attenuation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses the stokes light signal as a feedback reference to compensate for differential attenuation. By measuring the ratio of anti-stokes to stokes light intensities, the system automatically corrects for wavelength-dependent losses without requiring additional correction instruments, thus maintaining measurement precision while avoiding increased device complexity
Solution Approach 2:
A single laser diode light source performs multiple functions: it generates both the anti-stokes light for temperature measurement and the stokes light for differential attenuation correction. Similarly, the optical detector detects both signal types, eliminating the need for separate correction detectors and reducing overall system complexity
2Measurement precision
If wavelength difference between stokes and anti-stokes light is compensated, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system automatically compensates for wavelength differences by using the stokes light signal as a reference feedback mechanism. The ratio of anti-stokes to stokes intensities provides real-time compensation for differential attenuation, eliminating the need for manual wavelength calibration or additional correction systems
Solution Approach 2:
The stokes light acts as an intermediary reference signal that mediates between the anti-stokes light and the detector. By measuring both signals and computing their ratio, the system eliminates wavelength dependency without requiring separate correction instruments or complex calibration procedures
3Measurement precision
If physical disturbances in optical fiber are accounted for, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The stokes light signal serves as a feedback indicator of physical disturbance conditions. By monitoring the ratio of anti-stokes to stokes light intensities, the system automatically adapts to bending, tension, compression, and contamination effects without requiring separate sensors or correction mechanisms
Solution Approach 2:
The system uses its own stokes light signal to correct for physical disturbances affecting the anti-stokes signal. This self-correction mechanism eliminates the need for external correction systems or additional disturbance sensors, maintaining measurement precision while keeping the device simple
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
Enables accurate and cost-effective temperature measurement by overcoming wavelength differences and physical obstacles, using only one light source and one detector, and effectively removing measurement errors caused by differential attenuation.
Implementation Method 1
a small amount of a Raman scattering light having a wavelength shifted by Raman scattering is also included in the back scattering light. The Raman scattering light contains a stokes light whose wavelength is shifted toward a long wavelength and an anti-stokes light whose wavelength is shifted toward a short wavelength with respect to the incident light. The Raman scattering occurs when the light entered into the optical fiber collides with Silica molecules. Since the amount of motion of the Silica molecules is changed depending on a temperature, the scattering amount depending on the temperature is changed.
Implementation Method 2
a reflecting means 125 provided at one end of the measured optical fiber 120, for reflecting the optical signal transmitted through the measured optical fiber 120, along the measured optical fiber 120
Implementation Method 3
a Raman filter 130 connected to the optical circulator 115, for separating and passing only an anti-stokes Raman scattering optical signal among the optical signals separated and transmitted from the optical circulator 115
Implementation Method 4
an optical detector 135 connected to the Raman filter 130, for converting the anti-stokes Raman scattering optical signal into an electrical signal that can be signal processed
Data Source
AI summary
The present invention is effective in that automatically corrected temperature can be measured using one light source and one optical detector.