Distributed Temperature Sensor Raman Suppression
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Solution Overview
Problem
Existing distributed temperature sensors (DTS) face limitations in accuracy due to the need to restrict incident light intensity to prevent stimulated Raman scattering, which reduces signal levels and measurement accuracy.
Innovation Solution
The implementation of fiber Bragg gratings (FBGs) in optical fibers to filter out Stokes Raman scattering, allowing for higher incident light intensity without triggering stimulated Raman scattering, enabling temperature determination based on the ratio of anti-Stokes Raman scattering to Rayleigh scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If incident light intensity is increased to improve signal levels and measurement accuracy, then temperature measurement accuracy is improved, but stimulated Raman scattering is triggered which degrades measurement accuracy
Solution Approach 1:
The patent extracts and removes the harmful Stokes Raman scattering component from the optical fiber using a filter, separating it from the anti-Stokes signal. This allows high incident light intensity to be used without the Stokes scattering interfering with temperature measurements, thus resolving the contradiction between signal strength and measurement accuracy.
Solution Approach 2:
The patent introduces a filter as an intermediary component between the light source and the detection system. This filter selectively blocks Stokes Raman scattering while allowing anti-Stokes Raman scattering to pass through, enabling the use of high incident light intensity without triggering harmful non-linear effects in the temperature measurement process.
2Reliability
If incident light intensity is restricted to prevent stimulated Raman scattering, then non-linear optical effects are avoided, but signal levels decrease and measurement accuracy is reduced
Solution Approach 1:
The patent converts the harmful Stokes Raman scattering into a beneficial filtering opportunity. By placing a filter that specifically blocks Stokes wavelengths, the system uses the presence of Stokes scattering as a means to identify and remove it, while the high incident light intensity continues to generate strong anti-Stokes signals for accurate temperature measurement.
Solution Approach 2:
The filter acts as an intermediary that selectively transmits anti-Stokes Raman scattering while blocking Stokes Raman scattering. This allows the system to maintain high incident light intensity for strong signals without the harmful effects of Stokes scattering, thereby improving both reliability and measurement precision simultaneously.
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 approach enhances the accuracy of temperature measurements by increasing signal levels through higher incident light intensity while preventing non-linear optical effects, thereby improving the precision of temperature calculations.
Implementation Method 1
When light is transmitted in an optical fiber, the photons may be elastically scattered (Rayleigh scattering) and inelastically scattered (Raman scattering and Brillouin scattering). In Raman scattering, the scattered photon may have less energy than the incident photon (Stokes Raman scattering) due to absorption of energy by the fiber
Implementation Method 2
The implementation of fiber Bragg gratings (FBGs) in optical fibers to filter out Stokes Raman scattering
Implementation Method 3
A ratio of the anti-Stokes Raman scattering to the Stokes Raman scattering may be used to determine the temperature
Implementation Method 4
When light is transmitted in an optical fiber, the photons may be elastically scattered (Rayleigh scattering) and inelastically scattered (Raman scattering and Brillouin scattering)
Data Source
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AI summary
A distributed temperature sensor and a method of determining temperature are described. The distributed temperature sensor includes an optical fiber to filter or remove Stokes Raman scatter and prevent stimulated Raman scatter and a light source to inject light into the optical fiber. The distributed temperature sensor also includes a photodetector to detect light energy resulting from the light injected into the optical fiber, the light energy including anti-Stokes Raman scatter and Rayleigh scatter; and a processor to determine temperature based on a ratio of the anti-Stokes Raman scatter and the Rayleigh scatter.