Fiber-Optic Temperature Profiling with Feedback Control
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Solution Overview
Problem
Existing distributed temperature sensing (DTS) systems face challenges in providing high accuracy temperature measurements in long length areas due to variations in attenuation profiles, which are not always smooth exponential, and existing solutions either increase complexity and cost or fail to account for environmental changes.
Innovation Solution
A high precision fiber-optic device and method using a source of pulsed optical radiation, optical amplifying means with controllable power output, a bidirectional optical filter, and a reference optical fiber to maintain a fixed intensity level of anti-Stokes Raman components, ensuring accurate temperature profiling by controlling the power output based on feedback from the reference optical fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two additional optical radiation sources are used to generate Rayleigh backscattered components for attenuation profile correction, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and utilizes the Rayleigh backscattered components that are naturally generated by the primary optical source in the Stokes and Anti-Stokes frequencies, rather than requiring two additional optical radiation sources. This selective extraction of useful signal components reduces device complexity while maintaining the ability to correct attenuation profiles for accurate temperature measurements.
2Measurement precision
If a reference optical fiber with predetermined optical properties is used for self-calibrating, then measurement precision is improved, but additional attenuation alteration due to environmental changes is not compensated
Solution Approach 1:
The patent implements a feedback mechanism where the Rayleigh backscattered components from the reference optical fiber are continuously monitored and used to dynamically correct the attenuation profile. This feedback loop enables the system to adapt to environmental changes and attenuation variations in real-time, maintaining measurement precision without requiring the reference fiber to be completely isolated from environmental influences.
3Device complexity
If the attenuation profile adjustment is based on smooth exponential assumption, then device complexity is reduced, but measurement precision deteriorates when the assumption does not match reality
Solution Approach 1:
The patent changes the approach from assuming a fixed smooth exponential attenuation profile to dynamically determining the attenuation profile parameters based on actual Rayleigh backscattered signal measurements. By allowing the attenuation parameters to vary and be corrected based on real signal characteristics, the system achieves high measurement precision without requiring complex a priori assumptions about the attenuation profile shape.
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 provides a cost-effective and convenient method for high precision temperature profiling in long length areas, maintaining accuracy despite environmental changes and variations in attenuation profiles.
Implementation Method 1
optical amplifying means with a controllable power output
Implementation Method 2
Stokes and anti-Stokes Raman components of optical radiation back scattered along the reference optical fiber and back scattered along the sensing optical fiber
Data Source
AI summary
A high precision fiber-optic device and method are developed for measuring a temperature profile in a long length area. The temperature profile is derived based on a ratio between the intensities of anti-Stokes Raman and Stokes Raman backscattered components. The power output of the amplified pulsed optical radiation delivered to the sensing optical fiber via a reference optical fiber, is controlled such as to maintain a substantially fixed intensity level of the anti-Stokes Raman component of the optical radiation back scattered from the reference optical fiber. Controlling the output power of the of the amplified pulsed optical radiation is carried out based on a feedback representative of the intensity level of the anti-Stokes Raman component of the optical radiation back scattered from the reference optical fiber.