Polarization Maintaining Fiber Temperature Sensor with 45-Degree Splice

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Solution Overview

Problem

Existing optical fiber temperature sensors are complex to manufacture, costly, and require spectral analysis, making them unsuitable for high voltage environments with high precision and low cost requirements.

Innovation Solution

An optical fiber temperature sensor utilizing polarization maintaining fibers with a 45-degree fusion splicing angle between the transmission and sensing fibers, along with an optical transceiver module, simplifies the structure and allows adjustable sensitivity by varying the length of the sensing element, enabling accurate temperature measurement under high voltage conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If spectral analysis methods (fiber grating, Fabry-Perot etalon, semiconductor absorption sensor) are used for optical fiber temperature sensing, then measurement accuracy is improved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the temperature sensing function from complex spectral analysis systems and implements it using a simple polarization-maintaining fiber with a 45-degree fusion spliced connector. This eliminates the need for fiber gratings, Fabry-Perot etalons, or semiconductor absorption sensors, dramatically simplifying the device structure while maintaining temperature measurement capability through polarization state changes.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces complex optical spectral analysis systems with a polarization-based optical system. Instead of using spectral filters, gratings, or absorption sensors, the invention uses polarization-maintaining fibers and polarization state detection to measure temperature, substituting a simpler optical mechanism for the complex mechanical and spectral analysis systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If spectral analysis methods are used for optical fiber temperature sensing, then measurement accuracy is improved, but manufacturing cost increases

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses inexpensive polarization-maintaining fibers and standard fusion splicing techniques instead of expensive fiber gratings, Fabry-Perot etalons, or semiconductor absorption sensors. The 45-degree fusion spliced connector is a simple, low-cost component that can be manufactured using standard fiber splicing equipment, dramatically reducing manufacturing costs while maintaining measurement accuracy.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If polarization maintaining fibers with 45-degree fusion splicing are used, then device complexity is reduced, but temperature measurement accuracy must be maintained

Engineering Contradiction:

Improvesensor structure complexityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the polarization state parameters by using a 45-degree fusion spliced connector between polarization-maintaining fibers. This specific angular parameter creates a known transformation of polarization states that varies with temperature, allowing accurate temperature measurement through polarization analysis while keeping the device structure simple.

Inventive Principle:

Principle #35Parameter changes

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 solution provides a simple, cost-effective, and highly accurate temperature measurement with adjustable sensitivity, achieving an accuracy of 0.5% and compatibility with high voltage conditions.

Implementation Method 1

a temperature sensing element comprising a second polarization maintaining fiber

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

the first polarization maintaining fiber of the transmission fiber is fusion spliced with the second polarization maintaining fiber of the temperature sensing element

Methodology Applied

Scientific EffectFusion splicing: Welding

Implementation Method 3

a fiber reflector provided at the other end of the temperature sensing element

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8449178B2Optical fiber temperature sensor

Publication Date: 2013.05.28 BEIJING QI RED PHOTOELECTRICAL TECH CO LTD

AI summary

An optical fiber temperature sensor includes an optical transceiver module, a transmission fiber and a sensing head. When the transmission fiber is a polarization maintaining fiber, the sensing head includes a temperature sensing element and a fiber reflector, the temperature sensing element is a section of polarization maintaining fiber. The transmission fiber is fusion spliced with the temperature sensing element, an angle between a polarization axis of the transmission fiber and that of the temperature sensing element is 45 degree at the fusion splicing point. When the transmission fiber is a single-mode fiber, the sensing head includes a polarizer. An angle between a polarization axis of the polarization maintaining fiber connecting the temperature sensing element with the polarizer and that of the polarization maintaining fiber of the temperature sensing element is 45 degree at the fusion splicing point. The present invention is of simple principle and structure, and facilitates manufacturing.