Twin Hole Optical Fiber Temperature Sensor with Vernier Effect
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fiber optic temperature sensors lack sufficient sensitivity due to limitations in their design, particularly in the Michelson interferometer configuration.
Innovation Solution
A temperature sensor utilizing a twin hole optical fiber with a thermal-sensitive structure and a gradient refractive index optical fiber, forming two Michelson interferometers in a parallel-connection structure to enhance sensitivity through a vernier effect by controlling the length of the thermal-sensitive material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional fiber optic Michelson interferometer is used for temperature sensing, then the sensor achieves basic temperature measurement capability with simple fabrication and good stability, but the temperature sensitivity is insufficient
Solution Approach 1:
The single-hole fiber structure is segmented into a twin-hole structure with two separate holes. The first hole contains a thermal-sensitive structure while the second hole remains empty or contains different material. This segmentation creates two distinct optical paths with different thermal responses, enabling differential measurement that significantly enhances temperature sensitivity while maintaining manageable structural complexity
Solution Approach 2:
The thermal-sensitive structure is selectively placed only in the first hole of the twin-hole fiber, creating local quality differentiation. This allows one optical path to be highly sensitive to temperature changes while the other serves as a reference or has different sensitivity characteristics, thereby improving overall temperature measurement precision without requiring the entire fiber structure to be complex
2Measurement precision
If the thermal-sensitive structure length is increased to improve sensitivity, then temperature measurement precision improves, but the optical path length difference becomes too large causing loss of interference fringes
Solution Approach 1:
The patent optimizes the length parameter of the thermal-sensitive structure to a specific range that balances two competing requirements: it is long enough to provide sufficient temperature sensitivity but short enough to maintain acceptable optical path length difference for interference fringe visibility. This parameter optimization resolves the contradiction between precision and reliability
Solution Approach 2:
The twin-hole fiber creates an asymmetric structure where one hole contains a thermal-sensitive structure and the other does not, or contains different material properties. This asymmetry generates different optical path lengths that are carefully controlled to produce visible interference fringes while maintaining high temperature sensitivity through the differential measurement principle
Data Source
AI summary
A fiber optic sensing head includes a single-mode optical fiber, a twin hole optical fiber including a cladding region and a core region surrounded by the cladding region, and the core region includes a second core located at an axis center, as well as a first and second round holes symmetrically distributed with respect to the second core; an incoming end of a gradient refractive-index fiber is connected to an outgoing end of the twin hole optical fiber with the incoming end of the gradient index fiber aligned with the outgoing end of the single-mode optical fiber at center. A thermal-sensitive structure is filled in a preset length part of the second round hole extending along an axial direction of the twin hole optical fiber. An incoming end of the twin hole optical fiber is connected to an outgoing end of the gradient index optical fiber with displacement.