Fiber-Optic Sensor Calibration Using Phase Transition Fixed Points
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Solution Overview
Problem
Fiber-optic temperature sensors used in civil engineering structures face challenges with temperature drift over time, requiring regular calibration, and existing calibration methods are either unreliable or limited to relative measurements, lacking durability and reproducibility for long-term use.
Innovation Solution
A device with a heat transfer mechanism and thermally connected fixed points made of materials that change state at predefined temperatures, allowing for absolute temperature calibration of fiber-optic sensors, ensuring stability and accuracy over extended periods by using a device body with a passage for the optical fiber and heat conducting materials for efficient heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If fiber-optic temperature sensors are used for long-term monitoring in civil engineering structures, then the measurement duration can extend beyond ten years, but temperature drift occurs over time requiring regular calibration
Solution Approach 1:
The patent uses phase transition materials (such as gallium melting at 29.76°C or indium melting at 156.6°C) as fixed points for temperature calibration. These materials undergo phase transitions at well-defined temperatures, providing stable reference points for calibrating fiber-optic sensors. The phase transition creates a reproducible thermal state that allows the sensor to be calibrated against a known temperature, thereby maintaining measurement reliability over the sensor's operational lifetime.
2Measurement precision
If existing calibration methods are used, then calibration can be performed, but the measurements are relative and lack absolute temperature reference
Solution Approach 1:
The calibration device is self-calibrating through the use of phase transition materials with well-defined melting points. The system uses the phase transition itself as the reference standard, eliminating the need for external calibration equipment. The fiber-optic sensor measures the temperature at the phase transition point, and since the phase transition temperature is a fundamental physical property, the calibration is both absolute and reproducible.
3Measurement precision
If secondary temperature sensors are used for calibration, then absolute temperature measurement is possible, but the sensors themselves exhibit thermal drift and have limited reproducibility
Solution Approach 1:
The patent replaces secondary temperature sensors with phase transition materials as the calibration reference. Phase transitions occur at well-defined temperatures determined by fundamental thermodynamic properties, not by sensor characteristics. This eliminates the thermal drift problem inherent in secondary sensors, as the phase transition temperature remains constant regardless of sensor aging or environmental conditions.
4Temperature
If heat exchange systems are used to regulate temperature during calibration, then temperature control is achieved, but the system complexity increases
Solution Approach 1:
The phase transition material automatically maintains a constant temperature during the phase change process, eliminating the need for complex active temperature control systems. The material absorbs or releases latent heat during phase transition, naturally stabilizing the temperature at the transition point. This self-regulating property simplifies the calibration device structure while maintaining precise temperature control.
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 durable and reproducible absolute temperature calibration of fiber-optic sensors, reducing the risk of drift over time, even beyond ten years, with precise temperature control and accurate measurements through the use of materials with defined change-of-state temperatures.
Implementation Method 1
a first fixed point made from a first material having at least one first predefined temperature at which the state thereof changes
Data Source
AI summary
The invention relates to a device (100) for calibrating the temperature of a fiber-optic temperature sensor, with which an optical fiber (10) of a fiber-optic temperature sensor is to be provided. The device (100) comprises a device body (101) having a passage (109) through which the optical fiber (10) is to pass, and a means for transferring heat energy. The device (100) further comprises at least one portion (160a), referred to as a first fixed point, which is made from a first material having at least a first predefined temperature at which the state thereof changes. The first fixed point (160a) is thermally connected to the optical fiber (10) when the optical fiber (10) is provided with the device (100). The heat-transferring means is arranged in the device body (101) such that, during the actuation thereof, the heat-transferring means exchanges heat energy with the first fixed point (160a) so as to cause a change in the state thereof at the first predefined temperature.