Fiber-Optic Sensor Liquid Immersion Detection via Reflection Switching
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Solution Overview
Problem
Existing fiber-optic sensors for detecting water immersion in optical fiber networks are prone to external environmental influences, such as dust, and are not suitable for multiple location detection due to high bending loss and vulnerability to breakdown.
Innovation Solution
A fiber-optic sensor system with an optical fiber and an interface material layer having an angled physical contact surface, which changes from a rough diffusion reflection in a dry state to a smooth specular reflection when wet, allowing for real-time detection using an optical time domain reflectometer and a branching design to prevent breakdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-woven cloth is used to absorb water for detection, then water immersion can be detected through swelling and bending loss, but the bending loss becomes as high as 10 dB making multi-location detection impossible and the detection wiring becomes vulnerable to breakdown
Solution Approach 1:
The patent replaces the mechanical bending mechanism with an optical reflection mechanism. Instead of using non-woven cloth that swells and bends the fiber (mechanical system), the invention uses an interface material layer whose surface roughness changes with moisture absorption, altering the optical reflection characteristics (optical system). This substitution eliminates the high bending loss and mechanical stress on detection wiring while maintaining water immersion detection capability.
Solution Approach 2:
The patent changes the optical reflection parameter from the mechanical bending loss mechanism to the surface roughness reflection mechanism. The interface material layer transitions from a rough surface (diffuse reflection) in dry state to a smooth surface (specular reflection) in wet state, changing the optical parameter that is detected by the OTDR. This parameter change enables detection without the harmful mechanical effects of the previous approach.
2Measurement precision
If a single-location liquid level sensor is used, then water immersion at that specific location can be detected, but the sensor surface is easily affected by external environmental factors such as dust influencing its function
Solution Approach 1:
The patent divides the detection system into multiple independent detection points along the optical fiber network. Each detection point has its own interface material layer that can independently detect water immersion. This segmentation allows multiple locations to be monitored simultaneously and reduces the impact of environmental factors on any single sensor, as each detection point operates independently.
3Adaptability or versatility
If multiple detection points are implemented using traditional sensors, then water immersion at multiple locations can be detected, but the system complexity increases and maintenance becomes difficult due to vulnerability to breakdown
Solution Approach 1:
The patent creates a universal detection mechanism where the same interface material layer principle is applied at multiple detection points along the optical fiber. Each detection point uses the same simple structure of optical fiber with interface material layer, making the system scalable and easy to maintain. The uniformity of the detection mechanism across multiple locations simplifies the overall system compared to using different sensor types.
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 simultaneous detection of liquid immersion at multiple locations without affecting other detection points, with a simple and cost-effective design that allows easy maintenance and replacement, achieving a significant optical power difference of over 3 dB between dry and wet states.
Implementation Method 1
The interface material layer has a rough surface to produce a diffusion reflection when in a dry state
Implementation Method 2
The interface material layer has a smooth surface to produce a specular reflection when absorbed a liquid in a wet state
Implementation Method 3
observe with an optical time domain reflectometer (OTDR)
Data Source
AI summary
A fiber-optic sensor for liquid-immersion detection includes an optical fiber and an interface material layer. The optical fiber has an angled physical contact (APC) surface. The interface material layer contacts with the APC surface. The interface material layer has a rough surface when in a dry state to produce a diffusion reflection. The interface material layer has a smooth surface to produce a specular reflection when the interface material layer absorbs a liquid in a wet state.