Fiber Optic Smoke Detection Using Multi-Angle Light Scattering
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Solution Overview
Problem
Conventional smoke detection systems face challenges in discriminating between hazardous smoke and non-hazardous particulates, leading to false alarms, and require improved sensitivity to detect smaller fires in critical aircraft locations while minimizing false alarms.
Innovation Solution
A fiber optic detection system utilizing a network of nodes with a light source and light sensitive devices, including photodiodes, to analyze light scattering from multiple angles, converting scattered light into signals for a control unit to determine the presence and magnitude of smoke or other conditions, and employing a light mold to maintain orientation and collect scattered light from various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photoelectric smoke detection systems are used to detect smoke particles, then the system can detect the presence of smoke, but the system generates false alarms from non-hazardous particulates
Solution Approach 1:
The detection system is segmented into multiple independent detection channels, each with its own light source and photodetector positioned at different angles. This segmentation allows the system to analyze light scattering from multiple perspectives simultaneously, enabling discrimination between smoke particles and non-hazardous particulates based on their different scattering patterns at various angles.
Solution Approach 2:
The system transitions from single-angle detection to multi-angle detection by positioning photodetectors at different angular positions relative to the light sources. This dimensional expansion in the angular domain provides additional information about particle characteristics, enabling the system to distinguish between hazardous smoke and non-hazardous particulates that would appear identical in a single-angle detection system.
2Measurement precision
If the sensitivity of the fire detection system is increased to detect smaller fires, then early detection capability is improved, but the risk of false alarms increases
Solution Approach 1:
The system incorporates feedback mechanisms where the signals from multiple photodetectors are processed together to evaluate scattering patterns. The control system analyzes the combined information from all detection channels, comparing the observed scattering patterns against expected patterns for both smoke and non-hazardous particulates. This feedback-based pattern recognition allows the system to maintain high sensitivity for early smoke detection while using the multi-angle scattering information to filter out false alarms from non-hazardous sources.
3Measurement precision
If anisotropic light scattering is used to reduce false alarms, then discrimination capability is improved, but the device complexity increases due to multiple angles and detectors required
Solution Approach 1:
The system merges multiple detection functions into a single integrated apparatus. Multiple light sources and photodetectors are positioned in fixed geometric relationships, and the control system processes all signals simultaneously through a unified algorithm. This merging approach achieves the complexity reduction goal by consolidating what would otherwise be separate detection systems into one coordinated unit, making the multi-angle anisotropic scattering measurement practical for real-world deployment.
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 system effectively reduces false alarms by accurately discriminating between smoke and non-hazardous sources, enabling early detection of smaller fires and localizing their location within aircraft compartments, thus enhancing fire control and safety.
Implementation Method 1
a first fiber optic core of a fiber optic cable to transmit light from a light source to the node and a second fiber optic core of the fiber optic cable to convey scattered light back to the light sensitive device
Implementation Method 2
Light is transmitted from 4 to 7 through a single core fiber optic cable 1. The fiber optic cable defines a plurality of nodes 3, each node comprising a reflector (indicated as 3). If smoke is present at one of the nodes, light is scattered at various angles
Implementation Method 3
the light sensitive device converts the scattered light associated with the node into a signal receivable by the control unit
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A detection system for measuring one or more conditions within a predetermined area includes a fiber harness (30) having at least one fiber optic cable for transmitting light. The at least one fiber optic cable defines a node (34) arranged to measure the condition. The node is arranged such that light scattered by an atmosphere adjacent the node is received by at least one core of the fiber optic cable at least one scattering angle relative to light transmitted through the node. A control system (50) is operably coupled to the fiber harness such that scattered light associated with the node is transmitted to the control system. The control system analyzes the scattered light to determine at least one of a presence and magnitude of the one or more conditions at the node.