Multi-Wavelength Sagnac Sensor Array for Intrusion Localization
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Solution Overview
Problem
Current perimeter defense systems using optical fibers are limited in providing accurate feedback on intrusions, failing to identify and track objects effectively, and are prone to false alarms due to poor discrimination between environmental conditions.
Innovation Solution
A perimeter defense system utilizing an intensity modulated broadband optical signal source and a multi-wavelength Sagnac sensor array with optical couplers, sensors, and detectors to generate and analyze interference signals across multiple wavelength bands, allowing for precise identification and tracking of intrusions while mitigating environmental interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-wavelength optical fiber sensor is used, then the device complexity is low, but the measurement precision and ability to distinguish environmental conditions from intrusions is poor
Solution Approach 1:
The optical signal is segmented into multiple wavelength bands using a demultiplexer, with each wavelength band processed by dedicated sensors and detectors. This segmentation allows precise measurement of different optical path length changes caused by intrusions versus environmental conditions, significantly improving intrusion localization accuracy while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The system transitions from single-wavelength detection to multi-wavelength detection, adding the wavelength dimension to the measurement space. By measuring optical path length changes across multiple wavelength bands simultaneously, the system can distinguish between intrusions and environmental conditions with high precision, effectively utilizing spectral information as an additional measurement dimension
2Reliability
If environmental conditions are not distinguished, then the device complexity is low, but false alarms increase due to poor discrimination
Solution Approach 1:
The system uses feedback from multiple wavelength band measurements to distinguish environmental conditions from intrusions. By comparing the pattern of optical path length changes across different wavelength bands, the signal processing system can identify characteristic signatures of intrusions versus environmental disturbances, significantly reducing false alarms while maintaining reliable detection
Solution Approach 2:
The system changes the measurement parameter from single-wavelength intensity detection to multi-wavelength optical path length measurement. This parameter change enables the system to detect subtle differences in how environmental conditions and intrusions affect light propagation across different wavelengths, improving reliability by providing discriminative information for accurate event classification
3Loss of information
If intrusion tracking and identification is not implemented, then the device complexity is low, but the loss of information about intrusion characteristics is high
Solution Approach 1:
The system uses optical path length change measurements as an intermediary to infer intrusion characteristics. By measuring how intrusions affect light propagation through the optical fiber, the system can identify and track intrusion events without requiring direct physical contact or complex imaging systems, minimizing information loss while keeping the identification system relatively simple
Solution Approach 2:
The system replaces mechanical or electronic tracking systems with optical measurement-based identification. By using multi-wavelength optical signals to detect and characterize intrusions through optical path length changes, the system achieves comprehensive intrusion information capture without the complexity of mechanical scanning or electronic tracking mechanisms
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 provides accurate and reliable detection and tracking of intrusions, reducing false alarms by distinguishing between environmental conditions and enhancing the precision of intrusion localization.
Implementation Method 1
the clockwise and counter clockwise waves for each of the separate optical signals propagate through the plurality of sensors and then combine in the optical coupler to form a plurality of interference signals
Implementation Method 2
a first optical fiber having a first portion is connected to the optical coupler and arranged to guide a clockwise wave for each of the separate optical signals along a corresponding optical path. The first optical fiber has a second portion connected to the optical coupler and arranged to guide a counter clockwise wave
Data Source
AI summary
An intensity modulated broadband optical signal source is arranged to produce optical signals in a plurality of wavelength bands. A demultiplexer/multiplexer pair receives optical signals from the optical signal source and produces a separate optical signal for each wavelength band. An optical coupler is arranged to receive the separate optical signals. Optical fiber loops connected to the optical coupler guides both clockwise and counter clockwise waves for each of the separate optical signals. The optical signals propagate through a sensor in each loop and then combine in the optical coupler to form a plurality of interference signals in each wavelength band. A multiplexer is optically coupled to the optical coupler to receive the interference signals therefrom, and a detector array having a selected detector corresponding to the each of the plurality of wavelength bands is arranged to provide an electrical signal that indicates the interference signals for each wavelength band.