Optical Waveguide Sensor System for Anomaly Localization
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Solution Overview
Problem
Current methods for monitoring measurands and locating anomalies along waveguides, such as bleed air ducts in aerospace, are limited by the need for multiple, heavy, and prone-to-failure salt-filled sensors, which are costly and lack accurate localization, especially in extensive elongate regions.
Innovation Solution
A system using an optical waveguide with a light source emitting narrowband pulsed light and two sets of sensors, where the first set is grouped by equal sensor wavelengths and the second set is spaced farther apart, allowing for high-density, lightweight, and flexible anomaly detection without the need for each sensor to reflect at a unique wavelength, enabling precise localization of anomalies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If salt-filled sensors are used for temperature monitoring, then temperature detection capability is provided, but the system becomes heavy and complex requiring multiple connectors
Solution Approach 1:
The patent replaces the mechanical/electrical salt-filled conductor system with an optical fiber-based sensor system. Optical fibers are significantly lighter than metal conductors and connectors, eliminating the weight penalty associated with multiple connectors while maintaining temperature detection capability through optical measurement techniques.
Solution Approach 2:
The patent changes the measurement parameter from electrical characteristics (resistance, capacitance) to optical characteristics (light transmission, reflection, or scattering). This parameter change enables the use of lightweight optical fibers instead of heavy metal conductors, resolving the weight contradiction.
2Ease of manufacture
If salt-filled conductors are manufactured in short lengths, then manufacturing simplicity is maintained, but the number of connectors increases and installation time increases
Solution Approach 1:
The patent segments the monitoring system into distributed optical sensors along the waveguide rather than using discrete connectorable sections. This segmentation approach eliminates the need for multiple connectors and reduces installation time while maintaining manufacturing simplicity through standardized optical sensor production.
Solution Approach 2:
The patent merges multiple short sensor sections into a single continuous optical fiber monitoring system. This merging eliminates the need for connectors between sections, reducing both installation time and the number of potential failure points, while maintaining the simplicity of optical fiber manufacturing.
3Reliability
If electrical measurements are used for leak detection, then temperature monitoring is provided, but localization accuracy is insufficient
Solution Approach 1:
The patent replaces electrical measurements with optical measurements for temperature monitoring. Optical measurement techniques such as optical time-domain reflectometry (OTDR) and distributed Brillouin scattering provide superior localization accuracy by measuring the time of flight and position of optical signals, enabling precise identification of leak locations along the waveguide.
Solution Approach 2:
The patent introduces optical signals as an intermediary for temperature measurement instead of direct electrical contact. This intermediary approach enables non-contact temperature monitoring with higher spatial resolution and localization accuracy, as optical signals can be precisely positioned and their interaction with the medium (temperature changes) measured at specific locations along the waveguide.
4Reliability
If distributed temperature sensors are used, then continuous coverage is achieved, but the system becomes expensive and complex
Solution Approach 1:
The patent uses a single optical fiber that serves multiple functions: it acts as both the transmission medium for data communication and the sensing element for temperature distribution monitoring. This multi-functionality eliminates the need for separate electrical sensors and their associated connectors, reducing system complexity while maintaining continuous coverage along the waveguide.
Solution Approach 2:
The patent replaces complex electrical sensor systems with a simplified optical fiber-based system. Optical fibers inherently provide continuous distribution without the need for discrete connectors or complex wiring harnesses, reducing system complexity while achieving continuous temperature monitoring coverage along the entire waveguide length.
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
This approach allows for accurate, high-density monitoring of measurands along extensive waveguides, reducing weight and cost while improving localization accuracy, enabling early detection of leaks or anomalies in aerospace applications.
Implementation Method 1
an optical waveguide; a light source configured to selectively emit narrowband pulsed light of a given wavelength and duration through the optical waveguide
Implementation Method 2
each sensor of the first and second sets is configured to reflect a portion of light propagating along the waveguide at a respective sensor wavelength corresponding to a measurand
Data Source
AI summary
An apparatus for locating a measurand anomaly, such as a hot-spot, along an optical waveguide is provided comprising: an optical waveguide, a light source configured to transmit pulsed light along the waveguide, and a first and second set of sensors provided along the waveguide. Each sensor is configured to reflect a portion of light propagating along the waveguide at a respective sensor wavelength corresponding to a measurand. The first set of sensors provides one or more groups of sensors configured to detect a measurand anomaly within that group. The second set comprises a plurality of sensors each separated from the adjacent sensor of that set by a distance along the waveguide greater than half the distance travelled by the light along the waveguide during the pulse duration. A plurality of sensors of the first set is provided between each adjacent sensor of the second set. The apparatus further comprises a detector configured to monitor the light reflected by the sensors, and a control system configured to control the light source and the detector to both locate at least the group containing a measurand anomaly and to monitor the measurand using the second set.