Multimode Fiber Interrogator for Aerospace Sensing

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Solution Overview

Problem

Current optical sensing systems for aerospace applications are costly and complex due to their reliance on sensitive laser-based technologies, which are prone to failure in harsh environments, and traditional methods like Fiber Bragg Grating sensors are complicated to manufacture and sensitive to temperature changes.

Innovation Solution

The use of a broad spectrum light source with a multimode optical fiber coupled to photonic crystal sensors, which support multiple propagation modes and are less complex to manufacture, providing a robust and lightweight solution for sensing parameters like pressure and temperature by reflecting light across different wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If laser-based sensing systems are used, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvesensing precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex laser-based optical sensing systems with a simpler LED-based system. Specifically, it substitutes VCSELs (vertical-cavity surface-emitting lasers) with LEDs, and replaces single-mode fiber with multimode fiber, thereby reducing system complexity while maintaining sensing functionality through photonic crystal sensor technology

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes key system parameters: switching from narrow-spectrum laser light to broad-spectrum LED light, changing from single-mode to multimode fiber, and operating at different wavelength ranges. These parameter changes enable the use of simpler, more robust components while achieving comparable measurement precision through the photonic crystal sensor's wavelength-dependent response

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If single mode fiber is used with lasers, then measurement precision is improved, but reliability in harsh environments deteriorates

Engineering Contradiction:
Improvesensing precisionVSAvoidenvironmental reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent adopts components that are more robust and better suited for harsh environments, even if they have different performance characteristics. LEDs and multimode fiber are chosen over lasers and single-mode fiber because they are more resistant to environmental stressors like temperature variations and physical damage, improving reliability in aerospace applications

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent employs photonic crystal sensors that can be integrated with the structural components being monitored, creating a composite sensing system. These sensors can be embedded within aerospace structures, allowing direct measurement of structural parameters while improving both reliability and integration

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If traditional sensor methods are used, then manufacturing capability is improved, but device complexity increases

Engineering Contradiction:
Improvemanufacturing capabilityVSAvoidsystem complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent describes a sensor system where photonic crystal sensors can monitor multiple parameters (temperature, strain, pressure) simultaneously through a single integrated sensor element. The system can also monitor multiple sensors through a single multimode fiber, reducing overall system complexity while maintaining ease of manufacture

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces traditional mechanical sensing elements (such as FBG sensors requiring complex writing processes) with photonic crystal sensors that can be manufactured using standard semiconductor fabrication techniques, thereby improving ease of manufacture while reducing system complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 reduces the weight and complexity of the interrogator system, enabling miniaturization and improved reliability in harsh environments while simplifying the manufacturing process and reducing sensitivity to temperature changes.

Implementation Method 1

a broad spectrum light source capable of emitting light having a spectral width spanning at least approximately 20 nm, and at least one optical sensor coupled to the broad spectrum light source by at least one multimode optical fiber, wherein the at least one multimode optical fiber is configured to support a plurality of propagation modes

Methodology Applied
Scientific EffectLight propagation in multimode fiber: Optical Fibre

Implementation Method 2

at least one optical sensor coupled to the broad spectrum light source by at least one multimode optical fiber... reflecting light across different wavelengths

Methodology Applied
Scientific EffectPhotonic crystal light reflection: Photonic Crystal

Implementation Method 3

a broad spectrum light source capable of emitting light having a spectral width spanning at least approximately 20 nm

Methodology Applied
Scientific EffectBroad spectrum light emission: Light Emitting Diode

Data Source

PatentEP2800949B1Multimode fiber interrogator
Publication Date: 2019.03.13 THE BOEING CO
  • EP2800949B1 patent drawingFigure 1~2
  • EP2800949B1 patent drawingFigure 3~4
  • EP2800949B1 patent drawingFigure 5

AI summary

An optical interrogator system including a broad spectrum light source capable of emitting light having a spectral width spanning at least approximately 20 nm, and at least one optical sensor coupled to the broad spectrum light source by at least one multimode optical fiber, wherein the at least one multimode optical fiber is configured to support a plurality of propagation modes, and a method of using the same are disclosed herein.