Narrowband Optical Filter for LED Detection in Aircraft EVS

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Solution Overview

Problem

Conventional enhanced vision systems (EVS) struggle to detect LED-based airfield approach lighting systems effectively due to low thermal signature levels, which limits their reliability in low visibility conditions.

Innovation Solution

An enhanced vision system equipped with a sensor having a filter that filters out all but a specific narrowband spectrum of light to detect elements of a particular color, enhancing these elements for display, thereby improving detection and visibility in low visibility conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional enhanced vision systems use infrared sensors to detect thermal signatures, then they can operate in low visibility conditions, but they fail to reliably detect LED-based lighting systems due to low thermal signature levels

Engineering Contradiction:

Improvedetection reliabilityVSAvoidthermal signature detection capability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system changes the detection parameter from thermal infrared signatures to optical spectrum characteristics. By using a sensor with a narrowband optical filter instead of a broadband infrared sensor, the system detects LED lights based on their specific wavelength emissions rather than thermal radiation, resolving the inability to detect low-thermal-signature LED lighting

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the infrared detection mechanism with an optical detection mechanism. Instead of using thermal radiation detection, the system employs a visible or near-visible light sensor with spectral filtering to detect the optical emissions from LED approach lighting, fundamentally changing the detection physics

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the sensor uses a broadband filter to detect all light, then it captures more scene content, but it cannot selectively detect elements of a specific color like LED lights

Engineering Contradiction:

Improvecolor-specific detection capabilityVSAvoiddetected light content

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The system changes the spectral bandwidth parameter from broadband to narrowband filtering. The narrowband optical filter allows only a specific wavelength range corresponding to the LED light color to pass through, enabling selective detection of colored elements while blocking other wavelengths, thus achieving both specificity and sufficient signal detection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The filter is designed with localized spectral selectivity, targeting specific wavelength bands corresponding to different LED colors (red, green, blue). This allows the system to detect specific color elements in the scene while ignoring other wavelengths, achieving color-specific detection without requiring multiple sensors

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If the system enhances detection of specific color elements using narrowband filtering, then it improves visibility of LED lights, but it may reduce overall scene information available for detection

Engineering Contradiction:

Improvevisibility of detected elementsVSAvoidscene content information

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The system extracts only the relevant information (LED light elements of specific colors) from the complete scene using narrowband filtering. By isolating and enhancing only the critical approach lighting elements rather than processing all scene content, the system improves visibility of important features while the loss of unrelated scene information does not impact the primary function of detecting approach lighting

Inventive Principle:

Principle #2Taking out (Extraction)

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 enhances the detection and display of airfield approach lighting and other scene elements, improving aircraft operational safety even under adverse weather conditions by increasing the visibility of critical features like LED lights, trees, and other hazards.

Implementation Method 1

The enhanced vision system includes a sensor having a filter configured to filter out all but at least one narrowband spectrum of light from the scene to detect elements of a first color

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS9177204B1Spectrally enhanced vision system for low visibility operations

Publication Date: 2015.11.03 ROCKWELL COLLINS INC

AI summary

A system for enhancing an image displayed on a display unit of an aircraft is shown and described. The system includes an enhanced vision system that detects a scene and enhances the scene for display on the display unit. The enhanced vision system includes a sensor having a filter configured to filter out all but at least one narrowband spectrum of light from the scene to detect elements of a first color. The enhanced vision system causes remaining content of the scene to be removed from the filter output for completing the detection of the elements of the first color. The enhanced vision system enhances the elements of the first color on the display unit.