Photonic Band Gap Array Infrared Imaging Without Cryogenic Cooling

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Solution Overview

Problem

High-quality infrared imaging systems require expensive active cryogenic cooling, making them larger, heavier, and more complex, while uncooled systems using microbolometers or interferometers are costly and have limited thermoelectric sensitivity.

Innovation Solution

An imaging system employing an array of photonic band gap material cells that shifts the absorption edge frequency in response to infrared radiation, increasing temperature and enhancing sensitivity and dynamic range by detecting visible or near-infrared radiation transmitted through the cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If active cryogenic cooling is used in infrared imaging systems, then image quality is improved, but system complexity, weight, and cost increase

Engineering Contradiction:

Improveimage qualityVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the cooling system from the infrared imaging system by using photonic band gap materials that inherently provide thermal isolation to the focal plane array, eliminating the need for active cryogenic cooling while maintaining image quality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces photonic band gap materials as an intermediary between the environment and the focal plane array, which mediate thermal energy transfer by blocking infrared radiation while allowing visible light transmission, thus passively cooling the detector

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If uncooled infrared imaging systems using microbolometers or interferometers are used, then system complexity is reduced, but sensitivity is limited

Engineering Contradiction:

Improvesystem complexityVSAvoidsensitivity

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the operating parameters by using photonic band gap materials with specific absorption edges matched to the infrared source wavelength, enabling the focal plane array to detect transmitted radiation with higher sensitivity than conventional uncooled systems

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite photonic band gap structures combining materials with different thermal and optical properties to achieve both thermal isolation and enhanced infrared absorption, improving sensitivity while maintaining system simplicity

Inventive Principle:

Principle #40Composite materials

3Measurement precision

If photonic band gap material cells are used to detect transmitted radiation, then sensitivity and dynamic range are improved, but manufacturing difficulty increases

Engineering Contradiction:

ImprovesensitivityVSAvoidmanufacturing difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent segments the photonic band gap structure into repetitive unit cells with specific geometric patterns, which can be manufactured using standard semiconductor fabrication techniques, thereby reducing manufacturing difficulty while achieving the desired sensitivity enhancement

Inventive Principle:

Principle #1Segmentation

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 achieves improved sensitivity and dynamic range over prior uncooled infrared imaging systems without the need for cryogenic cooling, resulting in a more compact, lightweight, and cost-effective solution.

Implementation Method 1

Infrared images from a field of view directed onto the photonic band gap material cells increase the temperature of the illuminated cells, shifting the absorption edge frequency for those cells

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

increase the temperature of the illuminated cells, shifting the absorption edge frequency

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

A focal plane array detects the visible or near-infrared radiation from the narrow band source that has been transmitted through the photonic band gap material cells

Methodology Applied

Scientific EffectTransmission:

Data Source

PatentUS8569696B2Imaging system and method using a photonic band gap array

Publication Date: 2013.10.29 RAYTHEON CO

AI summary

An imaging system (20) includes an array (24) of photonic band gap material cells. The band gap material has an absorption edge at about the emission frequency of a source (22) of electromagnetic energy. Images from a field of view (26) directed onto the photonic band gap array (24) increase the temperature of the illuminated cells, shifting the absorption edge frequency for those cells. A focal plane array (28) detects the electromagnetic radiation transmitted through the photonic band gap array (24) from the source (22). The intensity of the transmitted radiation is proportional to the shift in the photonic band gap edge.