Optical Window EMI Grid for Temperature Sensing and Thermal Correction

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Solution Overview

Problem

Optical windows in airborne imaging systems face significant aerodynamic heating, leading to detrimental wavefront errors due to unmeasured and uncorrected temperature distributions across the aperture, with existing solutions increasing emissions and noise or requiring additional infrared cameras, which impact system size, weight, and cost.

Innovation Solution

An optical window with a thermally sensitive material integrated between electromagnetic interference shielding layers, allowing for direct and local temperature measurements and dynamic thermal correction, using the shielding grid's conductive wires for both sensing and resistive heating to adjust temperature profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a thermal camera is placed behind the aperture to measure temperature distribution, then temperature measurement capability is improved, but system size, weight, and cost increase

Engineering Contradiction:
Improvetemperature measurement capabilityVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of stationary object

Solution Approach 1:

The patent combines the temperature sensing function with the existing electromagnetic interference shielding grid structure. The thermally sensitive material is integrated between the conductive structures of the shield, allowing the shielding component to serve dual purposes: electromagnetic shielding and temperature sensing, thereby eliminating the need for a separate thermal camera and reducing system weight

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electromagnetic interference shielding grid is designed to perform multiple functions simultaneously: it provides electromagnetic shielding and serves as a temperature sensing platform. The conductive structures of the shield act as both EMI barriers and sensing elements that detect temperature through the thermally sensitive material, achieving multi-functionality without additional components

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

2Reliability

If resistive heating wires are embedded to correct thermal gradients, then thermal correction capability is improved, but emissions and noise increase

Engineering Contradiction:
Improvethermal correction capabilityVSAvoidemissions and noise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system implements a feedback mechanism where the thermally sensitive material continuously monitors the temperature distribution across the aperture, and this temperature information is used to control the resistive heating elements. The heating wires are selectively activated based on measured temperature gradients, creating a closed-loop system that corrects thermal distortions only where and when needed, minimizing unnecessary heating emissions and noise

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Instead of uniformly heating the entire aperture, the patent applies resistive heating locally to specific regions where thermal gradients are detected. The conductive structures of the shielding grid allow selective activation of heating elements in different zones, providing localized thermal correction that reduces overall energy consumption and minimizes harmful emissions and noise compared to uniform heating approaches

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If conventional EMI shielding is used without temperature sensing, then electromagnetic shielding is provided, but temperature distribution remains unmeasured and uncorrected

Engineering Contradiction:
Improveelectromagnetic shieldingVSAvoidtemperature distribution information
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent merges the electromagnetic shielding function with temperature sensing capability by integrating a thermally sensitive material between the conductive structures of the EMI shield. This combination allows the same structural component to provide both electromagnetic protection and temperature measurement, eliminating the need for separate sensing systems and enabling simultaneous acquisition of both functions

Inventive Principle:
Principle #5Merging (Combining)

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

Enables real-time, high-spatial resolution temperature measurements and correction of thermally-induced aberrations with minimal impact on system size, weight, and power, improving optical performance during aerodynamic heating events.

Implementation Method 1

a thermally sensitive material disposed between the first and second electrically conductive structures, the thermally sensitive material having an electrical property that varies as a function of temperature

Methodology Applied
Scientific EffectThermal sensitivity: Thermo-resistive Effect

Implementation Method 2

heating the aperture by resistively heating embedded wires

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Data Source

PatentEP4010774B1Optical window with integrated temperature sensing
Publication Date: 2024.02.14 RAYTHEON CO
  • EP4010774B1 patent drawingFigure 1A~1B
  • EP4010774B1 patent drawingFigure 2A~2C
  • EP4010774B1 patent drawingFigure 3

AI summary

Methods and apparatus for measuring and optionally adjusting the temperature profile of an optical window. In one example, an optical window with integrated temperature sensing functionality includes a first window layer of an optically transparent material, a second window layer of the optically transparent material, an electromagnetic interference shielding grid disposed between the first and second window layers and including a first electrically conductive structure and a second electrically conductive structure, and a thermally sensitive material disposed between the first and second electrically conductive structures, the thermally sensitive material having an electrical property that varies as a function of temperature.