Optical Window Temperature Sensing for Thermal Distortion Correction
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Solution Overview
Problem
Optical windows in airborne imaging systems face significant aerodynamic heating effects that introduce detrimental wavefront errors, with existing solutions either increasing emissions and noise or requiring additional infrared cameras, which impact system size, weight, and cost.
Innovation Solution
An optical window with integrated temperature sensing, featuring a thermally sensitive material between electromagnetic interference shielding layers, allowing for direct and local temperature measurements and dynamic thermal correction using the EMI wires as electrodes and resistive heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermal camera is placed behind the aperture to measure thermal gradients, then temperature distribution can be recorded, but system size, weight, and complexity increase
Solution Approach 1:
The patent combines the EMI shielding grid with temperature sensing functionality by integrating thermally sensitive material between the conductive structures. This merging eliminates the need for separate thermal cameras while providing both EMI protection and temperature measurement capabilities within a single integrated component.
Solution Approach 2:
The EMI shielding grid is given multiple functions: it continues to provide electromagnetic interference shielding while simultaneously serving as a temperature sensing platform. The conductive structures serve dual purposes as both shields and electrodes for the thermally sensitive material, reducing overall system complexity.
2Reliability
If uniform heating is applied to correct thermal gradients, then wavefront errors can be corrected, but emissions and noise increase
Solution Approach 1:
The patent applies local quality by enabling spatially selective heating through the EMI grid. Individual regions of the window can be heated independently based on measured temperature distribution, allowing precise correction of thermal gradients only where needed rather than uniform heating of the entire aperture.
Solution Approach 2:
The system implements feedback control by continuously measuring temperature distribution through the integrated thermally sensitive material and using this information to adjust the heating pattern. The controller modifies the voltage applied to different regions of the EMI grid based on real-time temperature measurements, creating a closed-loop system that optimizes heating efficiency and minimizes unnecessary emissions.
3Measurement precision
If additional temperature sensing components are added to the optical window, then temperature measurement capability improves, but system weight and power consumption increase
Solution Approach 1:
The temperature sensing functionality is merged into the existing EMI shielding structure. The thermally sensitive material is integrated between the conductive layers of the shield, eliminating the need for separate sensing components and reducing overall weight while maintaining measurement capability.
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 optical distortions with minimal impact on system size, weight, and power consumption, improving optical window performance during hypersonic flight.
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
Implementation Method 2
the controller is configured to selectively bias one or more wires of the first plurality of electrically conductive wires and one or more wires of the second plurality of electrically conductive wires to resistively heat the selected wires
Implementation Method 3
Optical domes and windows are used in a variety of systems and applications where an optically transparent window is needed, for example, in airborne imaging systems to protect underlying imaging optics from the environment. These domes or windows can be subjected to significant aerodynamic heating effects
Data Source
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.