Real-Time Optical Window Thermal Gradient Correction
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Solution Overview
Problem
Conventional methods for determining thermal gradients in airborne optical windows, such as lookup tables and thermocouples, fail to provide precise real-time measurements, leading to reduced sensor performance due to thermal distortions, especially in complex and conformal geometries.
Innovation Solution
A thermal imager is used to image the optical window and generate a thermal gradient map, which is then processed to apply corrections to active optical elements via an optical corrector, enabling real-time accommodation for thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lookup tables are used to estimate index of refraction change, then the system can operate without additional sensors, but the thermal gradient cannot be precisely determined in real-time
Solution Approach 1:
A thermal imager is introduced as an intermediary device to directly measure the thermal gradient across the optical window. This mediator provides real-time thermal data without requiring modifications to the optical window itself, resolving the contradiction between system complexity and measurement precision.
2Measurement precision
If thermocouples are integrated in the optical window, then the thermal gradient can be measured, but the transparency of the optical window is reduced and scatter is caused
Solution Approach 1:
The measurement function is extracted from the optical window itself. Instead of embedding thermocouples in the window, a separate thermal imager is used to measure the thermal gradient from the interior surface. This separation eliminates the harmful effects of embedded sensors on optical performance while maintaining measurement capability.
3Measurement precision
If thermocouples are used, then thermal gradient measurement is possible, but the complexity of the window configuration is increased
Solution Approach 1:
The measurement functionality is extracted from the window structure itself. A separate thermal imager performs the thermal gradient measurement without requiring any modifications to the window configuration, thereby maintaining window simplicity while achieving precise thermal measurements.
4Device complexity
If conventional methods are used to determine thermal gradient, then the system is simpler, but sensor performance is reduced due to thermal distortions
Solution Approach 1:
The thermal imager provides real-time feedback on the thermal gradient across the optical window. This feedback is used to dynamically adjust the optical corrector, compensating for thermal distortions and maintaining sensor performance despite varying thermal conditions during flight.
5Speed
If the optical window has complex and conformal geometries, then aerodynamic performance is optimized, but thermocouples are inadequate for measuring thermal gradients
Solution Approach 1:
A thermal imager serves as an intermediary measurement device that can accurately capture thermal gradients on complex and conformal window geometries without being constrained by the shape limitations of contact-based thermocouples. This enables precise thermal measurements on aerodynamically optimized window designs.
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 allows for precise real-time correction of thermal distortions, improving sensor performance by directly measuring thermal gradients and reducing the complexity of the optical window configuration.
Implementation Method 1
A thermal imager may be used to image an optical window from inside the window. The thermal imager may be configured to determine a real-time temperature profile of the optical window.
Implementation Method 2
During flight of the vehicle, the optical window is generally subject to mechanical and thermal stresses and a thermal gradient may be produced across the window. The resulting thermal gradient may change an optical index of refraction and optical absorption coefficients of the window materials such that the normal paths of the optical rays may be distorted.
Data Source
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AI summary
A thermal detection system for detecting a thermal profile of an optical window may be used in an airborne body that contains a sensor system. The system may include a thermal imager arranged within the airborne body for imaging a portion of the optical window and the portion may coincide with an optical path of the sensor system. The system may further include a processor in communication with the thermal imager for receiving images of the portion and determining a thermal gradient of the portion. The processor may be configured to apply corrections to active optical elements of the sensor system to accommodate for adverse thermal effects on the optical sensor that interferes with the sensor system performance.