Infrared Spatial Modulator for Non-Uniformity Correction
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Solution Overview
Problem
Heat-seeker missiles with IR thermal array sensors face non-uniformity issues due to varying responsitivity among pixels, leading to interference in guidance systems and the need for real-time correction to ensure accurate targeting.
Innovation Solution
A non-mechanical, scene-based non-uniformity correction system using an IR spatial modulator, such as smart glass, in the optical path of the IR sensor, which rapidly adjusts to provide uniform illumination and corrects for intensity variations by activating and deactivating to achieve real-time scene-based correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional mechanical NUC methods are used, then non-uniformity correction can be achieved, but the correction process is slow and requires mechanical movement of components
Solution Approach 1:
The patent replaces mechanical NUC methods with an optical-based solution using an IR spatial modulator that can rapidly change transmission properties without mechanical movement. The modulator uses electro-optic or liquid crystal effects to switch between transparent and scattering states, eliminating the need for mechanical shutters or moving parts while achieving faster correction speeds.
Solution Approach 2:
The IR spatial modulator provides dynamic control over the optical path by rapidly switching between transparent and scattering states. This dynamic capability allows the system to adapt to changing scene conditions in real-time, enabling correction speeds faster than mechanical systems can physically move components.
2Adaptability or versatility
If pre-flight calibration is used, then non-uniformity correction can be performed, but it cannot adapt to in-flight conditions and requires separate calibration procedures
Solution Approach 1:
The system performs self-calibration by using the scene itself as the calibration target. The IR spatial modulator scatters light from the actual scene to create a uniform reference pattern, allowing the system to automatically calculate and apply correction terms without external calibration equipment or pre-flight procedures. This eliminates calibration time loss during flight operations.
Solution Approach 2:
The system prepares correction data by analyzing scattered scene light before final image capture. By pre-processing the scattered light patterns and calculating correction terms in advance, the system can rapidly apply corrections to the actual target image without delaying the overall operation.
3Measurement precision
If the IR modulator is activated to scatter light for correction, then non-uniformity can be corrected, but the target image cannot be simultaneously captured
Solution Approach 1:
The system uses rapid periodic switching of the IR spatial modulator between transparent and scattering states. This periodic action allows the system to quickly alternate between capturing scattered light for correction and capturing the actual target image, minimizing the time penalty of performing both functions.
Solution Approach 2:
The scattered light pattern is captured and correction terms are calculated in advance before the final target image is captured. This preliminary processing of correction data allows the actual target imaging to proceed without delay, as the correction algorithms can be applied post-capture or during image processing.
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 rapid, in situ non-uniformity correction in less than one second, improving the accuracy and sensitivity of the IR imaging system by providing a spatially corrected uniform image, enhancing the missile's ability to target effectively while reducing Fixed Pattern Noise.
Implementation Method 1
The IR modulator is capable of clearly transmitting and scattering variable intensities of IR radiation from a target imaged to the focal plane array (FPA) of a thermal IR sensor
Implementation Method 2
the IR modulator is made from a smart glass, such as a liquid crystal or suspended particle device, such as an electrochromic device
Data Source
AI summary
Embodiments of an infrared spectral modulator for scene-based non-uniformity image correction are generally disclosed herein. The spectral modulator may be suitable for use in a system for navigating an object having a flight path comprising an infrared sensor having an optical path; an infrared modulator in the optical path of the infrared sensor, wherein the infrared modulator is configured to allow the infrared sensor to perform in situ, real-time, scene-based non-uniformity correction; and a guidance system within the object, wherein the guidance system can adjust the flight path of the object based on the non-uniformity correction.