Continuous Variable Aperture for Forward Looking Infrared Cameras
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Solution Overview
Problem
Infrared cameras with non-circular exit pupils require a corresponding non-circular variable aperture to match the f-number of the front optics, but existing solutions provide limited discrete aperture sizes and are discontinuous, failing to maintain the desired aperture shape as the aperture size changes.
Innovation Solution
A non-circular adjustable continuous aperture is formed using L-shaped or T-shaped blades that maintain the aspect ratio and shape of the aperture, with additional C-shaped blades rounding corners, allowing for continuous adjustment of aperture size while keeping the shape constant, including the option to completely block radiation as a cold shutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If discrete aperture sizes are used in existing solutions, then the aperture can be adjusted to match f-number, but the aperture shape cannot be maintained as size changes
Solution Approach 1:
The patent applies the dynamics principle by using a continuous variable aperture mechanism where blades can move smoothly between positions to change aperture size while maintaining a consistent non-circular shape. The aperture transitions from discrete steps to continuous adjustment, allowing the shape to remain stable throughout the range of motion.
Solution Approach 2:
The patent changes the parameter of aperture size continuously rather than in discrete steps. By implementing a mechanism that allows smooth variation of the aperture dimensions while preserving the non-circular geometry, the system maintains shape consistency across the entire adjustment range.
2Stability of the object's composition
If multiple aperture mechanisms are used to maintain shape during size adjustment, then aperture shape can be maintained, but device complexity increases
Solution Approach 1:
The patent merges multiple blade elements into a unified aperture mechanism where all blades are controlled simultaneously to maintain the non-circular shape. Instead of using separate mechanisms for different aperture sizes, a single integrated system adjusts all blades together to preserve shape consistency.
Solution Approach 2:
The patent creates a universal aperture mechanism that can maintain a consistent non-circular shape across all aperture sizes. The same mechanism structure handles both shape preservation and size adjustment functions, eliminating the need for multiple specialized mechanisms.
3Device complexity
If the aperture does not match the exit pupil shape, then the mechanism is simpler, but unwanted radiation enters the detector
Solution Approach 1:
The patent applies local quality by creating an aperture with a specific non-circular shape that matches the exit pupil geometry. The aperture is designed with differentiated local characteristics (non-uniform shape) to precisely block unwanted radiation paths while maintaining simplicity in the overall control mechanism.
Data Source
AI summary
A continuous variable non-circular aperture for an infra-red camera is formed by a plurality of positionable metal blades arranged to define there between an aperture of non-circular shape. A rotatable actuator plate positions the blades. Actuator rotation in one direction moves the metal blades to increase the size of the non-circular aperture without changing the non-circular shape of the aperture and vice-versa when the actuator plate is rotated in the opposite direction also maintaining the non-circular aperture shape. A preferred non-circular shape for a continuous variable aperture now possible is a rectangle; another is configured as a racetrack.