Hot Stop Aperture Assembly for Stable Thermal Imaging Bias Control
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Solution Overview
Problem
Thermal imaging systems face bias issues due to external thermal energy entering the camera when the optical field of view exceeds the camera's view, especially in environments where apertures cannot be substantially cooled, leading to transient temperature variations that affect imaging accuracy.
Innovation Solution
A hot stop aperture fixture is introduced, comprising a hot aperture and a cold aperture thermally isolated by a thermal isolation block, with controlled heat sinks to stabilize the cold aperture's temperature, minimizing bias effects through thermal isolation and active temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the camera view is widened to capture more target area, then the field of view coverage is improved, but external thermal energy enters the camera causing temperature measurement bias
Solution Approach 1:
A cold stop aperture is introduced as an intermediary component between the target and the camera. This aperture is cooled to a temperature close to absolute zero, acting as a thermal mediator that blocks external thermal energy from reaching the camera sensor while allowing the camera to maintain a wide field of view for comprehensive target coverage.
2Measurement precision
If a cold stop aperture is used to block external thermal energy, then temperature measurement bias is reduced, but the aperture temperature becomes sensitive to environmental transient variations
Solution Approach 1:
A thermal mass is introduced to pre-absorb and store thermal energy before it can affect the cold stop aperture temperature. This thermal mass acts as a buffer that anticipates and absorbs transient thermal variations, maintaining stable aperture temperature even when environmental conditions change rapidly.
Solution Approach 2:
The thermal mass serves as a cushioning element that absorbs and dampens transient thermal shocks from the environment. By placing this thermal buffer beforehand, the system protects the cold stop aperture from temperature fluctuations caused by external thermal events, ensuring consistent measurement conditions.
3Stability of the object's composition
If thermal mass is added to stabilize aperture temperature, then temperature stability is improved, but the device complexity increases
Solution Approach 1:
The cold stop aperture and thermal mass are merged into a single integrated fixture assembly. This combination allows the thermal mass to be directly coupled with the aperture structure, simplifying the overall device while maintaining temperature stability. The integrated design reduces the number of separate components and assembly steps required.
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
The hot stop aperture fixture stabilizes the cold aperture's temperature, reducing bias and enhancing thermal imaging accuracy by maintaining a consistent cold stop temperature, even in environments with varying heat loads.
Implementation Method 1
The hot aperture is thermally isolated from the cold aperture
Implementation Method 2
reducing bias effects of background radiation on the thermal images of the target
Data Source
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AI summary
A system (100) includes a camera (105) configured to detect thermal radiation (120) emitted from a target (125). The system (100) also includes an optical assembly (110) configured to be disposed between the camera (105) and the target (125). The system (100) further includes a hot stop assembly (115) disposed between the camera (105) and the optical assembly (110). The hot stop assembly (115) includes a hot aperture (130) having a first surface (160) configured to face the target (125) and a second surface (165) configured to face an interior portion of the hot stop assembly (115). The hot stop assembly (115) also includes a cold aperture (140) having a first surface (170) configured to face the camera (105) and a second surface (175) configured to face the interior portion of the hot stop assembly (115). The hot aperture (130) is thermally isolated from the cold aperture (140) and reduces transient temperature changes from the environment on the images.