Cryogenic Shutter Assembly Thermal Stability
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Solution Overview
Problem
Imaging devices operating at cryogenic temperatures in high-vacuum environments face challenges with thermal stability due to temperature variations, particularly when using shutters with interleaved iris designs, which result in significant wait times for stabilization and degraded performance.
Innovation Solution
A shutter assembly with sliding aperture blades and a thermally isolated drive mechanism, where the blades maintain thermal contact with conductive rails and are driven by a mechanism isolated from the blades except during positioning, ensuring minimal temperature change (≤10K) and maintaining a 200K differential from the drive mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If interleaved iris design with multiple blades is used to create variable aperture, then aperture shape control is improved, but thermal stability deteriorates due to friction heat and poor thermal conduction from ceramic coating
Solution Approach 1:
The shutter is divided into multiple separate blades that can be independently positioned along rails, allowing each blade to be controlled individually to create the variable aperture shape while maintaining thermal isolation between blades through the vacuum environment
Solution Approach 2:
A vacuum environment acts as a thermal intermediary, providing thermal isolation between the shutter blades and the drive mechanism. The vacuum prevents heat transfer from the warmer drive mechanism to the cryogenic shutter blades, maintaining thermal stability during operation
2Ease of operation
If mechanical drive mechanism is directly coupled to shutter blades, then positioning control is improved, but thermal stability deteriorates due to heat transfer from drive mechanism
Solution Approach 1:
The vacuum environment serves as a thermal intermediary that decouples the thermal paths between the drive mechanism and shutter blades while allowing mechanical coupling for positioning control. This enables independent control of mechanical positioning and thermal management
Solution Approach 2:
The thermal coupling between the drive mechanism and shutter blades is extracted by utilizing the vacuum environment. The mechanical connection remains for positioning, but the thermal path is removed, allowing the shutter blades to maintain cryogenic temperatures independent of the warmer drive mechanism
3Reliability
If ceramic coating is applied to shutter blades, then durability in vacuum environment is improved, but thermal conduction deteriorates causing large temperature changes
Solution Approach 1:
The ceramic coating is applied selectively to specific surfaces of the shutter blades where vacuum environment durability is most critical, while other surfaces maintain different thermal properties. This localized application optimizes both durability and thermal performance in different regions of the same component
4Speed
If shutter temperature varies more than 10K during actuation, then aperture positioning speed is improved, but imaging performance deteriorates requiring wait period
Solution Approach 1:
The vacuum environment acts as a thermal intermediary that prevents heat transfer to the shutter blades during rapid actuation, allowing fast aperture positioning without significant temperature rise. This enables both high-speed positioning and maintained imaging performance without requiring wait periods
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 shutter assembly provides continuous thermal stability at cryogenic temperatures, allowing immediate use of the imaging device after aperture changes without significant wait times, ensuring high-definition performance by minimizing thermal fluctuations.
Implementation Method 1
the first shutter member and the second shutter member maintain a thermal contact with the at least one side rail in all positions
Implementation Method 2
the at least one drive member is thermally isolated from the first shutter member and the second shutter member except when the at least one drive member drives the at least one positioning member
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A shutter assembly (12) comprising a first planar member (70) and a second planar member (72) opposed from one another and forming a sleeve having a cavity (80) therebetween, the sleeve having a pair of side rails (78) adjacent the cavity along sides of the sleeve. A first shutter member (14) having a first end (92) is disposed in the cavity and slidingly disposed along one of the side rails, and a second shutter member (14) having a second end (92) is disposed in the cavity and slidingly disposed along the other side rail. The first end is opposed to the second end and is configured to be selectively advanced towards, and retracted from, the second end so as to define an aperture (15) therebetween having a first shape when disposed in a first position, and wherein the aperture has a second larger shape when the first end is disposed in a second position. The first shutter member and the second shutter member maintain a thermal contact with the side rails and the planar members in all positions. The shutter assembly is well suited to be used at a cryogenic temperature and in a high vacuum environment.