Cryogenic Optical System Inside Dewar for Compact Thermal Imaging
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Solution Overview
Problem
Traditional thermal imaging systems with optical systems and dewars are excessively long and heavy, making them unsuitable for applications requiring compactness, such as portable surveillance and missile warning systems, due to the separate lengths of the optical system and dewar, and the issue of optical misalignment and fracture from differential material shrinkage at cryogenic temperatures.
Innovation Solution
Positioning the optical system entirely within the dewar, using components made of a single material to prevent misalignment and fracture, and employing a collimator for refocusing, allowing the system to maintain functionality and reduce overall size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the optical system is positioned outside the dewar, then the system is easier to manufacture and maintain, but the overall system length and weight increase excessively
Solution Approach 1:
The patent merges the optical system with the dewar by positioning the optical system entirely inside the dewar. This integration eliminates the need for separate mounting structures and reduces the overall system length and weight, directly resolving the contradiction between compactness and manufacturing complexity.
Solution Approach 2:
The optical system is nested within the dewar structure, with optical components positioned inside the cryogenic enclosure. This nesting arrangement allows the optical system to benefit from the dewar's protective environment while minimizing the external footprint of the entire system.
2Reliability
If different material types are used in the optical system, then the optical system can be optimized for different functions, but the system fractures or misaligns due to differential shrinkage at cryogenic temperatures
Solution Approach 1:
The patent applies homogeneity by using optical components made from the same material type (e.g., all silicon or all germanium). This ensures uniform thermal contraction behavior at cryogenic temperatures, preventing differential shrinkage that would cause misalignment or fracture, thus maintaining optical reliability.
Solution Approach 2:
The patent changes the material selection parameter from diverse materials to uniform materials. This parameter change ensures that all optical components respond identically to cryogenic temperature changes, eliminating differential thermal contraction and maintaining structural integrity.
3Reliability
If the optical system is sealed inside the dewar, then the system is protected from environmental changes, but the optical system cannot be refocused after sealing
Solution Approach 1:
The patent applies preliminary action by performing all focusing adjustments and optical alignments before sealing the dewar. The optical system is configured and focused externally, then the dewar is sealed to protect the system from environmental changes. This preliminary configuration ensures the system remains focused despite being sealed.
Solution Approach 2:
The patent replaces mechanical refocusing mechanisms with a fixed optical design that is pre-configured for focusing. By eliminating movable mechanical components that would require access for adjustment, the system achieves both environmental protection through sealing and maintained focus through rigid, pre-aligned optical paths.
4Weight of stationary object
If the optical system is positioned inside the dewar, then the overall system size and weight are reduced, but the optical system is exposed to extreme cold temperatures
Solution Approach 1:
The patent uses optical materials with appropriate cryogenic properties (such as silicon or germanium) that maintain their optical characteristics at low temperatures. This material homogeneity ensures the optical system functions reliably in the cold environment while benefiting from the reduced system weight.
Solution Approach 2:
The patent changes the operating temperature parameter to cryogenic levels and selects materials and optical designs optimized for this temperature range. This parameter change enables the system to achieve weight reduction while maintaining optical performance through cryogenic-optimized material selection and design.
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 reduces the system's size and weight, enhances sensitivity by minimizing external radiation, and enables correct focusing despite cryogenic temperatures, making it suitable for applications with limited space and temperature sensitivity.
Implementation Method 1
A thermal imaging system traditionally consists of a detector, or collection of detectors, sensitive to infrared radiation
Implementation Method 2
an optical system capable of receiving and focusing said radiation onto the detector
Implementation Method 3
a vacuum enclosure is required to minimize thermal losses though heat conduction
Implementation Method 4
the infrared detector is often cooled, typically to cryogenic temperatures
Data Source
AI summary
According to one embodiment of the present invention, a system for viewing an area includes a dewar and an optical system positioned within the dewar. The dewar permits operation of the flux detector at cryogenic temperatures, in some embodiments. The optical system includes an infrared radiation system capable of focusing one or more light beams. The inclusion of the optical system within the cryogenic space of the dewar allows reduction of the overall system length and weight, if desired.