Optothermally Stable Metering Structure with Absorptive Shield
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Solution Overview
Problem
Optical sensor systems in dynamic thermal environments face challenges in maintaining precise spacing and orientation of optical components due to thermal deformations and stray light interference, which limits mission operations and on-orbit observation efficiency.
Innovation Solution
A metering structure comprising a rigid strut with a highly absorptive rigid shield and multi-layer insulation, along with flexure brackets to absorb mechanical stresses and reduce thermal energy transmission, is designed to maintain optothermal stability and minimize stray light reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid metering structure is used to support optical elements, then structural strength and stability are improved, but thermal deformations cause loss of spacing and orientation precision
Solution Approach 1:
The metering structure is divided into separate functional components: rigid struts for structural support and independent thermal insulation layers for thermal management. This segmentation allows each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
Thermal insulation layers are introduced as intermediary elements between the rigid strut and the optical components. These insulation layers act as mediators that decouple the structural support function from the thermal environment, preventing thermal deformations from affecting the optical spacing and orientation.
2Stability of the object's composition
If thermal insulation layers are added to reduce thermal effects, then optothermal stability is improved, but device complexity increases
Solution Approach 1:
The patent employs thin film thermal insulation layers that provide effective thermal isolation while occupying minimal space. These thin film structures maintain optothermal stability without significantly increasing the overall device complexity or volume.
3Device complexity
If a simple metering structure is used, then device complexity is reduced, but stray light reflections increase optical noise
Solution Approach 1:
The patent applies non-reflective coatings to the thermal insulation layers, converting what would normally be reflective surfaces into absorptive surfaces. This transforms the harmful stray light reflections into beneficial absorption, reducing optical noise while maintaining a relatively simple structure.
4Loss of energy
If thermal insulation is added to the metering structure, then thermal energy transmission is reduced, but mechanical stress transmission may be compromised
Solution Approach 1:
The patent uses composite material structures where thermal insulation layers are combined with mechanically robust support elements. This composite approach allows the structure to simultaneously provide thermal isolation and maintain mechanical stress transmission capabilities through the rigid strut components.
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 solution effectively decouples thermal and mechanical stresses between the strut and shield, enhancing optothermal stability and reducing optical noise, thereby improving mission operations and observation efficiency in dynamic thermal environments.
Implementation Method 1
The MLI system is disposed between the rigid strut and the rigid shield. The MLI system surrounds the rigid strut and is substantially coextensive with the shield length. The plurality of material layers comprising the MLI are configured to at least partially thermally decouple the rigid strut from the rigid shield.
Implementation Method 2
The rigid shield has a surface finish which is highly absorptive of electromagnetic radiation in the optical spectrum. This surface finish is provided on an exterior surface of the rigid shield along the shield length.
Implementation Method 3
The flexure bracket is configured to flex so that the attachment point on the shield can move slightly relative to the attachment point on the strut. As such, the one or more flexure brackets can compensate or absorb mechanical stresses which are caused by a coefficient of thermal expansion (CTE) mismatch between the rigid shield and the strut.
Implementation Method 4
The rigid bracket advantageously includes at least one thermal isolating component which is comprised of a low thermal conductivity material and is configured to minimize transmission of thermal energy between the rigid strut and the rigid shield.
Data Source
AI summary
Metering structure includes a rigid strut configured to support an optical element. A rigid shield mounted on the strut has a shield length which is substantially coextensive with the elongated length of the rigid strut such that rigid shield substantially encloses the strut along the entire shield length. The rigid shield has a surface finish which is highly absorptive of electromagnetic radiation in the optical spectrum. One or more thermal insulating material layers comprise a multi-layer insulation (MLI) system disposed between the rigid strut and the rigid shield. Rigid and flexure brackets secure the rigid shield to the strut.