Athermal Telescope Metering Rods for Stable Focal Distance
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Solution Overview
Problem
Conventional telescope systems face challenges in maintaining a constant optical focal distance due to the coefficient of thermal expansion of metals used in their construction, leading to image blurring and potential bolt failure from thermal cycling and vibration.
Innovation Solution
The use of thermally compensating metallic materials with tailored thermal expansion coefficients, such as Ti100-AXA, Ti100-A-BNiAXB, and Ti100-A-BTaAXB, to create metering rods that maintain a constant distance between optical mirror sources and focal targets across a wide temperature range, compensating for the expansion and contraction of other materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metals are used in telescope construction, then structural strength is achieved, but thermal expansion causes optical focal distance variation and image blurring
Solution Approach 1:
The patent applies thermal expansion principles by selecting materials with specific coefficients of thermal expansion (CTE) to compensate for dimensional changes. The metering rod uses a material whose CTE is tailored to offset the expansion of other structural components, maintaining constant optical focal distance across temperature variations from -150°C to +50°C.
Solution Approach 2:
The patent employs composite material strategies by combining materials with different thermal properties. The metering rod uses a specialized alloy (Ti100-AXA, Ti100-A-BNiAXB, or Ti100-A-BTaAXB) with tailored CTE, creating a composite structural system that achieves both mechanical strength and thermal stability.
2Strength
If conventional metals are used in telescope construction, then structural strength is achieved, but thermal cycling and vibration cause bolt failure
Solution Approach 1:
The patent uses thermal expansion compensation to prevent differential expansion between connected components. By matching CTE values across joined materials, the system eliminates thermal stresses that would otherwise cause bolt loosening or failure during thermal cycling.
Solution Approach 2:
The patent changes the material parameter (CTE) of the metering rod to achieve compatibility with adjacent components. This parameter matching prevents relative movement and stress concentration at joints, thereby improving bolt reliability under thermal cycling and vibration.
3Reliability
If materials with tailored CTE are used to compensate thermal expansion, then optical focal distance stability is achieved, but material selection becomes more complex
Solution Approach 1:
The patent systematically applies thermal expansion compensation by providing specific CTE values for recommended materials. This structured approach to material selection based on thermal properties simplifies the design process while achieving the required optical stability.
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 solution ensures a stable optical focal distance over severe temperature swings, preventing image blurring and bolt failure, and is applicable in extreme environments like cryogenic assemblies.
Implementation Method 1
the coefficient of thermal expansion of metals used in their construction, leading to image blurring
Implementation Method 2
thermally compensating metallic materials with tailored thermal expansion coefficients... compensating for the expansion and contraction of other materials
Data Source
AI summary
A series tailored athermally stabilized optical (STASO) telescope system (STASOS) and method (STASOM) is disclosed. The disclosed system/method separates an optical mirror source (OMS) and an optical focal target (OFT) via a first metering rod (FMR), second metering rod (SMR), and third metering rod (TMR) where the FMR, SMR, and TMR each comprise a first retaining rod (FRR) comprised of a material having a first thermal expansion (FTE) coefficient and a second retaining rod (SRR) comprised of a material having a second thermal expansion (STE) coefficient. The FMR, SMR, and TMR are constructed so as to be athermally stabilized to ensure that the OMS and OFT remain separated at a constant or controlled distance over a predetermined temperature range by selection of appropriate FTE and STE coefficients.