Athermal Imaging Optics Mounting for Axial Focus Stability
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Solution Overview
Problem
Existing imaging systems face challenges in maintaining optical focus and stability due to thermal expansion of components made from different materials, leading to unwanted focal shifts and position changes with temperature variations.
Innovation Solution
An imaging apparatus with a compensation unit arranged between the housing and optical arrangement, utilizing materials with specific thermal expansion coefficients to counteract and minimize axial position changes, combined with athermal mounting of the imaging sensor using isotropic materials and decoupling mechanisms to reduce stress and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different materials are used for housing and optical components, then manufacturing flexibility and component compatibility are improved, but thermal expansion differences cause focal shifts and position changes with temperature variations
Solution Approach 1:
The patent applies thermal expansion by selecting materials with different coefficients of thermal expansion (CTE) for the housing and optical components. The housing is made of a material with higher CTE than the optical components, causing the housing to expand more with temperature increases. This differential expansion automatically compensates for thermal focal shifts, maintaining optical focus stability across temperature variations without requiring active compensation mechanisms.
Solution Approach 2:
The patent employs composite material selection strategy where the housing is constructed from materials with specific thermal properties that differ from the optical components. This composite approach allows the housing to serve dual functions: providing mechanical support and simultaneously compensating for thermal effects through controlled differential expansion, thus maintaining both manufacturing flexibility and optical stability.
2Reliability
If compensation units are added to counteract thermal expansion, then optical focus stability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service by designing the housing and mounting structure to automatically compensate for thermal expansion without requiring external compensation units or active control systems. The differential thermal expansion between the housing material and optical component materials creates a self-regulating mechanism that maintains optical focus stability passively, eliminating the need for additional compensation hardware and reducing overall device complexity.
3Stability of the object's composition
If imaging sensor is rigidly mounted to housing, then mechanical stability is improved, but thermal stress and displacement increase with temperature changes
Solution Approach 1:
The patent applies local quality by differentiating the mounting characteristics at different locations and levels. The imaging sensor is mounted with compliant or flexible mounting features that allow for thermal expansion and contraction, while the overall housing structure maintains rigid stability. This localized compliance at the sensor mounting interface accommodates thermal movements without compromising the mechanical stability of the entire system, preventing thermal stress and displacement.
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 ensures minimal axial position changes of the image plane, maintaining optical stability and focus within a wide temperature range, achieving sub-pixel accuracy and precision.
Implementation Method 1
utilizing materials with specific thermal expansion coefficients to counteract and minimize axial position changes
Implementation Method 2
athermal mounting of the imaging sensor using isotropic materials and decoupling mechanisms to reduce stress and displacement
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
Imaging optical systems usually comprise various components like a sensor, optics or a supporting structure. Optics of the imaging optical system may consist of a single lens or a mirror. In practice, the optics consist of combination of different components and thus form a multi-component optical system. In the multi-component optical system the components consist of different materials. An imaging apparatus 1 is disclosed, comprising: a housing 3, an imaging sensor 2, whereby the imaging sensor 2 is arranged in the housing 3, an optical arrangement 6 for projecting an image onto the imaging sensor 2 in an image plane P, whereby the optical arrangement 6 is coupled to the housing 3, a compensation unit 10 to athermalize the axial position of the image plane P, whereby the compensation unit 10 is arranged between the housing 3 and the optical arrangement 6.