Thermally Responsive Actuator Collar for Optical Focus Compensation
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Solution Overview
Problem
Optical systems, particularly those with large apertures and high magnification, are sensitive to temperature variations, leading to significant impact on image quality due to component expansion or contraction, especially in airborne platforms operating over a wide temperature range.
Innovation Solution
A thermally-responsive actuator assembly with actuators integrated into a collar around the optical axis, comprising beams and rods of differing thermal expansion coefficients, compensating for temperature-induced changes by varying the relative position of optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If optical components are rigidly mounted to maintain stable positioning, then structural strength is improved, but thermal expansion causes loss of focus and image quality degradation
Solution Approach 1:
The patent changes the physical state of the mounting structure by introducing a compliant mechanism that allows controlled dimensional changes in response to temperature variations. The actuator assembly transforms the rigid mounting into a dynamically adaptable structure that maintains optical alignment despite thermal expansion of optical components.
Solution Approach 2:
The patent directly addresses thermal expansion by using a thermally-responsive actuator assembly that compensates for the expansion or contraction of optical components. The actuator includes materials with different thermal expansion coefficients that generate compensating forces to maintain focus accuracy when temperature changes cause dimensional changes in optical elements.
2Manufacturing precision
If thermal compensation mechanisms are added to maintain focus accuracy, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent merges the thermal compensation function with the mechanical mounting structure by integrating the actuator assembly into the collar that already supports the optical components. This combination eliminates the need for separate compensation mechanisms and reduces overall system complexity while maintaining focus accuracy.
Solution Approach 2:
The actuator assembly operates autonomously by utilizing the temperature changes themselves as the driving force for compensation. The thermally-responsive materials automatically expand or contract in response to temperature variations, generating the necessary forces to maintain optical alignment without requiring external control systems or additional actuators.
3Stability of the object's composition
If actuator materials with high thermal expansion coefficients are used to compensate for component contraction, then focus stability is improved, but manufacturing precision of the actuator itself becomes more difficult
Solution Approach 1:
The patent employs composite material construction in the actuator assembly, combining materials with different thermal expansion coefficients to achieve the desired net thermal response. This allows tuning of the overall thermal behavior to match the compensation requirements while using materials that are more forgiving in manufacturing.
Solution Approach 2:
The patent applies different material properties to different parts of the actuator assembly to achieve the desired thermal compensation effect. By localizing high thermal expansion coefficient materials in specific regions where they provide maximum benefit while using more manufacturable materials in other regions, the design balances focus stability with manufacturing feasibility.
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
Maintains accurate focus and image quality over a wide temperature range by adjusting the spacing of optical components, using a pre-stressed actuator design with a negative effective thermal expansion coefficient.
Implementation Method 1
the first and second coefficients of thermal expansion differing such that variation in temperature causes deformation of the actuators, thereby varying the height of the actuators
Data Source
AI summary
A thermally-compensated optical system (30) has a thermally-responsive actuator assembly (38) between first and second optical components (32,34) arrayed along an optical axis. The actuator assembly has actuators (10) integrated into a collar encircling the optical axis. Each actuator has two interconnected beams (12a,12b) from a first 5 material and a rod (18) associated with the ends of both beams such that a distance between the ends is determined by a length of the rod. The rod is formed from a second material having a coefficient of thermal expansion different from that of the first material such that a variation in temperature causes deformation of the actuators, thereby varying a height of the actuators according to an effective coefficient of thermal expansion with 10 a magnitude greater than that of both materials. This adjusts a relative position of the first and second components along the optical axis.