Kinematic Optical Mount with Strut Flexures
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Solution Overview
Problem
Conventional lens mounting methods for microlithography and precision optical applications often result in overconstraint and purity of motion issues, limiting their effectiveness due to complexity, precision fabrication requirements, and thermal expansion differences in materials, necessitating a solution that allows precise axial adjustment while constraining rotational and translational movements orthogonal to the optical axis.
Innovation Solution
A mechanical constraint pattern using strut flexures between members, with a six-constraint arrangement and lever elements, allowing precise axial adjustment while preventing motion in other directions, and enabling monolithic fabrication to minimize thermal effects and assembly complexities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lens mounting methods are used, then assembly is straightforward, but motion purity is compromised due to overconstraint and parasitic effects
Solution Approach 1:
The patent employs flexure elements that provide dynamic, compliant constraints rather than rigid fixed constraints. The flexures allow controlled motion along the optical axis while elastically constraining parasitic rotations and transverse translations, resolving the contradiction between motion purity and assembly simplicity by replacing static overconstraint with dynamic selective constraint.
Solution Approach 2:
The invention changes the mechanical parameter of constraint rigidity by using flexure elements with specific stiffness characteristics. These flexures are designed to be compliant in the desired motion direction (axial translation) while maintaining stiffness against unwanted motions (rotations and transverse translations), thereby achieving pure motion without complex assembly procedures.
2Manufacturing precision
If multiple interconnecting parts with springs and flexures are used for axial adjustment, then axial positioning is achieved, but device complexity increases significantly
Solution Approach 1:
The patent merges multiple functions (axial positioning, rotational constraint, and transverse translation constraint) into a single integrated flexure-based mounting structure. Rather than using separate springs, flexures, and hinges as in conventional solutions, the invention combines these constraints into unified flexure elements that perform multiple functions simultaneously, achieving precise axial positioning with fewer parts.
Solution Approach 2:
The flexure elements serve multiple functions: they enable axial translation, constrain rotations about all three axes, and prevent transverse translations. This multi-functionality eliminates the need for separate components for each constraint, reducing device complexity while maintaining manufacturing precision for axial positioning.
3Stability of the object's composition
If different materials with different CTEs are used for components and fasteners, then thermal effects are minimized through careful specification, but assembly complexity and potential overconstraint increase
Solution Approach 1:
The patent employs homogeneity by using the same material for both the optical element holder and the flexure elements. This eliminates thermal expansion mismatches and differential thermal effects that would arise from joining dissimilar materials, thereby achieving thermal stability without the assembly complexity and overconstraint issues associated with multi-material constructions.
Solution Approach 2:
The invention uses a composite flexure structure made from a single homogeneous material that provides both structural support and compliant motion. This single-material approach avoids the thermal expansion coefficient mismatches inherent in multi-material assemblies, achieving thermal stability while simplifying assembly procedures and eliminating overconstraint problems.
4Ease of manufacture
If static mounting solutions are used, then assembly is simple, but adjustment capability for focus and magnification is limited
Solution Approach 1:
The patent transforms the static mounting structure into a dynamic adjustable system by incorporating flexure elements that allow controlled axial motion. The flexures provide a compliant mechanism that enables focus and magnification adjustments while maintaining simplicity in the overall assembly approach, bridging the gap between static simplicity and dynamic adjustability.
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 provides a compact, high-precision optical mount that allows controlled axial positioning of optical elements along the optical axis, constraining unwanted movements, and reduces mechanical stress and assembly errors, suitable for microlithography and other precision applications.
Implementation Method 1
strut flexures that extend between first and second members
Data Source
Figure 1~2A
Figure 2B~3
Figure 4~5A
AI summary
A positioning apparatus for providing relative movement between a first member and a second member has a lever element pivotably coupled to the first member along a fulcrum member and has an actuator arm and a positioner arm. First and second flexure elements extend between the positioner arm of the lever element and the second member. An actuator is coupled to the actuator arm of the lever element.