Directional-Stiffness Mirror Socket for Precise Optical Alignment
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Solution Overview
Problem
Existing mirror sockets for optical elements in EUV lithography apparatuses introduce unwanted forces and deformations, affecting imaging quality due to inconsistent stiffness in different spatial directions.
Innovation Solution
A mirror socket with varying stiffness in different spatial directions, allowing for the optical element to be mounted without introducing forces or moments, achieved by a design with distinct geometries and materials that provide differential stiffness in the first and second spatial directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mirror sockets are adhesively bonded to the mirror with uniform stiffness in all directions, then the mounting is simple and stable, but unwanted forces and moments are introduced into the optical element causing deformations
Solution Approach 1:
The mirror socket is designed with spatially varying stiffness properties - the first stiffness in the first spatial direction is different from the second stiffness in the second spatial direction. This local differentiation of mechanical properties allows the socket to provide appropriate support in different directions while avoiding introduction of unwanted forces and moments into the optical element.
Solution Approach 2:
The mirror socket employs asymmetric stiffness distribution where the stiffness values differ between the first and second spatial directions. This asymmetric design enables the socket to accommodate the six degrees of freedom of the mirror while minimizing parasitic forces, as the different stiffnesses compensate for the asymmetric loading conditions.
2Manufacturing precision
If the mirror socket has different stiffnesses in different spatial directions, then unwanted deformations of the optical element are minimized, but the design complexity increases
Solution Approach 1:
The mirror socket implements different stiffness characteristics in different spatial directions through its structural design. The first stiffness (in the first spatial direction) is deliberately made different from the second stiffness (in the second spatial direction), allowing precise control over the mechanical response to minimize optical deformations while maintaining a manageable design complexity.
Data Source
AI summary
A mirror socket for an optical element, comprising: a centre axis; a first spatial direction oriented perpendicular to the centre axis; and a second spatial direction oriented perpendicular to the centre axis and perpendicular to the first spatial direction. The mirror socket has a first stiffness viewed in the first spatial direction and a second stiffness viewed in the second spatial direction. The first stiffness and the second stiffness have different magnitudes.