Low-stress lens mount assembly for UV optics
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Solution Overview
Problem
Existing lens carriers for high-power UV and DUV objectives face challenges in maintaining low-stress retention of optical elements, as they often result in misalignment and deformation due to dynamic and thermal loads, and require precise manufacturing tolerances and frictional engagement, which can impair imaging quality.
Innovation Solution
A mount assembly with a monolithic mount ring featuring retaining arms of unequal lengths, where three arms with a first length contact the end face for axial holding and additional arms with a second length contact the circumferential surface for radial holding, utilizing adhesive bonding and radial elasticity to minimize stress and misalignment, while allowing thermal expansion without radial tensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If frictional engagement is used to hold the lens in the mount, then the lens position is determined, but imaging quality is impaired due to deformation and misalignment
Solution Approach 1:
The patent replaces the friction-based mechanical holding system with an adhesive bonding system. The adhesive layer bonds the lens to the mount ring, eliminating frictional forces that cause deformation and misalignment while maintaining precise lens positioning. This substitution of mechanical friction with chemical bonding resolves the contradiction between position determination and imaging quality.
2Stability of the object's composition
If the lens is pressed against the retaining projection, then axial position is fixed, but lens deformation occurs on the optically active surface
Solution Approach 1:
The patent extracts the pressing function from the optically active surface of the lens. Instead of pressing the lens at its active surface, the adhesive bonding system distributes holding forces across the lens periphery and mount structure, eliminating localized deformation at the optically critical surface while maintaining axial position stability.
Solution Approach 2:
The adhesive layer acts as a flexible bonding film that distributes mechanical stresses uniformly across the lens-mount interface. This flexible bonding mechanism provides axial position stability without concentrating forces that would deform the lens, particularly avoiding pressure on the optically active surface.
3Adaptability or versatility
If radial clearance fit is used to allow thermal expansion, then thermal expansion is accommodated, but misalignment occurs under dynamic loads
Solution Approach 1:
The patent merges the functions of thermal expansion accommodation and dynamic load stabilization into a single adhesive bonding system. The adhesive layer provides both the compliance needed for thermal expansion and the bonding strength to prevent misalignment under dynamic loads, eliminating the need for separate clearance fit mechanisms.
Solution Approach 2:
The adhesive bonding system creates a composite structure between the lens and mount ring that combines the properties of both materials with the bonding interface. This composite connection allows differential thermal expansion while maintaining structural integrity and alignment stability under dynamic conditions, resolving the contradiction between adaptability and stability.
4Force
If spring forces are used to hold the lens, then axial retention is achieved, but stress states in the lens change with thermal expansion
Solution Approach 1:
The patent replaces the spring-based mechanical retention system with an adhesive bonding system. The adhesive provides continuous axial retention force without the cyclic loading and stress concentration inherent in spring mechanisms. This eliminates the problematic stress states that arise when spring forces interact with thermally expanding lens materials.
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 design reduces the need for precise manufacturing tolerances and eliminates radial retaining forces on the lens, maintaining low-stress retention and improving imaging quality by compensating for thermal expansion and dynamic loads through adaptive elasticity, thereby enhancing the stability and accuracy of the lens positioning.
Implementation Method 1
at least two of the retaining arms are bonded to the element
Implementation Method 2
In order also to enable a radial thermal expansion of the lens without radial tensions occurring in the lens which can lead to dramatic impairments in optical imaging
Implementation Method 3
the free ends contact the element... utilizing adhesive bonding and radial elasticity to minimize stress and misalignment
Implementation Method 4
dynamic loads can be damped
Data Source
AI summary
Mount assembly with a monolithic mount formed by a mount ring with a plurality of retaining arms with free ends and an element, which retaining arms are arranged concentrically around the axis of symmetry of the mount ring and extend at least partially in axial direction. Three of the retaining arms contact an end face formed at the element and hold the element axially, while the other retaining arms are bonded to a circumferential surface formed at the element and prevent the element in particular from rotating.