Patterned Interface Bonding for Optical Assemblies
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Solution Overview
Problem
Existing methods for fixing inhomogeneous optical parts, such as beam splitters, often result in unwanted bonding and stress due to thermal expansion differences, leading to optical degradation or physical damage, and are costly and difficult to implement.
Innovation Solution
A pattern control element with a non-stick surface, such as PTFE tape, is applied to specific areas of the interface to control the bonding between parts, preventing unintended adhesion and allowing precise attachment without altering the parts themselves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied to the entire interface area to ensure strong bonding, then bonding strength is improved, but thermal stress and optical degradation occur due to unwanted bonding in areas with different CTE
Solution Approach 1:
The interface area is divided into different zones with different bonding properties. The holder part has adhesive areas and non-adhesive areas created by relief structures (protrusions and recesses). This local differentiation allows bonding in some areas while preventing bonding in others, resolving the contradiction between overall bonding strength and local thermal stress prevention.
2Ease of operation
If the entire interface area is used for bonding to maximize attachment, then fixation strength is improved, but stress from thermal expansion differences causes detachment or deformation
Solution Approach 1:
The continuous interface area is segmented into multiple discrete adhesive zones separated by non-adhesive relief structures. This segmentation reduces the cumulative thermal stress by creating gaps that allow differential expansion while maintaining fixation stability through distributed bonding points.
3Reliability
If traditional methods like cutting away bonding areas or using gaskets are used to prevent unwanted bonding, then thermal stress is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The non-adhesive features (relief structures) are merged into the holder part itself during manufacturing, rather than being separate components like gaskets or masks. This integration reduces assembly complexity while achieving the same stress-reduction effect, as the relief structures are formed as part of the molding process.
4Manufacturing precision
If geometric changes are made to parts to control bonding areas, then unwanted bonding is prevented, but BOM cost and handling cost increase
Solution Approach 1:
The bonding area control is achieved by changing the geometric parameters of the holder part (creating relief structures with specific heights and widths) rather than modifying the attachment part. This parameter change approach allows precise control of bonding areas while keeping the overall part geometry simple and compatible with standard manufacturing processes.
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 solution effectively prevents unwanted bonding and stress, maintaining the reliability and optical integrity of the assembly by allowing controlled attachment, reducing costs and complexity compared to traditional methods.
Implementation Method 1
the pattern control element comprises a non-stick surface
Implementation Method 2
the attachment part is attached to the holder part with an adhesive in an interface area
Data Source
Figure 1a~2
AI summary
Disclosed is fixation by means of any type of adhesive of an assembly consisting of two or more sub-parts internally joined rigid together, e.g. a cemented doublet, or - as detailed in an example - a beam splitter. It is often beneficial to constrain the fixation to only one of the subparts in order to prevent either optical degradation of the performance or even physical damages due to thermal stress. The invention consists in limiting the adhesive area by adding a patterned - non adhesive - element to part of the interface.