Optical Assembly Diffusion Bonding with Removable Liner
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Solution Overview
Problem
Existing optical assemblies face challenges in achieving strong and durable bonding between optical films and optical elements while maintaining high reflectance and optical interference properties, especially when the optical elements are molded onto optical stacks with varying thickness and curvature.
Innovation Solution
The integration of an optical film with alternating polymeric layers, which are diffusion bonded to the optical element, ensuring a stronger bond than interlayer bonding and maintaining high reflectance across a significant area, with the optical element's melting temperature being substantially larger than the film's glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the optical element is molded onto the optical film, then the bonding strength between optical film and optical element is improved, but the optical film may suffer damage during the molding process
Solution Approach 1:
A liner is introduced as an intermediary layer between the optical film and the molding cavity. The liner protects the optical film from direct contact with the mold cavity and ejection mechanisms, preventing damage during the molding process while still allowing the optical element to bond to the optical film.
Solution Approach 2:
The liner is placed on the optical film before the molding process to provide protective cushioning. This pre-protection measures prevents potential damage from the molding and ejection processes, ensuring the optical film maintains its integrity throughout manufacturing.
2Reliability
If a liner is used to protect the optical film during molding, then the optical film integrity is improved, but the device complexity increases
Solution Approach 1:
The liner is designed to be easily removable after serving its protective function during molding. The simple design allows the liner to be peeled off without requiring additional tools or complex removal mechanisms, reducing the overall system complexity while maintaining protection during the critical molding phase.
3Strength
If the optical element melting temperature is much higher than the optical film glass transition temperature, then the bonding strength is improved through diffusion bonding, but the processing temperature control becomes more difficult
Solution Approach 1:
The molding process utilizes temperature as a critical parameter, heating the optical film to above its glass transition temperature to enable diffusion bonding with the optical element. The process maintains temperature within a specific window (above Tg but below the element's melting point) to achieve optimal bonding while preventing damage, demonstrating precise parameter control.
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 approach results in optical assemblies with enhanced bonding strength and optical performance, where the optical film retains high reflectance and interference properties even after molding, with minimal damage during liner removal and varying optical retardance across the element.
Implementation Method 1
The optical film includes a plurality of alternating polymeric layers reflecting or transmitting light primarily by optical interference
Implementation Method 2
The optical film is diffusion bonded to the optical element. The bonding of the optical film to the optical element is stronger than an interlayer bonding between at least one pair of immediately adjacent layers in the optical film
Data Source
AI summary
An optical assembly including an optical element insert molded directly onto an optical stack is provided. The optical stack includes an optical film and may include a liner with the optical film being disposed between the optical element and the liner. The liner, if included, is removable from the optical film without substantial damage to the optical film. An outermost layer of the optical film may be diffusion bonded to a major surface of the optical element.