Removable Lens Stack With Fluoropolymer Coating
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Solution Overview
Problem
Conventional tearoff lens stacks with moth-eye coatings face issues with high peel strength due to adhesive filling in around the bumps, making it difficult to remove layers and compromising visibility by increasing internal reflection.
Innovation Solution
A removable lens stack design featuring a base layer with a moth eye coating on one side and a fluoropolymer coating on the other, with additional removable lens layers also having moth eye coatings and fluoropolymer coatings that interlock mechanically, reducing peel strength to less than 100 grams per inch and maintaining high visible light transmission by eliminating refractive index interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If moth-eye coatings are used to reduce reflection, then visible light transmission is improved, but peel strength increases making layer removal difficult
Solution Approach 1:
The lens stack is divided into multiple removable layers, each with its own moth-eye coating. The fluoropolymer coating on each layer segments the adhesive bonding, creating discrete bonding zones that allow controlled peeling. This segmentation enables layers to be removed individually while maintaining the anti-reflective properties of the moth-eye structures.
Solution Approach 2:
The fluoropolymer coating changes the physical and chemical parameters of the layer surface, creating a low-surface-energy material that resists adhesive wetting. This parameter change in surface energy and chemistry reduces the adhesive's ability to fill in around the moth-eye bumps, thereby reducing peel strength while preserving the optical benefits.
2Stability of the object's composition
If adhesives are used to bond lens layers, then layer stability is improved, but peel strength increases making removal difficult
Solution Approach 1:
The fluoropolymer coating is applied locally to specific regions of each lens layer, creating zones with different adhesive interaction properties. This local quality change ensures that adhesive bonds are formed in controlled areas while other areas remain easily separable, allowing layers to be removed without compromising overall stack stability during use.
Solution Approach 2:
Each lens layer is constructed as a composite material system combining the base lens material, moth-eye coating for optical performance, and fluoropolymer coating for adhesive control. This composite structure integrates multiple material properties to simultaneously achieve stability during use and ease of removal when needed.
3Strength
If conventional adhesives are used between layers, then bonding strength is improved, but internal reflection increases
Solution Approach 1:
The fluoropolymer coating acts as an intermediary layer between the lens material and the adhesive. This intermediary has optical properties that match well with both the lens material and the adhesive, reducing refractive index mismatches and minimizing internal reflection at the bonding interfaces while still allowing adequate bonding strength.
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 allows for easy removal of layers without tearing additional layers, maintaining high visibility with visible light transmission greater than 95% and reducing reflection, while avoiding the use of tacky adhesives that increase peel strength.
Implementation Method 1
Each of the fluoropolymer coatings may be molded to fit the moth eye coating of the immediately preceding layer
Implementation Method 2
moth-eye (ME) coatings, which simulate the anti-reflective properties of a moth's eye by providing a pattern of microscopic bumps that effectively eliminate the index of refraction interface between the lens and the air
Data Source
AI summary
A removable lens stack includes a base layer, a first removable lens layer, and a second removable lens layer. The base layer may include a substrate and a moth eye coating. The first removable lens layer may include a substrate, a single or multi-layer interference antireflective coating on a first side of the substrate, and a fluoropolymer coating on a second side of the substrate. The first removable lens layer may be stacked on top of the base layer with the fluoropolymer coating being molded to fit the moth eye coating. The second and any subsequent removable lens layer may include a substrate, a single or multi-layer interference antireflective coating on a first side of the substrate, and an acrylic or polyurethane adhesive on a second side of the substrate. The second removable lens layer may be stacked on top of the first removable lens layer and so on.