Plasma Nanostructured Anti-Fog Optical Element

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Solution Overview

Problem

Optical elements made of glass or plastic face issues with condensation and reflection in humid environments, leading to impaired transmission, and existing anti-fog and antireflection solutions often compromise water absorption or result in undesirable color effects when light is incident at angles.

Innovation Solution

A method involving a plasma etching process to create a nanostructure on an anti-fog polymer layer, which extends into the layer's depth, combined with a thin oxide layer and a transparent protective layer, and optionally a hydrophobic layer, to achieve effective anti-reflective and anti-fogging properties without compromising water absorption or causing color issues at oblique light incidence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a porous oxide layer or interference layer system is applied to achieve antireflection, then reflection is reduced, but the water absorption capability of the anti-fog polymer layer is impaired

Engineering Contradiction:
ImprovereflectionVSAvoidwater absorption capability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies a plasma-generated nanostructure with porous characteristics directly on the anti-fog polymer layer surface. This porous nanostructure achieves antireflection through light scattering and interference effects while maintaining the underlying polymer layer's hydrophilic properties and water absorption capability intact, avoiding the need to apply additional porous oxide layers that would block water penetration.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent creates a surface nanostructure that copies the functional properties of complex multilayer antireflection systems but achieves the same effect through a single plasma-treated layer. The nanostructure on the polymer layer surface replicates the optical interference effects of traditional porous oxide layers without requiring separate material layers, thus preserving water absorption while achieving antireflection.

Inventive Principle:
Principle #26Copying

2Object-affected harmful factors

If traditional antireflection coatings are applied to reduce reflection, then transparency is improved, but undesired color impressions occur when light incidence is oblique

Engineering Contradiction:
ImprovereflectionVSAvoidcolor neutrality at oblique angles
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The patent changes the physical parameters of the surface by creating a nanostructure with specific pore sizes and distributions through plasma treatment. This nanostructure produces broadband antireflection effects that remain color-neutral across different viewing angles, unlike traditional thin-film interference coatings that exhibit strong angle-dependent color shifts. The nanostructure's multiple scattering paths and gradual refractive index transition maintain consistent optical appearance.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If additional layers are applied to the anti-fog polymer layer to achieve antireflection, then reflection is reduced, but the complexity of the coating system increases

Engineering Contradiction:
ImprovereflectionVSAvoidcoating system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the antireflection function with the existing anti-fog polymer layer by applying plasma treatment directly to its surface. This combines what would traditionally require separate antireflection and anti-fog layers into a single integrated coating system. The plasma-generated nanostructure provides antireflection while the underlying polymer maintains anti-fog properties, eliminating the need for additional porous oxide layers or complex multilayer interference systems.

Inventive Principle:
Principle #5Merging (Combining)

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 method produces an optical element with a neutral color effect, improved reflection reduction, and insignificantly impaired anti-fogging performance, even at oblique light angles, while maintaining mechanical stability and ease of cleaning, with enhanced transmission and resistance to external influences.

Implementation Method 1

a plasma etching process to produce a nanostructure on a surface of an anti-fog polymer layer by bombarding the anti-fog polymer layer surface with high-energy ions

Methodology Applied
Scientific EffectPlasma etching: Plasma

Implementation Method 2

bombarding the substrate surface with high-energy ions, which are generated using a plasma ion source

Methodology Applied
Scientific EffectIon bombardment: Ion Beam

Implementation Method 3

the reflection-reducing effect of which is based on optical interference

Methodology Applied
Scientific EffectOptical interference: Interference

Implementation Method 4

fog-reducing polymer layers contain highly hydrophilic polymers that can absorb water, so that when water condenses, fine water droplets are absorbed by the layer within a short time

Methodology Applied
Scientific EffectHydrophilic absorption: Absorption (physical)

Data Source

PatentEP2118691B1Method for producing an optical element having a reflection-reducing Anti-fog layer
Publication Date: 2016.11.16 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2118691B1 patent drawingFigure 1A~1C
  • EP2118691B1 patent drawingFigure 2~4
  • EP2118691B1 patent drawingFigure 5

AI summary

On an optical element (1), which is provided with a fogging-reducing polymer layer (2), a reflection-reducing nanostructure (7) is formed on the surface of the fogging-reducing polymer layer(2).