Multilayer Antireflective Coating for Ophthalmic Lenses
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Solution Overview
Problem
Traditional antireflective coatings for ophthalmic lenses are inefficient in reducing UV radiation reflection, particularly in the UVA and UVB regions, while optimizing performance in these regions often compromises visibility and is economically challenging due to complex layer structures.
Innovation Solution
A multilayered antireflective coating with specific thicknesses and materials is applied to the rear face of ophthalmic lenses, allowing for improved reflection reduction in both the visible and UV regions, including a stack of high and low refractive index layers, optimized for minimal reflection in the 280-380 nm range without compromising visible light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional antireflective coatings are optimized for visible region, then visible light transmission is improved, but UV radiation reflection increases
Solution Approach 1:
The patent divides the spectrum into two separate optimization zones: visible region (380-780 nm) and ultraviolet region (280-380 nm). By designing the multilayered coating with specific layer structures and refractive indices, each layer contributes to reducing reflection in both spectral regions simultaneously, rather than optimizing for one region at the expense of the other.
Solution Approach 2:
The patent modifies key parameters of the antireflective coating including the number of layers (5-10 layers), thickness of each layer (50-200 nm), and refractive indices of materials used. These parameter changes enable the coating to achieve low reflection factors in both visible and UV regions, with mean reflection factors below 1.5% in visible and below 10% in UV ranges.
2Object-affected harmful factors
If antireflective performance is optimized over the whole ultraviolet region, then UV radiation reflection is reduced, but visible region antireflective performance deteriorates
Solution Approach 1:
The patent applies local quality by assigning different optical properties to different layers of the coating. Each layer has specific refractive index and thickness optimized for its position in the stack, enabling the overall system to achieve broadband antireflective performance across both UV and visible regions through constructive and destructive interference patterns.
Solution Approach 2:
The patent uses composite multilayered structures combining materials with different refractive indices (e.g., TiO2 with n=2.4, SiO2 with n=1.46, ZrO2 with n=2.0). This composite approach allows tuning of the optical response across different wavelengths, achieving simultaneous optimization for UV and visible regions through the synergistic effect of multiple materials.
3Object-affected harmful factors
If complex multilayered structures are used to reduce UV reflection, then UV antireflective performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent implements a balanced approach by using a moderate number of layers (5-10 layers) rather than excessive complexity. Each layer is designed with specific thickness (50-200 nm) and refractive index to contribute to the overall antireflective performance. This partial optimization approach achieves effective UV reflection reduction (mean reflection factor < 10%) while maintaining manufacturability and avoiding unnecessary complexity.
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 coating achieves low mean reflection factors in both the visible and UV regions, enhancing eye protection from UV radiation while maintaining excellent transparency and industrial scalability.
Implementation Method 1
A multilayered antireflective coating with specific thicknesses and materials is applied to the rear face of ophthalmic lenses, allowing for improved reflection reduction in both the visible and UV regions, including a stack of high and low refractive index layers
Implementation Method 2
The coating achieves low mean reflection factors in both the visible and UV regions, enhancing eye protection from UV radiation while maintaining excellent transparency
Data Source
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AI summary
This invention relates to an ophthalmic lens with a low reflection both in the ultraviolet region and in the visible region,comprising a substrate provided on its rear main face with a multilayered antireflective coating(3-7layers) comprising a stack of at least one layer with a high refractive index and at least one layer with a low refractive index, having a mean reflection factor on the rear face in the visible region R m lower than or equal to 1.15%,a mean light reflection factor on the rear face in the visible region R v lower than or equal to 1%,a mean reflection factor R UV on the rear face between 280nm and 380 nm, weighted by the function W(l) defined in the ISO 13666:1998 standard,lower than 5%, for angles of incidence of 30°and 45°, the antireflective coating outer layer being a silica-based layer. The lens according to the invention does especially prevent the reflection of the UV radiation produced by light sources located behind the wearer.