Ophthalmic Lens Rear-Face Multilayer Antireflective Coating for UV and NIR
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Solution Overview
Problem
Existing antireflective coatings for optical lenses struggle to provide low reflection in the NIR, UVA, UVB, and visible regions while maintaining a thin and economically feasible design, with existing multilayer stacks being too thick and ineffective against harmful blue light and UV radiation.
Innovation Solution
A multilayered antireflective coating comprising alternating layers of high and low refractive index materials, optimized to achieve a mean reflection factor below 8% in the NIR region and below 5% in the UVA-UVB range, with a thickness of 500 nm or less, while maintaining low reflection in the visible region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a multilayered antireflective coating is designed to reduce reflection in the visible region, then the mean light reflection factor in the visible region is reduced below 2.5%, but the coating becomes too thick and is ineffective against harmful blue light and UV radiation
Solution Approach 1:
The patent segments the antireflective coating into multiple thin layers with alternating high and low refractive indices. This segmentation allows the coating to achieve broadband antireflection across UV, visible, and NIR regions while maintaining a thin overall thickness. Each layer is optimized for specific wavelength ranges, with the high refractive index layers (TiO2, SiO2, Al2O3) and low refractive index layers (MgF2, SiO2) working together to create destructive interference for reflected light across multiple spectra.
Solution Approach 2:
The patent employs composite materials by combining multiple dielectric layers with different refractive indices (TiO2 with n≥2.0, SiO2 with n≥1.5, Al2O3 with n≥1.7, MgF2 with n≤1.4). This composite structure enables the coating to simultaneously address reflection reduction in visible, UV, and NIR regions, providing protection against harmful blue light and UV radiation while maintaining thin profile and aesthetic appearance.
2Object-affected harmful factors
If a multilayer stack is used to achieve low reflection in multiple regions, then reflection reduction is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent achieves multi-functionality by designing a single antireflective coating that simultaneously reduces reflection in UV (280-400 nm), visible (380-780 nm), and NIR (780-1400 nm) regions. The alternating high-low refractive index layer structure provides broadband antireflection properties, protecting against harmful blue light and UV radiation while maintaining aesthetic appearance. This universal coating eliminates the need for separate coatings for different spectral regions, simplifying the overall device structure.
Solution Approach 2:
The patent optimizes specific parameters including layer thicknesses (each layer between 10-200 nm), refractive index values (high index ≥1.55, low index <1.55), and the number of layers (at least 2 high-index and 2 low-index layers). By carefully controlling these parameters, the coating achieves low reflection across multiple spectral regions with a manageable thickness of 500 nm or less, balancing performance with manufacturing feasibility.
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 effectively reduces reflection across the NIR, UVA, UVB, and visible spectra, providing robust protection against harmful radiation without compromising manufacturing feasibility or aesthetics.
Implementation Method 1
An antireflection coating is usually a multilayer stack comprising interferential thin layers, generally an alternation of layers based on a dielectric material of high refractive index and a dielectric material of low refractive index
Implementation Method 2
a multilayered antireflective coating comprising a stack of at least two layers having a refractive index higher than or equal 1.55, defined as 'HI layer' and at least two layers having a refractive index lower than 1.55, defined as LI layer
Data Source
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AI summary
This invention relates to an ophthalmic lens comprising a substrate with a front main face and with a rear main face, said rear main face being coated with a multilayered antireflective coating comprising a stack of at least two layers having a refractive index higher than or equal 1.55, defined as "HI layer" and at least two layers having a refractive index lower than 1.55, defined as LI layer, characterized in that said multilayered antireflective coating is such that: - the mean reflection factor in the near infrared (NIR) region Rm NIR is lower than or equal to 8% at an angle of incidence of 35°, and10 - the mean reflection factor RUV (280 - 380 nm), weighted by the function W(λ) defined in the ISO 13666:1998 standard, is equal to or lower than 5% at an angle of incidence of 35°.