Multilayer Antireflective Coating for High NIR and Blue Light Reflection
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Solution Overview
Problem
Current antireflective coatings for ophthalmic lenses fail to achieve high reflection in the near-infrared (NIR) and blue light regions while maintaining low reflection in the visible region, often resulting in coatings that are too thick, mechanically stressed, and economically impractical.
Innovation Solution
A multilayer antireflective coating with alternating high and low refractive index layers, where the total physical thickness is ≤600 nm, achieving a mean reflection factor ≥20% in the NIR region and ≥7% in the blue light region, while maintaining a reflection factor ≤2.5% in the visible region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional antireflective coatings are designed to reduce reflection in the visible region, then reflection in the visible region is reduced, but reflection in the NIR and blue light regions is not sufficiently limited
Solution Approach 1:
The antireflective coating is designed to perform multiple functions simultaneously: reducing reflection in the visible region (380-780 nm) while also limiting transmission of harmful NIR radiation (780-1400 nm) and blue light (420-450 nm). This multi-functionality is achieved through a specific multilayer structure with alternating high and low refractive index layers, where each layer contributes to different spectral regions, allowing a single coating to address multiple harmful radiations without requiring separate coatings for each wavelength range.
Solution Approach 2:
The coating employs composite material structure with alternating layers of high refractive index material (n ≥ 2.0) and low refractive index material (n < 1.6). This composite approach allows precise control over the optical properties across different spectral regions. The high refractive index layers provide strong reflection for NIR and blue light, while the low refractive index layers contribute to antireflective performance in the visible region, creating a synergistic effect that achieves multiple objectives simultaneously.
2Object-affected harmful factors
If multilayer coatings are used to achieve high reflection in NIR region, then reflection in NIR region is improved, but the coating thickness increases and mechanical stress increases
Solution Approach 1:
The invention achieves high NIR reflection with reduced thickness by precisely controlling the optical thickness (physical thickness × refractive index) of each layer. The total physical thickness is constrained to ≤600 nm through optimized layer thicknesses. The alternating high and low refractive index materials create constructive interference for NIR wavelengths, enhancing reflection without requiring excessive thickness. This parameter optimization allows the coating to achieve ≥20% mean reflection factor in NIR region while maintaining thin overall dimensions.
Solution Approach 2:
Different layers of the coating are assigned different local properties: high refractive index layers (n ≥ 2.0) are positioned to provide strong reflection for NIR and blue light, while low refractive index layers (n < 1.6) are positioned to minimize visible region reflection. This spatial differentiation of optical properties within the multilayer structure enables each layer to contribute specifically to its target spectral region, achieving high NIR reflection without uniformly increasing overall coating thickness.
3Object-affected harmful factors
If multilayer coatings are used to achieve high reflection in NIR region, then reflection in NIR region is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The invention simplifies manufacturing by constraining the total physical thickness to ≤600 nm and limiting the number of alternating layers to 4-10 layers. These parameter constraints make the coating process more controllable and economically viable. The use of standard optical materials with well-known deposition characteristics further facilitates manufacturing. The optimized layer count and thickness ranges enable conventional vacuum deposition techniques to achieve the desired performance without requiring complex or expensive specialized processes.
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 provides a robust, aesthetically pleasing solution with high reflection in harmful blue light and NIR regions while ensuring low reflection in the visible region, enhancing protection and visibility without compromising manufacturing feasibility.
Implementation Method 1
A multilayer antireflective coating with alternating high and low refractive index layers, where the total physical thickness is ≤600 nm, achieving a mean reflection factor ≥20% in the NIR region and ≥7% in the blue light region, while maintaining a reflection factor ≤2.5% in the visible region.
Implementation Method 2
A multilayer antireflective coating with alternating high and low refractive index layers
Implementation Method 3
achieving a mean reflection factor ≥20% in the NIR region and ≥7% in the blue light region, while maintaining a reflection factor ≤2.5% in the visible region
Data Source
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AI summary
This invention relates to an optical article comprising a transparent substrate coated with an antireflective coating comprising at least two layers having a low refractive index, and at least two layers having a high refractive index, one layer having a high refractive index being the nearest from said substrate, characterized in that the total physical thickness of said antireflective coating is equal to or lower than 600 nm, and such that: - the mean reflection factor in the near infrared region is higher than or equal to 20 % at an angle of incidence lower than 35°, and - the mean reflection factor Rm B of blue light at a wavelength ranging from 420 to 450 nm is higher than or equal to 7.0 % at an angle of incidence lower than 15°.