Sputtered Antireflective Coating Stack for Ophthalmic Lenses
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Solution Overview
Problem
Existing ophthalmic lenses with antireflective coatings on their rear side face challenges in maintaining effective UV protection and thermomechanical performance, particularly at high temperatures, while also ensuring robustness and resistance to abrasion and scratches.
Innovation Solution
A multilayered antireflective coating stack deposited by sputtering, comprising layers with varying refractive indices, is applied to the rear side of ophthalmic lenses, enhancing UV protection and thermomechanical properties, and improving resistance to scratches and abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional antireflective coating is applied to reduce UV reflection, then UV protection is improved, but thermomechanical performance and critical temperature deteriorate
Solution Approach 1:
The patent divides the single-layer antireflective coating into a multilayer stack with alternating high and low refractive index layers. This segmentation allows each layer to contribute differently to the overall performance, achieving reduced UV reflection while maintaining thermomechanical stability through the distributed structure.
Solution Approach 2:
The patent uses composite material structure by combining materials with different refractive indices (high index layers and low index layers) in a multilayer configuration. This composite approach enables simultaneous optimization of optical properties (UV reflection reduction) and thermomechanical properties (critical temperature maintenance).
2Reliability
If the coating deposition protocol is modified to improve AR properties, then optical performance is improved, but robustness to deposition variations deteriorates
Solution Approach 1:
The patent systematically varies deposition parameters such as substrate temperature, deposition rate, and layer thickness to identify optimal ranges that provide both desired AR properties and robustness. By establishing specific parameter ranges rather than fixed values, the coating becomes less sensitive to minor deposition protocol variations.
3Temperature
If existing techniques are used to improve critical temperature, then thermomechanical performance is improved, but material choice and layer thickness flexibility are reduced
Solution Approach 1:
By segmenting the coating into multiple layers with different functions, the patent allows independent optimization of each layer's material composition and thickness. This enables selection from a broader range of materials for different layers without compromising overall critical temperature performance.
Solution Approach 2:
The multilayer composite structure allows combination of different materials (oxides, nitrides, fluorides) in specific configurations, providing versatility in material choice while the overall composite structure maintains high critical temperature through synergistic interactions between layers.
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 sputtered antireflective coating stack achieves reduced UV and visible light reflection, increased critical temperature, and improved durability, providing enhanced protection and performance in sunwear applications.
Implementation Method 1
A multilayered antireflective coating stack deposited by sputtering, comprising layers with varying refractive indices, is applied to the rear side of ophthalmic lenses
Implementation Method 2
The multilayered antireflective coating of the invention comprises a stack of at least one layer A having a refractive index nA lower than or equal to 1.55, and of at least one layer B having a refractive index nB higher than 1.55, with a mean light reflection factor of the rear face in the visible region Rv lower than 2%, and a mean reflection factor in the range 280 nm to 380 nm Ruv of the rear face lower than 5%
Data Source
Figure 1
AI summary
The present invention provides a UV antireflective coating stack for ophthalmic lenses. The antireflective coating stack is deposited by sputtering, which lowers the reflectivity of the antireflective stack in the UV range and maintains low reflectivity in the visible range. The antireflective coating stack offers improved thermo-mechanical performance as compared to evaporation-based UV antireflective stacks.