Optical Lens Interferential Coating for UV and Abrasion Control
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Solution Overview
Problem
Existing optical articles, such as ophthalmic lenses, face challenges in achieving improved abrasion resistance and thermal resistance while maintaining good adhesion to the substrate and preserving optical properties, particularly in the UV and visible wavelength ranges.
Innovation Solution
A multilayer interferential coating is applied to the optical substrate, comprising at least 7 layers with specific refractive index and thickness ratios, including a monolayer sub-layer and a stack of high and low refractive index layers, with the outermost high refractive index layer being less than 40 nm thick, to enhance mechanical and thermal performance without compromising optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of high refractive index layers in the interferential coating is increased to improve UV reflection, then UV protection is enhanced, but abrasion resistance deteriorates
Solution Approach 1:
The patent changes the thickness parameter of the outermost high refractive index layer to less than 40 nm, which is thinner than conventional layers. This parameter change reduces UV reflection slightly but dramatically improves abrasion resistance and adhesion, resolving the contradiction between UV protection and mechanical durability
Solution Approach 2:
The patent uses a composite multilayer structure combining multiple high refractive index materials (TiO2, ZrO2, Ta2O5) and low refractive index materials (SiO2, MgF2) in specific sequences. This composite approach allows optimization of both optical properties (UV reflection) and mechanical properties (abrasion resistance) through material selection and layer configuration
2Reliability
If ion assistance is used during deposition to improve adhesion and reduce porosity, then coating density and adhesion are enhanced, but compressive stress increases leading to delamination
Solution Approach 1:
The patent modifies deposition parameters by using ion assistance at reduced ion flux and lower deposition rates. This parameter change allows achieving good adhesion and dense coating structure without generating excessive compressive stress that would cause delamination
Solution Approach 2:
The patent applies ion assistance partially rather than excessively - using it to achieve sufficient adhesion and density without over-ionizing the coating. This partial application avoids the harmful side effect of excessive compressive stress while maintaining the beneficial effects of improved adhesion
3Illumination intensity
If the total thickness of the anti-reflection coating is increased to improve optical properties, then antireflection performance is enhanced, but thermal resistance deteriorates
Solution Approach 1:
The patent changes the thickness distribution parameter by making the outermost high refractive index layer very thin (<40 nm) while optimizing other layer thicknesses. This creates a thinner overall coating that maintains antireflection performance through optimized refractive index matching while improving thermal resistance by reducing the total thermal barrier
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 solution provides enhanced abrasion resistance, good adhesion, and resistance to heat and temperature variations, maintaining low UV reflection and improving optical properties in the visible range, while being compatible with standard manufacturing processes.
Implementation Method 1
a multilayer interferential coating is applied to the optical substrate, comprising at least 7 layers with specific refractive index and thickness ratios
Implementation Method 2
a multilayer transparent interferential coating, typically an antireflection coating
Data Source
AI summary
The invention relates to an optical lens comprising a substrate having a front main face and a rear main face, said rear main face of which being successively coated with: - (A) a first high refractive index sheet having a refractive index higher than 1.55, which does not comprise any TaaOs layer, - (B) a second low refractive index sheet having a refractive index of 1.55 or less in direct contact with the former sheet, - (C) a third high refractive index sheet having a refractive index higher than 1.55 in direct contact with the former sheet, - a monolayer sub-layer having a thickness higher than or equal to 100 nm in direct contact with the former sheet (C), - a multilayer interferential coating comprising a stack of at least 6 layers with at least one high refractive index layer and at least one low refractive index layer, wherein the outermost high refractive index layer of the multilayer interferential coating has a thickness lower than 40 nm, and the mean reflection factor Ruv on said rear main face between 280 nm and 380 nm, weighted by the function W(λ) defined in the ISO 13666:1998 standard, is lower than 10 %, for an angle of incidence of 35°.