In-Mould Coating for High Index Optical Elements
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Solution Overview
Problem
The formation of interference patterns when low index hard coats are applied to high index optical elements, such as ophthalmic lenses, due to refractive index mismatch between the hard coat material and the plastic substrate, complicates the manufacturing process and increases costs with the use of index matched coatings.
Innovation Solution
An in-mould coating process involving controlled mixing of conventional hard coat materials with high index lens materials at the interface before curing, using a UV-curable hard coat monomer composition, such as (meth)acrylate or epoxy monomers, to form a partially cured hard coat layer that intermixes with the high index optical element precursor, creating a diffuse interface that minimizes interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If low index hard coats are applied to high index optical elements, then abrasion resistance is improved, but interference patterns form due to refractive index mismatch
Solution Approach 1:
The patent changes the refractive index parameter of the hard coat material to match the high index optical element substrate. Instead of using conventional low index hard coat materials, the invention employs specially formulated hard coat materials with refractive indices matched to high index plastics, thereby eliminating interference patterns while maintaining abrasion resistance improvements
Solution Approach 2:
The patent uses composite hard coat materials that combine the desired abrasion resistance properties with matched refractive index characteristics. These composite materials are specifically designed to have both the mechanical durability of hard coats and the optical compatibility required for high index elements, resolving the contradiction between protection and optical quality
2Object-affected harmful factors
If index matched coatings are used to avoid interference patterns, then optical quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the hard coat application process with the optical element manufacturing process into a single integrated operation. By applying the index-matched hard coat material during the same manufacturing cycle as the optical element formation, the invention eliminates separate coating steps, reduces manufacturing complexity, and maintains optical quality without additional process stages
Solution Approach 2:
The patent employs a simplified manufacturing approach that uses readily available high index plastic materials and standard coating equipment, avoiding the need for specialized expensive index-matched materials or complex multi-step processes. The solution uses economical materials and methods that achieve the desired optical quality without increasing manufacturing cost or 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
This method allows for the formation of high index optical elements with hard coats that exhibit minimal interference patterns without increasing manufacturing complexity, resulting in lenses with commercially acceptable abrasion resistance and outdoor weather durability.
Implementation Method 1
irradiating the hard coat monomer layer with UV radiation under conditions to form a partially cured hard coat layer
Implementation Method 2
controlled mixing of conventional hard coat materials and high index lens materials at the interface between the hard coat and the bulk lens material prior to lens curing allows for the formation of a hard coated high index lens without interference patterns
Data Source
AI summary
Disclosed is a method of forming a coated optical element. The method includes providing a mould assembly having opposed mould sections and applying a UV-curable hard coat monomer composition to the casting face of at least one of the mould sections to form a hard coat monomer layer. The hard coat layer is irradiated with UV radiation under conditions to form a partially cured hard coat layer. The assembled mould is filled with a high index optical element precursor material the optical element precursor material and the partially cured hard coat layer are cured to form a high index optical element having a hard coat.