Interference-Coated Optical Lens Marking by Selective Inner-Layer Ablation
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Solution Overview
Problem
Existing methods for marking ophthalmic lenses, such as ink marking and laser ablation, face challenges including compatibility with lens surfaces, visibility to the wearer, and lack of control over marking depth, leading to potential damage to coatings like antireflection or anti-scratch coatings.
Innovation Solution
A method using a marking machine with a laser beam that selectively ablates the interior layer of an interference coating, differing in reflection coefficient, allowing for controlled and continuous marking patterns without damaging the surrounding layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser ablation is used to create visible markings on ophthalmic lenses, then the marking visibility to exterior observers is improved, but the marking depth control deteriorates leading to potential damage to coatings
Solution Approach 1:
The interference coating is segmented into multiple layers with different optical properties. The interior layer has high absorption at the laser wavelength and is selectively removed, while the exterior layer with different optical properties remains intact. This segmentation allows controlled ablation that creates visible markings without damaging the entire coating stack.
Solution Approach 2:
The marking process applies local quality changes by selectively ablating only the interior layer in specific regions. The exterior layer maintains its original properties in marked and unmarked areas, while the interior layer is locally removed to create the visible effect. This localized modification achieves visibility without compromising overall coating integrity.
2Reliability
If successive multiple partial ablations are performed in a given pixel to avoid over-engraving, then the coating damage is reduced, but the marking continuity deteriorates producing non-contiguous spots
Solution Approach 1:
The interior layer is preliminarily designed to have high absorption at the laser wavelength, making it selectively vulnerable to ablation. This preliminary property assignment allows the laser to remove the interior layer in a single pass or few passes without needing multiple successive partial ablations, thereby maintaining marking continuity while protecting the exterior layer.
Solution Approach 2:
The optical parameters of the interior layer are specifically changed to have high absorption at the laser wavelength, creating a selective ablation condition. This parameter change allows controlled removal of the interior layer with precise depth control, achieving both coating protection and continuous marking without the need for multiple partial passes.
3Illumination intensity
If the laser beam is applied with high energy to ensure visible marking, then the marking visibility is improved, but the risk of attacking and damaging the coating increases
Solution Approach 1:
The interior layer is designed with local quality of high absorption at the laser wavelength, concentrating the laser energy effect specifically in this layer. This allows using sufficient laser energy to create visible markings while the energy is locally confined to the interior layer, preventing damage to the exterior layer and substrate.
Solution Approach 2:
The high absorption property of the interior layer at the laser wavelength, which could be seen as a vulnerability, is converted into a benefit. This selective absorption allows the laser energy to be harmfully concentrated in the interior layer for effective marking, while the exterior layer remains protected. The potential harm is directed precisely where needed without affecting other components.
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 method enables precise and visible marking on ophthalmic lenses that is not perceivable to the wearer, maintaining the integrity of the existing coatings and ensuring high transmittance and reflection properties.
Implementation Method 1
irradiating at least the interior layer in a given spot called the marking spot, by means of the laser beam at the marking wavelength, so as to ablate, in the marking spot, the interior layer
Implementation Method 2
the interior layer absorbing the marking wavelength more greatly than any layer located between the electromagnetic source and the interior layer
Implementation Method 3
the interference coating being such that it has a reflection coefficient Re in the visible domain (380-780 nm)... the ablated zone having a reflection coefficient Rm in the visible domain (380-780 nm), Rm being different from Re
Data Source
AI summary
Disclosed is a method for marking an optical article coated with an interference coating including at least two layers, an inner layer and an outer layer, and having reflection coefficient Re; by exposure of the inner layer, at a marking point, by way of a laser beam at a marking wavelength, in such a way as to ablate the inner layer and any layer further away from the substrate; the ablated area having a reflection coefficient Rm different from Re by at least 1%; the inner layer absorbing the marking wavelength to a greater degree than any layer further away from the substrate. Also disclosed is an optical article coated with an interference coating having at least two layers, an inner layer and an outer layer, the article including a marking pattern formed by local absence of layers.