Interference-Coated Optical Lens Marking With Selective Laser Ablation
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Solution Overview
Problem
Existing methods for marking ophthalmic lenses, such as ink and laser marking, face challenges with visibility to the wearer, lack of control over marking depth, and potential damage to coatings like anti-reflective layers.
Innovation Solution
A method using a laser beam with a specific wavelength to ablate the inner layer of a multi-layer interference coating, where the inner layer absorbs the marking wavelength more significantly than other layers, allowing controlled and localized marking that is visible to observers but not the wearer, with minimal impact on the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser beam marking is used on optical lenses, then marking visibility to external observers is improved, but control over marking depth deteriorates and coating damage occurs
Solution Approach 1:
The interference coating is divided into multiple layers with different optical properties. The marking process selectively targets specific layers (e.g., the high-index layer) while preserving others, enabling controlled depth modulation. This segmentation allows the marking depth to be precisely controlled by adjusting which layers are affected, resolving the contradiction between visibility and depth control.
Solution Approach 2:
Different layers of the interference coating are given different functional properties - some layers are designed to be more laser-absorbent than others. By selecting a wavelength that preferentially interacts with specific layers, the marking process achieves localized modification at controlled depths, improving both visibility and depth control simultaneously.
2Illumination intensity
If laser beam energy is increased to improve marking visibility, then marking depth increases, but coating integrity deteriorates due to excessive ablation
Solution Approach 1:
The laser wavelength is specifically selected to match the absorption characteristics of particular coating layers. By tuning the wavelength parameter, the process achieves effective marking at lower energy levels, avoiding excessive ablation and coating damage while maintaining sufficient visibility.
Solution Approach 2:
The interference coating layers themselves act as intermediaries that mediate the laser energy interaction. Certain layers absorb laser energy preferentially and convert it to controlled ablation, protecting underlying layers from damage. This intermediary mechanism enables visible marking without excessive coating degradation.
3Ease of manufacture
If ink marking is used on optical lenses, then marking application is simplified, but visibility to the wearer deteriorates and permanence is reduced
Solution Approach 1:
The mechanical ink application process is replaced with a laser-based optical field approach. The laser marking process directly modifies the coating material through photothermal or photomechanical effects, eliminating the need for ink application while achieving permanent, controlled markings that are invisible to the wearer but visible externally.
4Object-affected harmful factors
If multiple partial ablations are performed in the same pixel to avoid excessive engraving, then coating damage is reduced, but marking continuity deteriorates
Solution Approach 1:
The coating structure is segmented into multiple layers that can be selectively removed. By targeting specific layers for ablation rather than repeatedly ablating the same depth, the process achieves continuous-looking markings without excessive local damage, as each layer removal contributes to the overall marking pattern.
Solution Approach 2:
The laser marking process uses periodic pulsed delivery with carefully controlled timing and positioning. This periodic action allows heat dissipation between pulses and prevents excessive local heating while building up continuous markings through sequential pulse application, maintaining both coating integrity and marking continuity.
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
Achieves a visible and controlled marking pattern on ophthalmic lenses that maintains the integrity of the interference coating, ensuring the marking is not visible to the wearer while enhancing visibility to external observers.
Implementation Method 1
The inner layer absorbing the marking wavelength more significantly than any layer located between the electromagnetic source and the inner layer
Implementation Method 2
exposure of at least the inner layer at a given point called the marking point, by means of the laser beam at the marking wavelength, so as to ablate, at the marking point, the inner layer over at least part of its thickness
Implementation Method 3
so as to ablate, at the marking point, the inner layer over at least part of its thickness, and any layer located between the electromagnetic source and the inner layer
Implementation Method 4
the interference coating being such that it has a reflection coefficient Re in the visible range (380-780 nm)
Data Source
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AI summary
A method for marking an optical article (20) coated with an interference coating comprising at least two layers, an inner layer (15) and an outer layer (14), and having reflection coefficient Re; by exposure of the inner layer (15), at a marking point (P), by means 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. The invention also relates to an optical article coated with an interference coating having at least two layers, an inner layer and an outer layer, said article comprising a marking pattern formed by local absence of layers.