Optical Element Coating for Mark Visibility Control
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Solution Overview
Problem
Existing methods for creating marks on optical elements, such as ophthalmic lenses, often result in marks that are undesirably observable during normal use, causing optical distortions and affecting the wearer's experience.
Innovation Solution
A method involving a first coating layer with a specific refractive index difference applied over a mark on an optical substrate, where the difference is controlled between 0.02 and 0.24, and additional coating layers with a refractive index close to the substrate's, allowing the mark to be observable only under controlled conditions, such as electromagnetic energy exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a mark is introduced into an optical element using conventional methods (engraving, chemical leeching, laser), then the mark can be made observable under certain conditions, but the mark becomes undesirably observable during normal use causing optical distortion
Solution Approach 1:
The patent applies a coating layer with a specific refractive index (different from the substrate by 0.02 to 0.24) to change the optical parameters of the mark area. This refractive index difference causes light to refract differently at the mark location, making the mark observable without requiring physical engraving or chemical modification of the substrate. The coating can be removed or modified to reveal the mark when needed, while during normal use the coating maintains optical clarity.
Solution Approach 2:
The patent uses a composite structure consisting of the optical substrate and a coating layer applied over it. The coating layer acts as a protective and optical modification layer that can be designed with specific refractive index properties. This composite approach allows the mark to be embedded in the substrate while the coating controls its visibility and minimizes optical distortion during normal use.
2Loss of information
If the refractive index difference between coating layer and substrate is increased to enhance mark visibility, then the mark becomes more observable, but optical distortion and unwanted reflections increase
Solution Approach 1:
The patent specifies a controlled refractive index difference range (0.02 to 0.24) between the coating layer and substrate. This parameter optimization ensures sufficient refraction to make the mark observable while staying within limits that prevent excessive reflections and optical distortion. The refractive index of the coating is carefully selected to balance visibility enhancement with optical quality maintenance.
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 ensures that marks are substantially unobservable during normal use but can be made visible when needed, enhancing the visibility of information on optical elements without causing optical distortions.
Implementation Method 1
The first coating layer may have a first refractive index, and the optical substrate may have a second refractive index. A difference between the first refractive index and the second refractive index may have an absolute value of 0.02 to 0.24
Data Source
AI summary
The present invention relates to an optical element that includes a mark (18). The optical element has a first coating layer (22) over at least a portion of a surface of an optical substrate (20) having the mark (18) on the surface of the optical substrate, and one or more additional coating layers (24) over at least a portion of the first coating layer (22). The first coating layer has a first refractive index, and the optical substrate and the mark may have a second refractive index. A difference between the first refractive index and the second refractive index has an absolute value of 0.02 to 0.24. At least one of the first coating layer (22) and the one or more additional coating layers (24) may be applied by a controlled deposition of a coating material in droplet form.