Ophthalmic Lens Fresnel Layer for Frame Fitting
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Solution Overview
Problem
Existing ophthalmic lenses with high curvature and strong prescriptions face challenges in fitting into frames due to excessive edge thickness, leading to discomfort and aesthetic issues, as previous solutions fail to simultaneously address optical performance and thickness.
Innovation Solution
A method involving a Fresnel layer superposed on a carrier with a constrained curvature profile on one face of the lens, compensating for geometric effects, allowing for easier mounting in frames while maintaining optical correction, by defining specific profiles of curvature and machining the back face as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the curvature of the lens face is increased to facilitate fitting in a spectacle frame, then the ease of fitting is improved, but the edge thickness increases leading to discomfort and aesthetic issues
Solution Approach 1:
The lens face is segmented into a carrier surface and a superposed Fresnel layer. The carrier provides the base curvature for frame fitting, while the Fresnel layer adds optical power without increasing edge thickness. This segmentation allows independent optimization of fitting characteristics and optical correction.
Solution Approach 2:
The optical power is transferred from the traditional continuous curved surface to a Fresnel layer with concentric rings. This dimensional transformation allows the lens to achieve high optical power in the central region while maintaining a flatter peripheral profile, reducing edge thickness and improving aesthetics.
2Reliability
If the prescription power is increased to correct strong vision defects, then the optical correction is improved, but the lens thickness increases leading to weight and aesthetic problems
Solution Approach 1:
The lens is divided into a carrier providing structural support and a Fresnel layer providing optical correction. This allows high prescription power to be achieved through the Fresnel layer's concentric ring structure without proportionally increasing overall lens thickness and weight.
Solution Approach 2:
The Fresnel layer changes the optical path by introducing discrete step-like surfaces that redirect light. This parameter change in surface geometry allows high optical power to be achieved with minimal material thickness, reducing weight while maintaining correction effectiveness.
3Area of stationary object
If a high curvature profile is used to reduce lens diameter, then the compactness is improved, but the peripheral zone quality deteriorates with optical defects
Solution Approach 1:
The lens applies different optical characteristics to different zones: the carrier provides a base curvature for overall shape and frame fitting, while the superposed Fresnel layer provides precise optical correction in the optical useful zone. This local differentiation maintains high optical quality in the peripheral zone while achieving compact dimensions.
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 reduces lens thickness and weight, enhances fitting ease, and maintains optical continuity, providing improved aesthetic appeal and wearer comfort with a larger field of view and reduced peripheral thickness.
Implementation Method 1
a Fresnel layer, the first zone and the peripheral zone being centered on said geometric center
Data Source
AI summary
Method for defining one face of an ophthalmic lens, having a surface formed by superposing a Fresnel layer and a continuous surface referred to as the “carrier”. Also disclosed is an ophthalmic lens comprising such a face. The method allows a Fresnel layer to be defined that compensates for geometric effects induced by a variation in the curvature of the carrier on the light incident on the face of an ophthalmic lens. This method is particularly useful when the curvature of the face of the ophthalmic lens is adapted to facilitate fitting it into a spectacle frame.