Multifocal Lens Diffractive Region Radial Efficiency Gradient
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Solution Overview
Problem
Diffractive optical power regions in lenses suffer from significant chromatic aberration and cosmetic issues, such as sharp delineations, which compromise vision and aesthetics, especially in multifocal lenses where the periphery exhibits the highest degree of chromatic aberration and is cosmetically unattractive.
Innovation Solution
A diffractive optical power region with a blended diffractive efficiency near the peripheral edge, where the diffraction efficiency decreases radially towards the edge, and the diffractive structures form a sawtooth pattern with varying heights to minimize chromatic aberration and create a lineless boundary, potentially using electro-active materials and individually addressable electrodes to control optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a diffractive optical power region is used to provide additional optical power for near distance correction, then the optical power for near vision is improved, but chromatic aberration increases significantly at the periphery
Solution Approach 1:
The patent applies local quality by making the diffractive efficiency vary radially across the lens. The central region maintains high diffractive efficiency for strong near vision correction, while the peripheral region gradually transitions to low or zero diffractive efficiency. This radial gradient in diffractive efficiency localizes the harmful chromatic aberration to the periphery where it is least visually impactful, while preserving the beneficial optical power in the central viewing zone.
2Power
If a diffractive optical power region with sharp boundary is used, then the optical power transition is clear, but the cosmetic appearance becomes unattractive with visible lines
Solution Approach 1:
The patent implements local quality by creating a radial gradient in diffractive efficiency that is strongest at the center and tapers to zero at the periphery. This continuous variation eliminates abrupt boundaries and sharp delineations, producing a lineless appearance that is cosmetically appealing while maintaining clear optical power transition through the gradual blending of diffractive and refractive zones.
Solution Approach 2:
The patent merges the diffractive optical power region with the refractive lens substrate by blending the diffractive efficiency to zero at the periphery. This merging eliminates the sharp boundary between the diffractive region and the rest of the lens, creating a seamless transition that is both optically functional and cosmetically attractive.
3Ease of manufacture
If the diffractive structures have constant height, then the manufacturing is simple, but the chromatic aberration is maximized at the periphery
Solution Approach 1:
The patent applies parameter changes by varying the height of the diffractive structures radially across the lens. The central structures have greater height for strong diffraction and optical power, while the peripheral structures progressively reduce in height, blending to zero at the edge. This radial variation in structure height reduces chromatic aberration at the periphery while maintaining manufacturing feasibility through standard lens fabrication techniques.
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 chromatic aberration and enhances the cosmetic appeal of multifocal lenses by blending the diffractive efficiency to zero at the peripheral edge, providing a smooth transition and minimizing visible lines, thus improving vision quality and wearer acceptance.
Implementation Method 1
A diffractive optical power region is a region of a lens or optic that generates optical power by diffracting light
Implementation Method 2
When the controller applies voltages to the plurality of individually addressable electrodes, the refractive index of electro-active material is altered to provide an optical power
Data Source
AI summary
A lens system is presented having a diffractive optical power region. The diffractive optical power region has a plurality of concentric surface relief diffractive structures. A greater portion of light incident on a diffractive structure near the center point contributes to the optical power than light incident on a diffractive structure peripherally spaced therefrom.