Diffractive Ophthalmic Lens Echelette Curvature for Light Scatter Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multifocal ophthalmic lenses experience light scatter and dysphotopsia due to non-viewing foci, which affect vision quality, especially as individuals age and develop presbyopia, with existing diffractive profiles directing significant light energy to unwanted foci.
Innovation Solution
The development of ophthalmic lenses with a diffractive profile characterized by a continuous function over echelettes, where the zeroth and first diffraction orders have changing diffraction efficiencies with radius, and the use of a displacement function combining continuous cosine and sine functions to optimize light energy distribution, reducing scatter and directing less energy to non-viewing orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional diffractive profile is used with sharp vertical steps between echelettes, then the lens provides strong diffractive power for multifocal vision, but it generates significant light scatter and dysphotopsia due to non-viewing foci
Solution Approach 1:
The patent applies curvature to the transition zones between echelettes, replacing sharp vertical steps with smooth curved transitions. This curvature modifies the diffraction pattern by reducing energy in non-viewing orders while maintaining viewing order efficiency, thereby reducing light scatter and dysphotopsia without sacrificing diffractive power
Solution Approach 2:
The patent changes the geometric parameters of the echelettes, specifically the step height and zone dimensions, to optimize the diffraction pattern. By carefully controlling these parameters, the lens achieves strong diffractive power for multifocal vision while minimizing harmful light scatter effects
2Power
If the step height of transition zones is increased to improve diffractive efficiency, then light distribution between viewing orders improves, but light scatter and dysphotopsia increase
Solution Approach 1:
The patent optimizes the step height parameter of transition zones to achieve the desired diffractive efficiency while controlling light scatter. By carefully selecting and varying this parameter across different zones, the lens balances viewing order efficiency with reduction of harmful scatter effects
3Ease of manufacture
If conventional diffractive echelettes with sharp corners are used, then manufacturing is simpler, but light scatter increases due to the sharp corners
Solution Approach 1:
The patent replaces sharp corners with curved transitions in the echelette design. This curvature reduces light scatter by eliminating the sharp geometric features that cause scattering, while the manufacturing process remains feasible through standard lens fabrication techniques
4Adaptability or versatility
If diffractive lenses are designed to provide strong diffractive power for presbyopia correction, then vision at multiple distances is improved, but non-viewing foci create unwanted visual phenomena
Solution Approach 1:
The patent applies different local qualities to different regions of the lens by varying the echelette parameters (step height, zone dimensions, curvature) across the optical zone. This allows optimization of diffractive power for presbyopia correction in the central region while controlling non-viewing order energy in peripheral regions to reduce dysphotopsia
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
This approach significantly reduces light scatter and improves vision quality by tailoring light energy distribution between viewing and non-viewing foci, mitigating dysphotopsia and enhancing the ability to focus on both near and far objects.
Implementation Method 1
Multifocal IOLs may, for example, often rely on a diffractive optical surface to direct portions of the light energy toward differing focal distances
Implementation Method 2
Like other lenses, diffractive monofocal or multifocal lenses can make use of a material having a given refractive index and a surface curvature to provide a refractive power
Data Source
AI summary
Ophthalmic lenses and methods for their design and use involve displacement functions based on the sum of a continuous cosine function and a continuous sine function, optionally over a plurality of echelettes. Exemplary monofocal and multifocal diffractive ophthalmic lenses provide reduced light scatter and/or improved light energy distribution properties. Such properties can be provided by diffractive profiles, often having subtlety shaped echelettes with appropriately curving profiles. Light scatter may be generated by the sharp corners associated with vertical steps between adjacent conventional diffractive echelettes. Smooth diffractive profiles of the invention reduce light scatter. Light energy directed toward non-viewing diffractive orders may have a unwanted effects on vision quality. Diffractive profiles as described herein may limit the light energy in certain, selected orders, thereby improving viewing quality and mitigating unwanted effects such as dysphotopsia. Diffractive profiles may also vary the light energy distributed between individual echelettes, providing additional advantages in various viewing situations.