Curved Diffractive Ophthalmic Lens Profile Reduces Light Scatter
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Solution Overview
Problem
Current monofocal and multifocal diffractive ophthalmic lenses suffer from light scatter and dysphotopsia due to non-viewing diffractive orders, which affect vision quality, especially as people age and develop presbyopia or cataracts.
Innovation Solution
The development of ophthalmic lenses with a diffractive profile characterized by a continuous function over echelettes, optimizing light energy distribution by limiting energy to non-viewing diffractive orders and using smoothly curving profiles to reduce scatter, with a focus on directing more energy to viewing foci, thereby mitigating dysphotopsia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional diffractive profiles with stepped echelettes are used, then diffractive power is achieved for multifocal vision, but light scatter and dysphotopsia occur due to non-viewing diffractive orders
Solution Approach 1:
The patent applies curvature by replacing the conventional stepped echelette profile with a continuously curving diffractive profile. The surface features smooth curved transitions between zones rather than abrupt steps, which eliminates the sharp edges that cause light scatter while maintaining the diffractive optical path differences needed for multifocal vision. This curved profile directs light more precisely to viewing foci and reduces energy in non-viewing diffractive orders.
2Ease of manufacture
If sharp cornered echelette profiles are used, then manufacturing is simplified, but light scatter increases at the corners
Solution Approach 1:
The patent replaces sharp cornered echelette profiles with continuously curving profiles that have no abrupt discontinuities. The smooth curved surfaces eliminate the sharp corners that scatter light, while the curvature is designed to maintain the necessary optical path differences for diffractive functionality. This approach balances manufacturing feasibility with optical performance by using curves that can be fabricated with modern precision techniques while eliminating corner-induced scatter.
3Power
If more light energy is directed to non-viewing diffractive orders, then diffractive efficiency at viewing foci may improve, but unwanted visual phenomena like halos increase
Solution Approach 1:
The patent applies local quality by designing the diffractive profile to have different curvature characteristics at different locations and zones. The continuous curving profile is optimized locally to control the distribution of light energy, directing more energy to viewing foci while minimizing energy in non-viewing orders that cause halos. Each zone of the diffractive surface has a specifically tailored curvature to achieve the desired local light distribution, balancing efficiency with visual quality.
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 significantly reduces light scatter and improves vision quality by effectively managing light energy distribution, enhancing the ability to focus on both near and far objects without unwanted visual phenomena like halos and scatter.
Implementation Method 1
diffractive profile having a continuous function over a plurality of echelettes... The diffractive profile has, in the visible waveband, a zeroth diffractive order, a first diffractive order having a diffraction add power...
Implementation Method 2
The echelettes have smoothly curving profiles throughout the diffractive surface to inhibit step-induced scatter... significantly reduces light scatter and improves vision quality
Data Source
AI summary
The present invention provides improved ophthalmic lenses and methods for their design and use. Monofocal and multifocal diffractive ophthalmic lenses having reduced light scatter, improved light energy distribution properties, and/or other improvements in optical performance are provided. These properties are provided, at least in part, by the diffractive profiles of the invention, often having subtlety shaped echelettes with appropriately curving profiles. Smooth diffractive profiles may be used reduce light scatter. Diffractive profiles may be configured to limit the light energy in certain selected orders, thereby improving viewing quality and mitigating unwanted effects such as dysphotopsia. Diffractive profiles of may additionally or alternatively vary the light energy distributed between individual echelettes, providing additional advantages in various viewing situations.