Diffractive Intraocular Lens Step Heights for Chromatic Aberration Control
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Solution Overview
Problem
Conventional intraocular lenses suffer from longitudinal chromatic aberration and limited depth of focus, affecting vision quality due to different colors of light being focused at different distances from the lens.
Innovation Solution
A method for fabricating intraocular lenses with individually optimized zones and phase folding of echelettes, where each zone has a unique step height and phase difference, enhancing depth of focus and reducing chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional IOLs use single focal length design, then manufacturing is simple, but depth of focus is limited
Solution Approach 1:
The lens is divided into multiple zones (first zone, second zone, third zone) with different focal lengths. Each zone is further segmented into multiple echelettes with different step heights, allowing independent optimization of each segment's optical properties to achieve extended depth of focus while maintaining manufacturability through modular design
Solution Approach 2:
Different zones of the lens are assigned different focal lengths and optical properties. The first zone provides distance focus, the second zone provides intermediate focus, and the third zone provides near focus. Each zone's echelettes have specifically optimized step heights tailored to their local optical requirements, creating local quality variations that extend the overall depth of focus
2Ease of manufacture
If conventional IOLs use standard diffractive structures, then manufacturing is straightforward, but chromatic aberration occurs
Solution Approach 1:
Different zones have different step height configurations optimized for their specific focal lengths. The first zone echelettes have step heights optimized for distance focus, the second zone echelettes for intermediate focus, and the third zone echelettes for near focus. This local optimization reduces chromatic aberration by ensuring each zone's diffractive structure is tailored to its specific optical function
Solution Approach 2:
The step heights of echelettes are varied across different zones to optimize optical performance. By changing the step height parameter locally in each zone, the patent achieves reduced chromatic aberration while maintaining manufacturability through a systematic parameter variation approach rather than completely novel structures
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 method improves the depth of focus and reduces chromatic aberration, providing a more achromatic and extended depth of focus for intraocular lenses.
Implementation Method 1
The IOL may have a diffractive structure with multiple zones. Each zone may have different step heights. The diffractive structure may be used to provide a first focal length, a second focal length, and a third focal length.
Data Source
Figure 1A~1B
Figure 2~3B
Figure 4~5B
AI summary
A method and system provide an ophthalmic device. The ophthalmic device includes an ophthalmic lens having anterior surface, a posterior surface and at least one diffractive structure including a plurality of zones. The at least one diffractive structure is for at least one of the anterior surface and the posterior surface. Each zone includes at least one echelette having a least one step height. The step height(s) are individually optimized for each zone. To compensate chromatic aberration of eye from distance to a range of vision, a greater than 2π phase step height may be employed and the step height(s) folded by a phase, which is an integer multiple of two multiplied by π. Hence chromatic aberration of eye may be compensated to improve vision from distance to near.