Diffractive Eye Lens with Sub-Zone Geometry for Halo Reduction
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Solution Overview
Problem
Multifocal diffractive eye lenses with phase shifts greater than one wavelength produce significant 'halo-like' stray light, leading to visual impairment and reduced contrast sensitivity due to longitudinal chromatic aberrations, especially in distance vision.
Innovation Solution
A diffractive eye lens design with a significant diffraction efficiency for optical path length differences between principal sub-zones of more than one wavelength, where the principal sub-zones make up at least 94% of the diffraction zones, reducing the secondary halo and improving visual properties by minimizing negative orders of diffraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multifocal diffractive eye lenses use phase shifts greater than one wavelength to correct longitudinal chromatic aberrations, then chromatic aberration correction is improved, but significant halo-like stray light is produced leading to visual impairment and reduced contrast sensitivity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the optical path length difference between diffraction zones to achieve specific phase shifts (greater than one wavelength) that correct chromatic aberrations while minimizing harmful stray light. The diffraction zone geometry and optical path differences are optimized to balance chromatic correction with halo reduction.
Solution Approach 2:
The patent implements local quality by creating different optical path length differences in different regions of the lens. The diffraction zones are designed with specific local phase characteristics that correct chromatic aberrations in the optical path while maintaining overall lens performance and minimizing stray light generation.
2Adaptability or versatility
If diffractive structures are used to produce multiple principal refractive powers for multifocal vision, then vision quality at multiple distances is improved, but longitudinal chromatic aberration is amplified particularly in the smallest principal power for distance vision
Solution Approach 1:
The patent applies universality by designing a diffractive lens structure that simultaneously provides multiple functions: it creates multiple principal refractive powers for different viewing distances while also correcting longitudinal chromatic aberrations. The diffraction zones are configured to achieve this multi-functionality through carefully controlled optical path length differences.
Solution Approach 2:
The patent uses parameter changes by adjusting the optical path length differences between diffraction zones to achieve specific phase shifts that correct chromatic aberrations in the distance vision component (smallest principal power) while maintaining the multifocal capability through other diffraction zone configurations.
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 design significantly reduces the secondary halo, enhancing visual clarity and contrast sensitivity by compensating for longitudinal chromatic aberrations and maintaining sharp image focus on the retina.
Implementation Method 1
a diffractive optical structure, the diffractive optical structure comprising a first lens region with a plurality of first ring-shaped diffraction zones circumferential the principal optical axis of the eye lens, each diffraction zone having a principal sub-zone and a phase sub-zone
Data Source
AI summary
A diffractive eye lens having a front side, a rear side and an optical main axis, wherein the front side and/or the rear side has a spherical, an aspherical, a spherical-toric or an aspherical-toric basic shape, and the front side and/or the rear side has a diffractive optical structure. The diffractive eye lens allows for color correction and simultaneously improves visual properties by reducing a halo. The diffractive optical structure in a first lens region is designed such that, at a design wavelength, there is a significant diffraction efficiency for a phase deviation between the first main sub-zones of more than one wavelength and, for the first lens region, On average over all diffraction zones, a proportion of the main sub-zones on the diffraction zones is for example at least 94%, at least 95% and at best nearly 100%.