Multifocal Diffractive Lens Central Zone Optimization

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Solution Overview

Problem

Existing multifocal diffractive lenses face challenges in optimizing optical performance for simultaneous bifocal vision, particularly in determining the surface area of the central diffractive zone to achieve optimal image focus and reduce peripheral astigmatism.

Innovation Solution

A method to determine the surface area of the central diffractive zone in a multifocal diffractive lens system by optimizing the optical performance parameter ϕ, considering the pupil surface area, Modulation Transfer Functions, and brightness levels at focal points, which allows for the configuration of a simultaneously bifocal optical system with improved image transfer and reduced astigmatism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the surface area of the central diffractive zone is increased, then the optical performance for near vision is improved, but the peripheral astigmatism increases

Engineering Contradiction:
Improveoptical performanceVSAvoidperipheral astigmatism
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by systematically varying the surface area of the central diffractive zone (parameter φ) to optimize the balance between near vision optical performance and peripheral astigmatism. The method evaluates multiple parameter values to determine the optimal configuration that resolves the contradiction between these two opposing requirements.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the surface area of the central diffractive zone is optimized for one pupil size, then the optical performance is improved for that specific case, but the performance degrades for other pupil sizes

Engineering Contradiction:
Improveoptical performanceVSAvoidperformance across different pupil sizes
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by designing an optimization method that considers multiple pupil sizes simultaneously. The evaluation process assesses optical performance across a range of pupil surface area values, seeking a central zone configuration that provides acceptable performance for various pupil conditions, thereby making the lens adaptable to different lighting conditions and individual variations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances the optical performance of multifocal lenses by optimizing the surface area of the central diffractive zone, leading to improved image focus and reduced peripheral astigmatism, thereby enhancing vision quality for both near and far distances.

Implementation Method 1

a diffractive lens component configured to be simultaneously bifocal

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP2912517B1A system comprising a multifocal diffractive lens component
Publication Date: 2018.08.22 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP2912517B1 patent drawingFigure 1
  • EP2912517B1 patent drawingFigure 2
  • EP2912517B1 patent drawingFigure 3

AI summary

A simultaneously bifocal optical system defined by a first system focal point and a second system focal point and a pupil, said system comprising a simultaneously bifocal diffractive lens component having a first focal point, a second focal point and a plurality of diffractive zones (101_1-101_n), the plurality of diffractive zones including a central zone (101_1) and a plurality of annular concentric zones (101_2-101_n) surrounding the central zone, the lens component having a first optical power and a second optical power associated with the first focal point and the second focal point respectively, the first focal point and the second focal point respectively corresponding to points of convergence of the most luminous orders of diffraction generated by the lens component for a nominal wavelength, the first system focal point and the second system focal point having a position dependent upon the value of the first optical power and the second optical power of the lens respectively, wherein the central zone has a surface area value determined as a function of the pupil of the optical system, of the first optical power and of the second optical power.