Multifocal Lens Structure Without Geometric Steps
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Solution Overview
Problem
Existing multifocal lenses, particularly trifocal lenses, are complex and costly to manufacture due to geometric steps and varying refractive power profiles between zones, leading to high production costs.
Innovation Solution
A multifocal lens design with equal refractive powers within inner and outer subzones, combined with specific area ratios, eliminates geometric steps and simplifies manufacturing by utilizing interference phenomena to generate multiple refractive powers through diffraction, allowing for easy and economical production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If geometric steps are used between zones to create different refractive powers, then multiple refractive powers are achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical approach of using geometric steps (physical height differences) with an optical approach using interference phenomena. By utilizing interference between light from different subzones, the lens achieves multiple refractive powers without requiring physical steps, thereby simplifying manufacturing while maintaining multifocality.
Solution Approach 2:
The patent changes the parameter of refractive power distribution by using equal refractive powers for all inner subzones and all outer subzones, with specific area ratios (30:70 to 70:30). This uniform parameter approach within zones, combined with interference, achieves multiple refractive powers without the manufacturing complexity of varying step heights.
2Reliability
If phase subzones with varying refractive powers are used, then optical path length differences are achieved, but refractive force profile becomes complex and manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by assigning equal refractive powers to all inner subzones and all outer subzones within each main zone, creating a uniform refractive property distribution. This simplifies the refractive force profile compared to varying phase subzone refractive powers, while still achieving the required optical path length differences through interference.
Solution Approach 2:
The patent creates equipotentiality in terms of refractive power within each subzone type (all inner subzones have equal refractive power, all outer subzones have equal refractive power). This uniformity simplifies the overall refractive force profile and reduces manufacturing complexity compared to varying refractive powers across different subzones.
3Reliability
If alternating step heights are used in Fresnel zones, then optical path length differences of 0.65·λ and 1.35·λ are achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical system of alternating step heights with an optical interference system. By using interference between light from inner and outer subzones with equal refractive powers, the lens achieves the required optical path length differences (0.65·λ and 1.35·λ) without manufacturing complex step structures, thereby reducing production costs.
Solution Approach 2:
The patent employs equipotentiality by using equal refractive powers for all inner subzones and all outer subzones, eliminating the need for alternating step heights. This uniform approach achieves the same optical path length differences at lower manufacturing cost compared to the alternating step height design.
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 lens achieves efficient multifocality with reduced manufacturing complexity and cost, providing clear vision at various distances without visible steps, and can simulate or compensate for chromatic aberration in the human eye.
Implementation Method 1
the basis of the disclosed subject matter is the explicit consideration of the interference phenomena between light from the different subzones or main zones
Implementation Method 2
the multifocal lens of the disclosed subject matter enables a variety of divisions of the light intensity into its main refractive powers, e.g. an even division for good vision at a distance, medium distance and close up
Data Source
AI summary
A multifocal lens with at least three main refractive powers has a plurality of concentric annular main zones adjacent to each other. Each main zone is divided into an inner and an outer annular subzone of different refractive power. The lens is free of geometrical steps between all subzones, the refractive powers of all inner subzones are equal to each other, and the refractive powers of all outer subzones are equal to each other. Moreover, all inner and outer subzones share their respective main zone in an equal area ratio which is in a range of 30:70 to 70:30.