Multifocal Lens Diffractive Profile Optimization
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Solution Overview
Problem
Multifocal lenses with diffractive structures suffer from suboptimal light intensity distribution and manufacturing complexities due to multiple profile peaks and non-usable focal points, leading to impaired image quality and increased production waste.
Innovation Solution
A lens design with a periodic diffractive profile having four portions per period, where one portion has a steeper gradient than the others, allowing for higher intensity components in usable focal points and simplifying manufacturing by reducing the number of profile peaks and angles, resulting in improved light distribution and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diffractive structures with four alternately monotonically rising and falling portions per period are used, then two diffractive focal points are produced, but manufacturing complexity increases due to multiple profile peaks and angles
Solution Approach 1:
The patent extracts and eliminates the unnecessary alternating rising and falling portions from the diffractive profile, retaining only the essential monotonically rising portions. This reduces the number of profile peaks and angles from four per period to two, simplifying manufacturing while preserving the ability to generate multiple diffractive focal points with optimized intensity distribution
Solution Approach 2:
The patent changes the parameter configuration of the diffractive profile by making portions monotonically rising instead of alternating rising and falling. This parameter change transforms the profile geometry to have fewer peaks and angles, directly reducing manufacturing complexity while maintaining optical functionality
2Manufacturing precision
If diffractive structures with multiple profile peaks are used, then multiple focal points are produced, but light intensity distribution becomes suboptimal
Solution Approach 1:
The patent applies local quality by making specific portions of the diffractive profile monotonically rising with optimized gradients, while other portions have different characteristics. This localized optimization ensures that light is properly directed into the desired focal points with high intensity, while unnecessary peaks that would create suboptimal intensity distribution are eliminated
Solution Approach 2:
The patent introduces asymmetry in the diffractive profile by having portions with different gradient characteristics - some portions are monotonically rising with specific gradients while adjacent portions have different properties. This asymmetric design optimizes light distribution into focal points, preventing the suboptimal intensity distribution that would result from symmetric alternating profiles
3Adaptability or versatility
If diffractive structures produce negative order focal points, then additional focal points are created, but image quality is impaired due to non-usable focal points
Solution Approach 1:
The patent converts the potentially harmful effect of negative order focal points into a beneficial outcome by designing the diffractive profile to image these negative order focal points onto the positive orders or onto the zeroth (refractive) order. This transformation ensures that light that would otherwise form non-usable focal points behind the retina is redirected to form usable images on the retina, improving image quality while maintaining the versatility of multiple focal points
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 higher intensity and contrast in usable focal points for near, intermediate, and distance vision, with reduced production complexity and increased accuracy, particularly at the lens periphery, leading to a more intensely colored and higher contrast image compared to prior art.
Implementation Method 1
a diffractive structure (5), the structure having a periodic profile in the radial direction of the lens plotted over the squared radius
Implementation Method 2
intensity components of the (originally) negative orders are imaged onto the positive orders used or onto the zeroth (refractive) order, resulting in a more intensely coloured, higher contrast image
Implementation Method 3
a refractive focal point... which may for example be used for near and distance vision (bifocal) or near, intermediate and distance vision (trifocal)
Data Source
AI summary
The invention relates to a multifocal lens (1) with a refractive focus (Fr) and with a diffractive structure (5) which, in the radial direction (r) of the lens (1), plotted across the squared radius (r2), has a periodic profile (6, 7, 8, 9), wherein the profile (6, 7, 8, 9) per period has four adjoining portions (6, 7, 8, 9) which are not differentiable at their connection sites (10, 11, 12, 13), wherein a first portion (9) has a monotonically falling function and the three further portions (6, 7, 8) have a monotonically rising function or vice versa, and wherein the further portion (7), which does not adjoin the first portion (9), has a greater pitch than the other further portions (6, 8).