Multifocal Intraocular Lens Axicon Depth of Focus
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Solution Overview
Problem
Existing multifocal diffractive lenses face challenges in manufacturing complexity and increased vision blurring due to severe light scattering caused by imperfect manufacturing conditions, especially as the number of focal points increases.
Innovation Solution
A multifocal lens design incorporating a central axicon portion, which includes a base lens, a diffractive lens with a central region and surrounding diffractive region, and an axicon portion protruding along the central axis to expand the depth of focus between focal points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of focal points in multifocal diffractive lenses is increased, then the vision coverage is improved, but the manufacturing complexity and light scattering increase
Solution Approach 1:
The lens is divided into two distinct functional regions: a central axicon portion and a surrounding diffractive lens portion. This segmentation allows each region to perform a specialized function - the axicon portion handles continuous focus expansion while the diffractive portion provides discrete focal points, thereby reducing overall manufacturing complexity while maintaining versatile vision coverage.
Solution Approach 2:
Different optical properties are assigned to different regions of the lens. The central region employs an axicon structure with linearly increasing refractive index to create continuous focus, while the peripheral region uses traditional diffractive patterns for discrete focal points. This local differentiation optimizes each region's performance and simplifies manufacturing requirements for each specific area.
2Adaptability or versatility
If the number of focal points in multifocal diffractive lenses is increased, then the vision coverage is improved, but vision blurring due to light scattering increases
Solution Approach 1:
By segmenting the lens into central axicon and peripheral diffractive regions, the patent reduces light scattering. The axicon portion creates a continuous focus gradient that guides light more precisely, while the diffractive portion handles specific focal points, thereby reducing unwanted light scattering and vision blurring while maintaining comprehensive vision coverage.
Solution Approach 2:
The axicon portion acts as an intermediary structure between the light source and the diffractive lens. It pre-conditiones the light by creating a continuous focus gradient before the light reaches the diffractive region, which reduces the severity of light scattering and minimizes vision blurring effects.
3Adaptability or versatility
If a surface-relief shape with multiple diffraction patterns is used, then multiple focal points are achieved, but the manufacturing difficulty increases
Solution Approach 1:
The complex multifocal function is segmented into two simpler components: a central axicon structure and a peripheral diffractive pattern. This segmentation reduces manufacturing difficulty because each component can be fabricated using simpler, more established techniques compared to creating a single complex surface-relief shape with multiple diffraction patterns.
Solution Approach 2:
Instead of applying a uniform complex surface-relief shape across the entire lens, the patent applies different structures to different regions. The central region uses an axicon structure that is easier to manufacture, while the peripheral region uses conventional diffractive patterns, thereby reducing overall manufacturing difficulty while maintaining multiple focal points capability.
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 effectively expands the depth of focus between focal points, improving vision clarity and reducing blurring, particularly between near and intermediate distances, thus enhancing the functionality of multifocal lenses.
Implementation Method 1
a diffractive lens formed on the base lens, provided with a central region and a diffractive region surrounding the central region, and configured to disperse the single focal point into multiple focal points to form multiple focal points
Implementation Method 2
an axicon portion formed in the central region to protrude in a central axis direction of the base lens such that a depth of focus is expanded between the multiple focal points
Data Source
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AI summary
The present invention relates to a composite diffractive intraocular lens having one or more optical magnifications or focal lengths, the lens including: a base lens forming a single focal point; a diffractive lens formed on the base lens, provided with a central region and a diffractive region surrounding the central region, and configured to disperse the single focal point into multiple focal points to form multiple focal points; and an axicon portion formed in the central region to protrude in a central axis direction of the base lens such that a depth of focus is expanded between the multiple focal points.