Diffractive Multi-Focal Lens With Overlapping Zone Profiles
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Solution Overview
Problem
Conventional diffractive multi-focal lenses have limited freedom in setting intermediate focal point positions, leading to difficulties in viewing intermediate distances, especially with the increasing need for personal computer use, and inefficient energy distribution due to unnecessary focal points.
Innovation Solution
A diffractive multi-focal lens with a novel structure featuring overlapping zone profiles, where the addition powers of the first and second zone profiles are determined by specific relational expressions, allowing for the generation of at least three focal points with high precision and flexibility in focal point positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional diffractive multi-focal lenses use standard Fresnel zone constitution, then the lens can provide basic multi-focal functionality, but the freedom in setting intermediate focal point positions is limited
Solution Approach 1:
The diffractive structure is divided into multiple zone profiles (first zone profile, second zone profile, etc.) with different zone pitches. Each zone profile can be independently designed and overlapped to create multiple focal points at different positions, enabling flexible setting of intermediate focal points while maintaining manageable structural complexity through modular design
Solution Approach 2:
Multiple zone profiles with different zone pitches are overlapped and combined in the same radial direction from the optical axis. This merging of different zone profiles allows simultaneous generation of multiple focal points (including intermediate focal points) from a single diffractive structure, achieving versatile focal point positioning without proportionally increasing overall structure complexity
2Use of energy by moving object
If conventional diffractive multi-focal lenses generate multiple focal points, then near and far vision are covered, but unnecessary focal points cause energy distribution inefficiency
Solution Approach 1:
Different zone profiles are assigned to different radial regions of the lens aperture. The first zone profile with a specific zone pitch generates focal points for certain vision distances, while the second zone profile with a different zone pitch generates focal points for other distances. This local differentiation allows energy to be directed to specific focal points needed for particular viewing distances, improving energy distribution efficiency while maintaining visual clarity through targeted focal point generation
3Measurement precision
If the addition power is increased to improve near vision, then the focal point position for near vision moves closer, but the intermediate focal point setting becomes more constrained
Solution Approach 1:
The diffractive structure incorporates multiple zone profiles with different zone pitches that can be independently adjusted. When addition power changes, the system can dynamically select or adjust which zone profiles are active or how they are overlapped, allowing precise control of focal point positions while maintaining flexibility in intermediate focal point setting. This dynamic adaptability enables the lens to optimize focal point distribution for different addition power 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
Enables the setting of intermediate focal points closer to the near focal point, improving vision for intermediate distances, such as personal computer screens, while reducing unnecessary focal points to enhance energy efficiency and visual clarity.
Implementation Method 1
a plurality of focal points are given by the mutual interference effect of light waves that passed through the plurality of diffractive structures (zones)
Implementation Method 2
a plurality of focal points are given by the mutual interference effect of light waves that passed through the plurality of diffractive structures (zones)
Implementation Method 3
0th order diffracted light is the focal point for far vision, and +1 order diffracted light is the focal point for near vision
Data Source
Figure 1
Figure 2A~2E
Figure 3A~3C
AI summary
A diffractive multi-focal lens having a diffractive structure comprising a plurality of concentric circular zones, wherein: at least a portion of the diffractive structure is provided with an overlapping region in which at least two zone profiles overlap in the same region; in the overlapping region, at least a portion of a first zone profile has a zone pitch represented by a prescribed equation, and at least a portion of a second zone profile has a zone pitch represented by another prescribed equation; and an addition power P1 given by the first zone profile and an addition power P2 given by the second zone profile are determined by a prescribed relational expression, in which a and b are mutually different real numbers, and a value of a/b cannot be expressed by a natural number X or by 1/X.