Multifocal Diffractive Ophthalmic Lens Intermediate Vision
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Solution Overview
Problem
Conventional multifocal diffractive lenses, particularly trifocal lenses, face challenges in providing a continuous and clear range of vision at intermediate distances due to the division of light energy among multiple focal points, resulting in gaps or poor vision quality at common working distances.
Innovation Solution
A multifocal diffractive ophthalmic lens design that suppresses one intermediate diffractive order to enhance continuity of vision, distributing light energy more effectively to produce at least three foci, including an intermediate focus closer to either distance or near vision, thereby providing a broader range of vision and sharper focus at intermediate distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light energy is divided among multiple focal points in conventional trifocal lenses, then multiple focal points are achieved, but vision continuity at intermediate distances deteriorates
Solution Approach 1:
The patent changes the diffraction efficiency parameters of the diffractive lens to achieve a non-uniform distribution of light energy among focal points. Specifically, it creates a first diffractive focus with higher diffraction efficiency and a second diffractive focus with lower diffraction efficiency, allowing one focus to dominate at intermediate distances while maintaining multiple focal points, thus resolving the contradiction between multi-focality and vision continuity
Solution Approach 2:
The patent applies different local qualities to different focal points by assigning different diffraction efficiencies to different diffractive orders. The first diffractive focus is optimized for intermediate distances with higher energy concentration, while the second diffractive focus serves other distance ranges with lower energy, creating localized optimization that maintains overall vision continuity
2Adaptability or versatility
If light energy is distributed evenly among multiple foci, then multiple focal points are provided, but energy concentration at each focus is reduced
Solution Approach 1:
The patent modifies the diffraction efficiency parameters to create an asymmetric energy distribution pattern. By setting the first diffractive focus to have higher diffraction efficiency than the second, the system concentrates more energy where needed for intermediate vision while still maintaining the presence of multiple focal points, thus achieving both multi-focality and adequate energy concentration
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 design improves vision continuity by allocating more energy to relevant foci, offering sharper intermediate vision and reducing unwanted light effects, thus addressing the limitations of conventional trifocal lenses by providing a clearer focus at common working distances like 60 cm.
Implementation Method 1
The diffractive element produces constructive interference in at least four consecutive diffractive orders
Implementation Method 2
The constructive interference produces a near focus, a distance focus corresponding to the base power of the ophthalmic lens, and an intermediate focus between the near focus and the distance focus
Data Source
AI summary
A multifocal ophthalmic lens includes an ophthalmic lens and a diffractive element. The ophthalmic lens has a base curvature corresponding to a base power. The diffractive element produces constructive interference in at least four consecutive diffractive orders corresponding a range of vision between near and distance vision. The constructive interference produces a near focus, a distance focus corresponding to the base power of the ophthalmic lens, and an intermediate focus between the near focus and the distance focus.