Hybrid Diffractive Liquid Crystal Lens for Presbyopia
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Solution Overview
Problem
Current ophthalmic lenses for presbyopia, such as bifocal, trifocal, and liquid crystal adaptive lenses, suffer from limitations like bulky design, low light efficiency, slow switching times, high driving voltage, and power-failure issues, making them unsuitable for providing adjustable focusing power for near and distant vision effectively.
Innovation Solution
A varifocal liquid crystal (LC) adaptive lens with a hybrid diffractive lens structure, featuring a large aperture, high light efficiency, fast switching time, low driving voltage, and a power-failure-safe configuration, utilizing diamond turning and molding techniques for fabrication, with a thin LC layer and continuous conductive electrodes for continuous focal length adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a thick layer of liquid crystal (>400 um) is used in electrically controllable liquid-crystal refractive lenses, then the lens can be controlled electrically, but optical scattering caused by the thick LC layer results in low transmission and lengthy response and recovery times
Solution Approach 1:
The patent changes the key parameter of liquid crystal layer thickness from >400 um to a thin layer of 3-50 um. This parameter change fundamentally resolves the contradiction by enabling electrical controllability while minimizing optical scattering, thereby achieving both high light transmission and fast response times simultaneously
2Length of moving object
If a Fresnel lens substrate is used to reduce LC lens thickness, then the lens thickness is reduced, but the lens is optically active in the electrically off-state which is not desirable for ophthalmic applications
Solution Approach 1:
The patent uses a diffractive optical element (DOE) with a specific phase profile that copies the desired lens focusing effect. The DOE is designed with a phase profile that is inactive in the off-state, meaning it does not alter light propagation when no voltage is applied. This allows the lens to remain optically neutral during power failures while maintaining thin thickness through the diffractive structure
3Adaptability or versatility
If area division techniques (bifocal, trifocal, progressive lenses) are used, then the eye can focus on both near and distant objects, but the field of view for each type of vision is limited to a narrow corridor
Solution Approach 1:
The patent employs a dynamically adjustable liquid crystal lens where the focal length can be continuously changed by varying the applied voltage. This dynamic adjustment allows the entire lens aperture to be used for any given focal length, providing a full field of view for each vision distance rather than limiting the user to narrow corridors as in static area division lenses
4Adaptability or versatility
If simultaneous vision concept is used in multifocal contact and intraocular lenses, then light is diffracted into several orders for different focal lengths, but the light efficiency is low and users must selectively suppress blurred images
Solution Approach 1:
The patent replaces the passive simultaneous vision approach with an active, electrically controlled liquid crystal lens system. By using voltage to dynamically adjust the focal length, the system substitutes the mechanical/optical complexity of simultaneous vision with an electrically controlled single-focus mechanism, achieving high light efficiency and eliminating the need for users to suppress blurred images
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 LC lens provides continuous tunability, high light transmission, and fast response times, enabling efficient adjustment of focusing power across a large aperture, suitable for ophthalmic applications, including presbyopia correction without the drawbacks of existing technologies.
Implementation Method 1
the LC layer 510 has a negative dielectric anisotropy... a controller 982 for varying a voltage across the LC layer 510... the focusing power of the LC lens 502 is varied as a function of the voltage
Implementation Method 2
a varifocal lens that is continuously tunable... employing a hybrid diffractive lens structure
Data Source
AI summary
An adaptive liquid crystal lens system comprising a first substrate assembly, a second substrate assembly having a continuous phase profile, and a liquid crystal layer disposed between the first and second substrate assemblies. The first substrate assembly includes a first transparent substrate, an alignment layer, and a first conductive layer. The first conductive layer is disposed on the bottom surface of the first transparent substrate and adjacent to the top surface of the alignment layer. The second substrate assembly includes a second transparent substrate, a lens having a grooved surface, and a second conductive layer. The second conductive layer is a continuous layer adjacent to the lens. The liquid crystal layer is received in the grooves of the lens, and is adjacent to the bottom surface of the alignment layer. The alignment layer causes the liquid crystal material in the liquid crystal layer to be in a homeotropic state.