Hybrid Ophthalmic Lens Diffractive Phase Element Depth of Focus
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Solution Overview
Problem
Current ophthalmic lenses, particularly intraocular lenses, face challenges in achieving an extended depth of focus without compromising resolution, and are sensitive to decentring, tilt, and position changes, often resulting in halos and ghost images during night vision due to incomplete correction of spherical aberrations and uncertainties in lens power measurement.
Innovation Solution
A method for determining the configuration of ophthalmic lenses that separates the determination of depth of focus and resolution by using a diffractive phase element structure, which can be replaced by an aspheric surface, to create a hybrid lens with extended depth of focus and field, maintaining a constant modulation transfer function across different segments, thereby improving visual acuity and reducing sensitivity to alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spherical aberrations are completely corrected using an aspheric surface, then resolution is improved, but depth of focus and depth of field decrease
Solution Approach 1:
The lens is divided into two functional surfaces: one aspheric surface for correcting spherical aberrations and improving resolution, and one diffractive surface for extending depth of focus. This segmentation allows each surface to independently optimize its function without compromising the other.
Solution Approach 2:
The lens combines two different optical surface types (aspheric and diffractive) into a hybrid structure. The aspheric surface addresses spherical aberration while the diffractive surface extends depth of focus, creating a composite optical element that achieves both goals simultaneously.
2Length of moving object
If spherical aberrations are not corrected, then depth of focus is maintained, but resolution deteriorates
Solution Approach 1:
The lens is divided into two functional surfaces: one aspheric surface for correcting spherical aberrations and improving resolution, and one diffractive surface for extending depth of focus. This segmentation allows each surface to independently optimize its function without compromising the other.
Solution Approach 2:
The lens combines two different optical surface types (aspheric and diffractive) into a hybrid structure. The aspheric surface addresses spherical aberration while the diffractive surface extends depth of focus, creating a composite optical element that achieves both goals simultaneously.
3Measurement precision
If lens power is increased to improve visual acuity, then resolution is improved, but sensitivity to decentring and tilt increases
Solution Approach 1:
The invention changes the optical parameters by introducing a diffractive phase element with specific profile characteristics that create multiple focal points. This parameter change allows the lens to maintain high visual acuity while the distributed focal points reduce sensitivity to alignment errors compared to a single high-power focal point.
4Measurement precision
If a single focal point is used to correct vision, then visual acuity is improved, but halos and ghost images appear during night vision
Solution Approach 1:
The lens is divided into two functional surfaces: one aspheric surface for correcting spherical aberrations and improving resolution, and one diffractive surface for extending depth of focus. This segmentation allows each surface to independently optimize its function without compromising the other.
Solution Approach 2:
The lens combines two different optical surface types (aspheric and diffractive) into a hybrid structure. The aspheric surface addresses spherical aberration while the diffractive surface extends depth of focus, creating a composite optical element that achieves both goals simultaneously.
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 solution allows for independent control of depth of focus and resolution, providing improved visual acuity with reduced halos and ghost images, and adaptability to individual ocular characteristics, while maintaining a constant modulation transfer function, thus enhancing the accuracy and effectiveness of ophthalmic lenses.
Implementation Method 1
a diffractive phase element structure, which can be replaced by an aspheric surface, to create a hybrid lens with extended depth of focus and field
Data Source
AI summary
The invention relates to a method for making an ophthalmic lens intended to correct the visual acuity of a user, comprising the steps of determining the shape of a base optical corrective element, determining the profile of a phase element structure, said determination comprising the steps of defining a desired depth of focus of said ophthalmic lens; calculating the phase distribution to be created at the entrance pupil of the lens, selecting a phase distribution and performing an iterative calculation to obtain the depth of focus, finding the phase which minimizes the differences between the effective phase distribution and the desired phase distribution and of converting the phase data into geometrical data to define the profile of the phase distribution structure and juxtaposing the resulting phase element structure and the base optical corrective element.