ED Material Diagnostic Ophthalmic Lens Chromatic Aberration
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Solution Overview
Problem
Diagnostic ophthalmic lenses used with indirect ophthalmoscopes and slit lamp biomicroscopes suffer from chromatic aberration due to high dispersion materials, degrading image quality and performance.
Innovation Solution
A diagnostic ophthalmic lens design utilizing a single lens element made from Extra-low Dispersion (ED) materials with an Abbe Number greater than 80, such as fluor-crown glass, fluorites, or polymers, which reduces chromatic dispersion and improves image quality by minimizing angular dispersion of colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transparent materials are used for diagnostic ophthalmic lenses, then the lens can be manufactured with standard materials, but chromatic aberration degrades image quality due to high dispersion
Solution Approach 1:
The patent applies parameter changes by selecting materials with specific optical properties - Extra-low Dispersion (ED) glass with Abbe Number Vd>80, fluorite crystals with Vd>90, or polymers with Vd>55. By changing the material parameter (Abbe Number) to higher values, the chromatic dispersion is reduced, thereby improving image quality and reducing chromatic aberration in the diagnostic ophthalmic lens
Solution Approach 2:
The patent employs composite materials by combining ED glass elements with fluorite crystal elements in a multi-element lens design. This composite approach leverages the complementary optical properties of both materials - ED glass provides structural integrity and low dispersion, while fluorite contributes extreme low dispersion characteristics - achieving superior chromatic aberration correction that neither material could achieve alone
2Object-generated harmful factors
If fluorite materials are used to achieve high Abbe Numbers, then chromatic dispersion is reduced, but mechanical strength decreases due to soft and fracture-prone crystalline structure
Solution Approach 1:
The patent applies local quality by assigning different materials to different positions and functions within the lens system. Fluorite crystals are used in specific elements where extreme low dispersion is most beneficial for chromatic aberration correction, while ED glass is used in other elements where mechanical strength and durability are prioritized. This localized material assignment optimizes both optical performance and mechanical reliability
Solution Approach 2:
The patent uses ED glass as an intermediary material that bridges the gap between fluorite's optical excellence and mechanical weakness. ED glass provides a compromise solution with good mechanical properties and sufficiently low dispersion (Vd>80), serving as a mediator that reduces the reliance on fragile fluorite while still achieving effective chromatic aberration correction in the overall lens design
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 use of ED materials with high Abbe Numbers significantly reduces chromatic aberration, resulting in improved image quality and performance by forming a flat, magnified indirect image of the retina for convenient observation.
Implementation Method 1
Dispersion of a material is its variation of refractive index (n) with respect to wavelength (λ). For visible light, most transparent materials have the following relationship between the changes in its index of refraction (n) verses wavelength (λ)
Implementation Method 2
at a material interface, such as air-to-glass, the angle at which light is refracted will vary with wavelength, causing an angular dispersion of colors
Data Source
AI summary
An improved diagnostic ophthalmic lens using extra-low dispersion material, defined by having an Abbe Number, Vd>80, is provided. Such a single element diagnostic ophthalmic lens may be used for examination of the eye in conjunction with either an Indirect Opthalmoscope or a Slit Lamp Biomicroscope.