Diffractive Eyeglass Lens for Astigmatic Aberration Control
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Solution Overview
Problem
Refractive progressive lenses face limitations in image quality and field of vision due to astigmatic aberrations caused by Minkwitz's differential geometric theorem, restricting the expansion of near and far zones.
Innovation Solution
A spectacle lens utilizing diffraction structures that deflect light by constructive interference, allowing for sharp vision across different distance ranges without astigmatic aberrations, by using a phase object with a multiplicity of diffraction structures that convert light into specific diffraction orders with high efficiency, overcoming the limitations of refractive progressive lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If refractive progressive lenses are used to provide varifocals for different viewing distances, then the field of vision is expanded, but astigmatic aberrations occur in the peripheral regions due to Minkwitz's differential geometric theorem
Solution Approach 1:
The patent replaces the refractive optical system with a diffractive optical system. Instead of using a continuously varying refractive index to achieve varifocals (which causes astigmatic aberrations per Minkwitz's theorem), the invention uses diffraction structures that redirect light rays through discrete diffraction orders. This substitution of the optical mechanism eliminates the geometric constraints that cause astigmatism while maintaining the varifocal capability across different viewing distances.
Solution Approach 2:
The patent changes the fundamental optical parameter from refractive index variation to diffraction angle control. By using diffraction structures with specific grating parameters (period, orientation, and depth modulation), the system achieves precise control over light redirection angles without being constrained by the differential geometric limitations of refractive surfaces. This parameter transformation allows for aberration-free peripheral vision.
2Area of moving object
If the progression channel is made wider to expand the field of vision, then more viewing distance ranges are accessible, but uncorrectable astigmatic aberrations increase according to Minkwitz's theorem
Solution Approach 1:
The invention substitutes the refractive progression channel mechanism with a diffractive light redirection system. The diffraction structures are configured to redirect light from different object distances to the retina without requiring a continuously varying refractive index. This allows for a wider progression channel (greater viewing distance range) while avoiding the astigmatic aberrations that inevitably occur in refractive progressive lenses due to Minkwitz's differential geometric theorem.
3Adaptability or versatility
If refractive progressive lenses are used to correct ametropia for different distances, then multiple focal lengths are achieved, but imaging quality deteriorates in peripheral regions
Solution Approach 1:
The patent replaces the refractive system with a diffractive system that achieves multiple focal lengths through discrete diffraction orders. Each diffraction structure is designed to redirect light from specific object distances to corresponding retinal locations with high precision. This diffractive approach maintains sharp imaging quality across all focal lengths, including peripheral viewing angles, because diffraction can be engineered to redirect rays precisely without the continuous curvature variations that cause astigmatism in refractive lenses.
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 clear vision across various distance ranges without astigmatic aberrations, improving imaging quality and expanding the field of vision by using diffraction to deflect light, rather than refraction, thus avoiding the limitations imposed by Minkwitz's theorem.
Implementation Method 1
a phase object (20, 22) with a multiplicity of diffraction structures (24, 26), by means of which light incident on the spectacle lens at a specific angle of incidence is diffracted
Implementation Method 2
the diffraction of light is understood to mean the physical phenomenon of the change in the phase of the light caused by a phase object due to interactions between light and matter
Data Source
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AI summary
The invention relates to an eyeglass lens for an observing person, comprising a body that is transparent or at least partially transparent to the light, which body has a phase object (20), which directs the light incident at an angle of incidence (α) on a side facing away from the observing person in a direction that depends on the wavelength (λ) of the light and on the angle of incidence (α) of the light. According to the invention, the phase object (20) has a plurality of diffraction structures (24, 26), which diffract monochromatic light of the wavelength 380 nm ≤ λ ≤ 800 nm with the diffraction efficiency η ≥ 70% in one and the same diffraction order│m│≥ 1 when the monochromatic light is incident on the side facing away from the observing person at an angle of incidence (α) that lies within a 15° wide diffraction-structure-specific angle interval that depends on the wavelength of the light.