Aspheric Spectacle Lens Design for Astigmatism Correction
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Solution Overview
Problem
Existing progressive power lens designs fail to optimize the aspheric design for combined refracting surfaces, leading to suboptimal correction of astigmatism and cylindrical powers, resulting in increased astigmatism and lens thickness.
Innovation Solution
A method for designing spectacle lenses with combined refracting surfaces, where reference lines are established from the geometric center to determine optimal aspheric addition amounts, allowing for precise interpolation and application of aspheric surfaces to both distance-use and near-use areas, effectively addressing the refractive power changes due to cylindrical power and axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spherical design is used for progressive power lens, then manufacturing is simpler, but astigmatism is increased and optical capability is reduced
Solution Approach 1:
The patent applies aspheric design parameters to the progressive power lens, changing the surface curvature parameters from spherical to aspheric. This allows optimization of the refractive surface to reduce astigmatism and improve optical capability while maintaining manufacturability through systematic parameter determination methods.
Solution Approach 2:
The patent transitions from spherical surfaces to aspheric surfaces in the progressive power lens. The aspheric design modifies the curvature of the refracting surface to better correct optical aberrations, particularly astigmatism, while the patent provides methods to determine optimal aspheric parameters for manufacturing.
2Reliability
If aspheric design is applied to progressive power lens, then astigmatism is reduced and optical capability is improved, but lens thickness is increased
Solution Approach 1:
The patent applies aspheric design selectively to specific regions of the progressive power lens, particularly the distance and near use areas, while maintaining appropriate thickness control. The aspheric parameters are optimized locally to reduce astigmatism without uniformly increasing lens thickness across the entire lens.
Solution Approach 2:
The patent optimizes aspheric parameters to achieve the right balance between optical performance and lens thickness. By carefully selecting and determining aspheric coefficients, the patent reduces astigmatism and improves optical capability while controlling lens thickness through parameter optimization rather than uniform thickening.
3Reliability
If aspheric design is applied to combined refracting surface with astigmatic and progressive powers, then correction of cylindrical power is improved, but design complexity is increased
Solution Approach 1:
The patent segments the determination of aspheric parameters into distinct steps: establishing reference lines, determining parameters at reference points, and interpolating between references. This segmented approach simplifies the complex task of designing combined astigmatic and progressive surfaces by breaking it into manageable computational steps.
Solution Approach 2:
The patent performs preliminary actions by establishing reference lines and determining aspheric parameters at these reference positions before interpolating to complete the surface design. This preliminary determination at key points simplifies the overall design process and makes the complex combined surface design more systematic and manageable.
Data Source
AI summary
A method of designing a spectacle lens having a combined refracting surface in at least one of two refracting surfaces at object and eye sides structuring the spectacle lens, wherein the combined refracting surface has an astigmatic refracting surface combined with a progressive refracting surface having a distance-use area, a near-use area different in refractive power from the distance-use area and a progressive area having a refractive power progressively changing between those.