Segmented Progressive Spectacle Lens Design for Astigmatic Error Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Progressive power lenses suffer from increasing residual astigmatic error with distance from the umbilical line, leading to discomfort and optical aberrations like double images, while multifocal lenses have aesthetic drawbacks and optical issues due to separating lines.
Innovation Solution
A computer-implemented method for determining a spectacle lens design composed of segments with discontinuities in refractive index and surface shape, limiting residual astigmatic error to 1.5 D and focal power steps to 1.0 D or less, ensuring a smooth transition between distance and near vision without visible separating lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If progressive power lenses are designed with continuous freeform surfaces optimized for distance and near vision, then the lens provides smooth transition between focal powers, but residual astigmatic error increases with distance from the umbilical line causing optical aberrations and discomfort
Solution Approach 1:
The progressive power lens is divided into multiple segments with discontinuities in refractive index and/or surface shape. Each segment is optimized for specific visual zones, allowing control of residual astigmatic error in each region while maintaining overall progressive power transition. The segments are arranged to provide distance portion, near portion, and corridor regions with reduced optical aberrations.
Solution Approach 2:
Different segments of the lens are assigned different refractive indices and/or surface shapes tailored to their specific functional requirements. The peripheral zones have optimized local optical properties to reduce residual astigmatic error, while the central corridor maintains smooth progressive transition. This localized optimization allows each region to perform its specific visual function with minimal aberrations.
2Reliability
If multifocal lenses are designed with separating lines between distance and near portions, then the lens provides distinct focal zones, but the separating line is visible affecting aesthetic appearance and creates optical aberrations
Solution Approach 1:
The lens is segmented into multiple zones with different optical properties, but unlike traditional bifocals, the segment boundaries are not visible as separating lines. The discontinuities are in refractive index and/or surface shape rather than physical line markings, providing distinct focal zones while maintaining aesthetic appearance similar to conventional progressive lenses.
3Object-affected harmful factors
If segments with discontinuities in refractive index and surface shape are used, then residual astigmatic error is reduced to acceptable levels, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process controls key parameters including refractive index distribution, surface shape discontinuities, segment boundaries, and thickness variations. By precisely controlling these parameters during fabrication, the complex segmented structure can be produced with consistent optical quality. The parameters are optimized to achieve residual astigmatic error reduction while maintaining manufacturability through systematic control of geometric and material properties.
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 method reduces residual astigmatic error and optical aberrations, providing a comfortable and aesthetically pleasing progressive power lens with minimal double images, especially in peripheral zones, by optimizing segment combinations and refractive indices.
Implementation Method 1
spectacle lens design for a progressive power lens... composed of segments with discontinuities between neighboring segments in at least one of refractive index and surface shape
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A spectacle lens design and a progressive power lens with a distance portion (7), a near portion (9), a corridor (11) extending between the distance position (7) and the near portion (9), and peripheral zones delimited by the distance portion (7), the near portion (9) and the corridor (11) are provided. The spectacle lens design and the progressive power lens are composed of segments (1, 3.1-3.5, 5.1-5.5) with discontinuities between neighboring segments (1, 3.1-3.5, 5.1-5.5) in at least one of refractive index and surface shape, where the segments (1, 3.1-3.5, 5.1-5.5) include a central segment (1) forming the distance portion (7), the near portion (9) and the corridor (11), and peripheral segments (3.1-3.5, 5.1-5.5). In addition, a method of determining a spectacle lens design for a progressive power lens is provided. According to a first aspect, of the spectacle lens design and a progressive power lens, the peripheral segments (3.1-3.5, 5.1-5.5) are annular segments. According to a second aspect, of the spectacle lens design and a progressive power lens, combinations of refractive indices and surface shapes are assigned such to each segment (1, 3.1-3.5, 5.1-5.5) that a residual astigmatic error does not exceed a given threshold of 1.5 D According to a third aspect, of the spectacle lens design and a progressive power lens, combinations of refractive indices and surface shapes are assigned such to each segment (1, 3.1-3.5, 5.1-5.5) that steps in focal power at the borders (6) between neighboring segments (1, 3.1-3.5, 5.1-5.5) are not larger than 1.0 D.