Spectacle Lens Magnification Calculation Method
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Solution Overview
Problem
Current methods for calculating the magnification and distortion of spectacle lenses are time-consuming and inefficient, especially for aspherical or progressive surfaces, as they require extensive ray tracing and do not directly account for these factors during optimization, leading to suboptimal performance and wearer acceptance issues.
Innovation Solution
A method that calculates local magnification and distortion by tracing a central main beam and determining the local wave front curvatures, allowing for precise calculation without additional ray tracing, and incorporates these factors into the optimization process to minimize performance deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classical ray tracing methods are used to calculate magnification and distortion of spectacle lenses, then measurement precision is improved, but computing time increases significantly
Solution Approach 1:
The patent extracts only the essential information needed for magnification and distortion calculation from the ray tracing process. Instead of performing complete ray tracing for multiple beams, the method uses a simplified approach that traces only the central beam and calculates magnification/distortion from the known lens surface geometry and refraction at the central beam path, eliminating unnecessary computational steps while maintaining precision.
Solution Approach 2:
The patent performs preliminary calculation of lens surface parameters and optical properties before the actual magnification and distortion calculation. By pre-computing surface curvatures, refractive indices, and geometric parameters, the method avoids repeating these calculations during the measurement process, significantly reducing computing time while preserving calculation accuracy.
2Measurement precision
If additional beams are traced to account for asymmetrical surfaces and viewing directions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies different calculation approaches for different regions of the lens based on local characteristics. For asymmetric surfaces, the method calculates magnification and distortion specifically for the central beam path while accounting for local surface geometry and orientation. This allows precise measurement for each viewing direction without requiring complex multi-beam tracing for the entire lens, reducing overall system complexity while maintaining local measurement accuracy.
3Ease of manufacture
If magnification and distortion are not directly accounted for during optimization, then ease of manufacture is improved, but manufacturing precision worsens
Solution Approach 1:
The patent implements a feedback mechanism where magnification and distortion values calculated using the simplified method are fed back into the lens optimization process. The calculation method provides precise magnification and distortion measurements that inform subsequent lens design adjustments, allowing iterative optimization that directly accounts for these optical properties while maintaining manufacturing simplicity through the efficient calculation approach.
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
This approach significantly reduces computing time and allows for precise determination of magnification and distortion, improving the static and dynamic visual impression and tolerance of spectacle lenses, leading to enhanced wearer acceptance.
Implementation Method 1
a main beam HS originating from a predetermined or predeterminable infinitesimally small object and determined by ray tracing, which main beam, after the refraction by the spectacle lens, extends through the rotation point of the eye, through the entrance pupil of the eye or through the principal plane of the eye
Data Source
AI summary
The invention relates to a method for calculation of the local magnification and/or the local distortion of a spectacle lens in at least one predetermined or predeterminable viewing direction, with the spectacle lens being designed to correct a refraction deficit of an eye, and having at least one object-side surface and one second eye-side surface, comprising the following steps: Calculation for the predetermined or predeterminable viewing direction of the profile of a main beam which originates from a predetermined or predeterminable infinitesimally small object and, after refraction by the spectacle lens, passes through the rotation point of the eye, through the entrance pupil of the eye or through the principal plane of the eye; determination of the main curvatures and directions of a local wavefront associated with the main beam on refraction by the spectacle lens; calculation of the local magnification and/or the local distortion of the spectacle lens from the determined main curvatures and directions of the local wavefront, the data relating to the profile of the main beam, and the data relating to the spectacle lens.