Free-Form Spectacle Lens Surface Fitting Optimization
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Solution Overview
Problem
Existing methods for fitting spectacle lenses to frames often result in noticeable impairments to the dioptric power, especially when the frame edge curve is complex, leading to suboptimal aesthetics and comfort.
Innovation Solution
A computer-implemented method that simultaneously optimizes a free-form surface and a second spectacle lens surface to minimize the difference between their edge curves and achieve intended dioptric power, ensuring accurate fitting without compromising optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing methods for fitting spectacle lenses to frames are used, then the fitting process is simplified, but noticeable impairments to dioptric power occur, especially with complex frame edge curves
Solution Approach 1:
The fitting process is divided into two independent optimization stages: first optimizing the front surface free-form parameters to match the frame edge curve, then optimizing the back surface parameters to achieve the prescribed dioptric power. This segmentation allows each stage to focus on its specific objective without compromising the other, resolving the contradiction between fitting simplicity and optical quality.
Solution Approach 2:
The front surface free-form parameters are determined in advance by fitting to the frame edge curve before the lens edging process. This preliminary action creates a customized front surface that perfectly matches the complex frame geometry, and then the back surface is optimized subsequently to maintain dioptric power, eliminating the need for iterative adjustments during manufacturing.
2Shape
If the spectacle lens is fitted closely to the frame edge curve, then aesthetics and comfort are improved, but the dioptric power is noticeably impaired
Solution Approach 1:
The lens surface is divided into front and back surfaces with independent optimization. The front surface free-form parameters are specifically optimized to match the frame edge curve shape, while the back surface parameters are independently optimized to achieve the prescribed dioptric power. This segmentation allows both shape correspondence and optical quality to be maximized simultaneously.
Solution Approach 2:
The front surface is given local quality through free-form customization to perfectly match the complex frame edge curve geometry, while the back surface maintains the quality required for optimal optical performance. This localized optimization of different surface properties resolves the contradiction between aesthetic shape matching and dioptric power preservation.
3Ease of manufacture
If conventional lens surfaces are used, then manufacturing is simpler, but the edge of the lens front surface noticeably deviates from the frame edge curve
Solution Approach 1:
The front surface transitions from a fixed conventional design to a dynamic free-form surface that can adapt to any frame edge curve geometry. By introducing free-form parameters that can be customized for each frame, the system achieves precise edge curve matching while maintaining manufacturing simplicity through automated optimization processes.
Solution Approach 2:
The front surface is transformed from a conventional fixed-parameter surface to a free-form surface with multiple adjustable parameters. These parameters are optimized to match the specific frame edge curve geometry, enabling precise customization without complicating the manufacturing process, as the optimization is performed computationally before manufacturing.
Data Source
AI summary
A computer-implemented method for fitting a spectacle lens, which has a first spectacle lens surface, a second spectacle lens surface, and at least one dioptric power to be obtained, to a spectacle frame with a certain frame edge curve is made available. In the method, a free-form surface formed on a first spectacle lens surface is fitted to the frame edge curve of the spectacle frame. The free-form surface is fitted to the frame edge curve by virtue of the free-form surface and the second spectacle lens surface being optimized with regard to minimizing the difference between the free-form surface edge curve and the frame edge curve and with regard to achieving the at least one dioptric power to be obtained with the spectacle lens.