Digital Surface Topography Analysis for Ophthalmic Lens Quality Control
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Solution Overview
Problem
The digital surfacing process for manufacturing ophthalmic lenses lacks effective quality control, leading to artifacts and inefficiencies, as traditional methods are either costly or time-consuming, and existing quality control processes do not adequately address the positioning and deformation errors in lens manufacturing.
Innovation Solution
A computer-based process that determines at least six position parameters defining the relative position of a manufactured surface to a reference surface by providing nominal, measured, and deformation surfaces, and minimizing differences between these to control error surfaces and deformation parameters, thereby enhancing quality control and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional quality control methods are used to check each individual lens, then measurement precision is improved, but productivity deteriorates due to time consumption
Solution Approach 1:
The patent creates a digital copy (virtual model) of the lens surface through optical scanning, replacing physical inspection of each lens with analysis of the digital representation. This allows comprehensive quality control of manufacturing parameters without handling or measuring each individual lens physically, thus maintaining high measurement precision while preserving productivity
Solution Approach 2:
The patent performs quality control analysis on the manufactured surface before the lenses are actually produced in bulk. By analyzing the manufacturing process results preliminarily through surface topography measurement and virtual model comparison, potential defects are detected early, avoiding time-consuming individual lens inspection later while maintaining quality standards
2Productivity
If existing quality control processes are implemented, then manufacturing process control is improved, but measurement precision deteriorates due to artifacts in the results
Solution Approach 1:
The patent extracts and separately analyzes different components of surface deviation by comparing the measured surface topography with the virtual model. This separation allows identification of genuine manufacturing errors from artifacts, improving measurement precision by isolating true position parameter deviations from false signals
Solution Approach 2:
The patent introduces a virtual model as an intermediary between the measured surface and the quality control analysis. This virtual model serves as a reference that mediates the comparison process, enabling accurate differentiation between actual manufacturing deviations and measurement artifacts, thus improving position parameter determination accuracy
3Productivity
If digital surfacing process is used without adequate quality control, then productivity is improved, but manufacturing precision deteriorates due to lack of process control
Solution Approach 1:
The patent implements a feedback mechanism where the measured surface topography is compared with the virtual model, and the differences (position parameters and deformation parameters) are fed back to evaluate manufacturing quality. This allows real-time assessment of manufacturing precision during the digital surfacing process, enabling quality control without slowing down production
Data Source
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AI summary
Process implemented by computer means for determining position parameters defining the relative position of a manufactured derivable surface relative to a reference surface, the process comprising: - a nominal surface providing step (S1), - a measured surface providing step (S2), - a deformation surface providing step (S3), - a composed surface determining step (S4), and - a parameters determining step (S5) during which the position parameters and at least one deformation parameter defining the deformation surface are determined by minimizing the difference between the nominal surface and the composed surface.