Additive Ophthalmic Lens Fabrication with Real-Time Geometric Feedback

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Solution Overview

Problem

Current additive manufacturing techniques face challenges in producing transparent ophthalmic lenses with precise geometric definitions and optical prescriptions, particularly in achieving smooth surfaces and precise control of curvature radii, which are essential for optical applications.

Innovation Solution

A method involving additive fabrication of ophthalmic lenses by depositing predetermined volume elements according to a target geometric envelope, with real-time monitoring and corrective actions based on geometric differences between the target and actual envelopes, allowing for adjustments such as adding additional elements or modifying the target geometry to ensure precise optical function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If additive manufacturing is used to manufacture ophthalmic lenses, then productivity and manufacturing flexibility are improved, but manufacturing precision and surface quality deteriorate

Engineering Contradiction:
Improvemanufacturing speedVSAvoidsurface precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the actual geometric envelope is determined during additive manufacturing and compared with the target geometric envelope. When deviations are detected, corrective actions are triggered to adjust the manufacturing process, ensuring precision is maintained while benefiting from additive manufacturing speed and flexibility.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent determines the actual geometric envelope during the manufacturing process rather than after completion. This preliminary detection allows for corrective actions to be taken while the lens is still being manufactured, preventing precision loss and eliminating the need for post-manufacturing corrections.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If high machining speed is used, then productivity is improved, but surface conformity deteriorates

Engineering Contradiction:
Improvemachining speedVSAvoidsurface conformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent dynamically adjusts the additive manufacturing process based on real-time monitoring of the actual geometric envelope. The manufacturing parameters can be modified during the process to maintain surface conformity while preserving the high productivity benefits of additive manufacturing, rather than using fixed high-speed parameters throughout.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system continuously monitors the actual geometric envelope and provides feedback to adjust manufacturing speed and parameters. When surface conformity deviations are detected, the system can slow down or adjust parameters locally, while maintaining high overall productivity through efficient error correction.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If low machining speed is used, then surface conformity is improved, but productivity deteriorates

Engineering Contradiction:
Improvesurface conformityVSAvoidmanufacturing speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies corrective actions only to specific zones where deviations are detected, rather than slowing down the entire manufacturing process. This partial correction approach maintains high productivity while ensuring surface conformity is achieved in critical areas through targeted adjustments.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The feedback mechanism allows the system to maintain high manufacturing speed overall, while only applying slower, more precise corrective actions to specific problem areas. This selective approach preserves productivity while ensuring surface conformity where needed.

Inventive Principle:
Principle #23Feedback

4Ease of manufacture

If voxel-by-voxel construction is used, then additive manufacturing capability is achieved, but dimensional control precision deteriorates

Engineering Contradiction:
Improveadditive manufacturing capabilityVSAvoiddimensional control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements feedback control that monitors the actual geometric envelope during voxel-by-voxel construction and compares it with the target envelope. This allows for real-time detection and correction of dimensional deviations, maintaining the ease of additive manufacturing while achieving precise dimensional control through continuous adjustment.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes manufacturing parameters during the voxel-by-voxel construction process based on detected deviations. By adjusting parameters such as voxel size, deposition rate, or material properties in response to real-time feedback, the system maintains dimensional control precision while preserving the flexibility of additive manufacturing.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3003691B1Process and machine for manufacturing an ophthalmic lens
Publication Date: 2020.12.02 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP3003691B1 patent drawingFigure 1~4
  • EP3003691B1 patent drawingFigure 5~6
  • EP3003691B1 patent drawingFigure 7~8

AI summary

The invention relates to a process for manufacturing an ophthalmic lens (10) having at least one optical function, characterised in that it comprises: a step (100) of additively manufacturing said ophthalmic lens (10) by depositing a plurality of preset volume elements of at least one material having a preset refractive index in order to form a target geometric envelope; a step of determining an actual geometric envelope at least once during the implementation of said additive manufacturing step (100); and a step of triggering a corrective action if there is in a zone a discrepancy larger than a preset threshold between said target geometric envelope and said actual geometric envelope.