Additive Manufacturing Optical Elements Using Gradient Curing Energy
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Solution Overview
Problem
Additive manufacturing technologies for ophthalmic lenses often result in optical defects due to the accumulation of interfaces between layers and traces of pixels from irradiating tools, leading to diffracting defects, which are critical when the lenses are used.
Innovation Solution
A method involving the use of curable materials where the first part of the optical element is irradiated with a curing surface energy below a predetermined threshold, allowing it to be in an intermediate state, and subsequent parts receive additional curing energy to merge efficiently, reducing interface defects by interpenetrating with continuous material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additive manufacturing is used to manufacture ophthalmic lenses layer-by-layer, then the lenses can be produced with complex shapes and customized designs, but optical defects appear at the interfaces between layers due to diffracting patterns
Solution Approach 1:
The patent changes the physical-chemical parameters of the curable material during manufacturing. By controlling the curing process parameters (energy threshold, curing depth) and using materials with specific refractive index gradients, the patent eliminates interface defects while maintaining customized lens designs. The material transitions from fully cured to partially cured states to ensure continuous optical properties across layers.
Solution Approach 2:
The patent employs composite curable materials that combine multiple components with different curing characteristics. These composite materials allow selective curing at different depths and rates, enabling the formation of continuous material properties across layer interfaces while maintaining design flexibility.
2Strength
If high curing energy is applied to fully harden each layer, then the layers gain sufficient strength, but diffracting defects are generated at the interfaces between layers
Solution Approach 1:
The patent applies local quality by differentiating the curing state across different regions of the lens. The surface layers remain partially cured while deeper layers are fully cured, creating a gradient structure. This local differentiation eliminates interface diffraction while maintaining overall structural strength through the cumulative effect of partially cured surface layers.
Solution Approach 2:
The patent uses partial action by applying curing energy below the threshold required for complete hardening of surface layers. This partial curing is sufficient to maintain structural integrity while preventing the formation of sharp interfaces that cause diffraction. The cumulative effect of multiple partially cured layers provides both strength and optical quality.
3Stability of the object's composition
If the first layer is fully cured before adding subsequent layers, then the structural stability is maintained, but the interface between layers creates optical defects
Solution Approach 1:
The patent applies preliminary action by partially curing surface layers before subsequent layers are added and cured. This preliminary partial curing provides sufficient structural stability to support additional layers while maintaining material continuity at interfaces. The partial curing state allows the material to remain slightly flexible, preventing sharp interface formation.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining a continuous curing process that extends through multiple layers. Rather than completing curing of one layer before starting the next, the curing action continues cumulatively through all layers, ensuring continuous material properties and eliminating discrete interfaces that would cause optical defects.
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 minimizes or avoids interface defects, ensuring the optical elements have continuous material properties and improved optical quality by allowing parts to interpenetrate effectively, reducing diffracting defects and enhancing the overall performance of the ophthalmic lenses.
Implementation Method 1
forming a first part of the optical element by irradiating the surface of the curable material of said first portion with a first curing surface energy
Data Source
AI summary
A method for manufacturing an optical element (100) from a curable material (50) using an additive manufacturing technology comprising steps of: providing a first portion of curable material (50), forming a first part of the optical element by irradiating the surface (55) of the curable material with a first curing surface energy, the first curing surface energy being strictly lower than a first predetermined energy threshold and higher than a second predetermined threshold, and forming, after the irradiation of the first part with the first curing surface energy, at least a second part of the optical element, distinct from the first part of the optical element, by irradiating, with at least a second curing surface energy, the surface of the curable material, the second curing surface energy irradiating both the second part of the optical element (100) and at least a portion of the first part of the optical element, the sum of the first curing surface energy and the at least second curing surface energy being higher than or equal to the first predetermined energy threshold. A manufacturing system (1) for manufacturing an optical element.