Homogeneous Optical Elements via Additive Manufacturing

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Solution Overview

Problem

Additive manufacturing of eyewear lenses using stereolithography (SLA) and digital light processing (DLP) techniques faces challenges with non-homogeneity due to defects like micro-bubbles and variations in irradiance, leading to scattering and diffraction issues that degrade optical performance.

Innovation Solution

Implementing a diffuser between the light source and the resin in SLA systems, such as a silicone-based film or opal glass, and using transverse vibrations to minimize directional light effects, ensuring homogeneous irradiance and reducing defects, thereby enhancing the optical homogeneity of the lenses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If additive manufacturing (stereolithography/DLP) is used to produce eyewear lenses, then the need for semi-finished blanks is eliminated and material waste is reduced, but optical homogeneity deteriorates due to defects like micro-bubbles and irradiance variations

Engineering Contradiction:

Improvematerial wasteVSAvoidoptical homogeneity

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

A diffuser is introduced as an intermediary component between the light source and the resin in additive manufacturing systems. The diffuser scatters the light to create more uniform irradiance distribution across the resin surface, eliminating directional light effects and preventing defects like micro-bubbles and resin displacement. This intermediary element enables additive manufacturing to produce optically homogeneous lenses without material waste.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Transverse vibrations are applied to the light source or resin container during the additive manufacturing process. These vibrations disrupt the formation of directional light patterns and prevent the accumulation of defects such as micro-bubbles and resin displacement. The mechanical vibration ensures uniform light distribution and maintains optical homogeneity throughout the lens fabrication process.

Inventive Principle:

Principle #18Mechanical vibration

2Manufacturing precision

If mechanical grinding and polishing is used to shape lens surfaces, then arbitrary surfaces can be produced with high precision, but the process becomes complex, expensive, and energy-consuming

Engineering Contradiction:

Improvesurface accuracyVSAvoidmachinery complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical grinding and polishing system with an additive manufacturing system using stereolithography or DLP technology. By substituting mechanical removal of material with light-induced polymerization of resin, the process eliminates complex machinery, expensive consumables, and high energy consumption while achieving the required surface accuracy through digital light processing and diffuser-mediated uniform irradiance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If directional light is used in stereolithography, then the polymerization process is efficient, but defects like micro-bubbles and resin displacement occur due to light pressure

Engineering Contradiction:

Improvepolymerization efficiencyVSAvoiddefect-free production

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The diffuser acts as a mediator that transforms directional light into diffuse light while maintaining sufficient intensity for efficient polymerization. The scattered light distribution prevents micro-bubble formation and resin displacement caused by concentrated light pressure, while still enabling rapid curing of the resin layer by layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the spatial distribution parameter of the light field from directional to diffuse by introducing the diffuser. This parameter change maintains the total light energy available for polymerization (efficiency) while redistributing it uniformly across the resin surface to eliminate defect-forming localized high-intensity regions.

Inventive Principle:

Principle #35Parameter changes

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

The proposed solution significantly reduces scattering and diffraction effects, resulting in improved optical performance and homogeneity of 3D-printed lenses, making them more suitable for prescription eyewear by eliminating the need for semi-finished blanks and reducing energy consumption and waste.

Implementation Method 1

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 2

A UV light source with a wavelength of between 350nm and 420nm is used to polymerize each layer of an optical element

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 3

using transverse vibrations to minimize directional light effects, ensuring homogeneous irradiance and reducing defects

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Data Source

PatentEP3405330B1Creating homogeneous optical elements by additive manufacturing

Publication Date: 2021.08.18 INDIZEN OPTICAL TECHNOLOGIES OF AMERICA LLC

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AI summary

Systems and methods for additive manufacturing a homogeneous optical element are disclosed herein. A homogeneous pattern of light is shined on a polymerizable liquid to form each polymerized solid layer of the optical element.