Low-Density High-Refraction Glass Composition for AR Optics
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Solution Overview
Problem
Existing high-refraction glasses used in augmented reality (AR) eyeglasses face issues such as increased density leading to weight, production challenges like crystallization and coloration, and difficulty in processing due to high melting temperatures, which affect comfort and efficiency.
Innovation Solution
A glass composition with a refractive index above 1.95 and density below 4.5 g/cm³, comprising SiO₂, TiO₂, and Nb₂O₅, with controlled ratios of other components to minimize crystallization and coloration, allowing for lower melting temperatures and improved processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-refraction glass is used to increase field of view in AR eyeglasses, then optical performance is improved, but density increases leading to excessive weight and discomfort
Solution Approach 1:
The patent changes the chemical composition parameters of the glass, specifically using a silicate system with TiO2 (15-40 wt%) and Nb2O5 (5-20 wt%) to achieve high refractive index (nd>1.95) while controlling density (ρ<4.5 g/cm³). This parameter optimization allows thin wafer design for AR applications without excessive weight
Solution Approach 2:
The patent creates a composite glass system combining multiple oxides (SiO2, TiO2, Nb2O5, ZnO, B2O3, Al2O3, and rare earth oxides) to achieve a balance between high refractive index and low density. The composite composition enables optical performance comparable to heavy flint glasses without the associated weight penalty
2Illumination intensity
If niobium phosphate system glasses are used to achieve high refractive index, then optical properties are improved, but production becomes problematic due to oxygen loss and coloration
Solution Approach 1:
The patent extracts the problematic phosphate system and replaces it with a silicate-based system. By removing P2O5 from the composition and using SiO2 as the primary glass former, the patent eliminates the reducing atmosphere requirements and oxygen loss issues inherent to phosphate systems, enabling production in conventional oxidizing atmospheres
Solution Approach 2:
The patent uses a composition that allows for simpler, more robust manufacturing processes. The silicate system with controlled TiO2 and Nb2O5 content enables melting in standard equipment without requiring specialized reducing atmosphere control, making the production process more accessible and less costly
3Illumination intensity
If titanium and niobium contents are increased to achieve high refractive index, then optical performance is improved, but tendency to crystallization increases significantly
Solution Approach 1:
The patent optimizes the ratio and content of TiO2 (15-40 wt%) and Nb2O5 (5-20 wt%) to achieve high refractive index while suppressing crystallization. The specific composition range, combined with SiO2 (30-60 wt%) as a stabilizing glass former, prevents the formation of crystalline phases during melting and cooling processes
Solution Approach 2:
The patent uses ZnO (0.1-10 wt%) and B2O3 (0.1-10 wt%) as intermediary components that modify the glass structure to suppress crystallization. These oxides act as network modifiers that disrupt the formation of crystalline TiO2 and Nb2O5 phases while maintaining the high refractive index properties
4Illumination intensity
If high melting and refining temperatures are used to process high-refraction glass, then optical properties are improved, but weight loss due to oxygen loss occurs
Solution Approach 1:
The patent changes the chemical composition to a silicate system that is stable in oxidizing atmospheres at high temperatures. The SiO2-based network with TiO2 and Nb2O5 as high-index components maintains compositional stability during melting and refining, preventing oxygen loss and associated weight reduction that plagues phosphate systems
5Illumination intensity
If lanthanum oxide content is increased to achieve high refractive index, then optical properties are improved, but density and hardness increase leading to higher costs
Solution Approach 1:
The patent changes the approach to achieving high refractive index by using TiO2 and Nb2O5 in a silicate system rather than relying on high lanthanum oxide content. This alternative composition achieves nd>1.95 with density<4.5 g/cm³, avoiding the high density and hardness associated with lanthanum-heavy flint glasses
Data Source
AI summary
The invention relates to an optical glass having a refractive index of more than 1.95, to glass articles including the optical glass and to the use thereof, especially in the fields of optics and lenses, metaoptics and augmented reality (AR).