TiO2-SiO2 Optical Glass Composition for High Refraction at Low Density
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Solution Overview
Problem
Existing high-refraction glasses used in augmented reality (AR) eyeglasses face issues such as increased density with rising refractive index, leading to discomfort due to weight, and are challenging to produce without crystallization and discoloration, while also being costly and difficult to process.
Innovation Solution
A TiO2- and SiO2-containing glass system with specific compositional ratios and low melting temperatures, achieving a refractive index above 1.85 and density below 4.5 g/cm³, ensuring stability and economic production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-refraction glass is used to increase field of view in AR eyeglasses, then the refractive index increases, but the density increases disproportionately causing increased weight and discomfort
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the glass system. Specifically, it uses a TiO2-SiO2-based system with controlled proportions of TiO2 (30-70 wt%), SiO2 (20-40 wt%), and other oxides to achieve a refractive index of nd>1.85 while maintaining density below 4.5 g/cm³. This compositional parameter optimization resolves the contradiction between high refraction and low weight.
Solution Approach 2:
The patent employs composite materials by creating a multi-component glass system combining TiO2, SiO2, B2O3, Al2O3, and various metal oxides in specific proportions. This composite approach allows the glass to achieve high refractive index through TiO2's optical properties while SiO2 and other components control the density and overall structure, thereby resolving the weight-refractive index contradiction.
2Illumination intensity
If niobium phosphate system or titanium phosphate system is used to achieve high refractive index, then the refractive index increases, but production becomes problematic due to oxygen loss, discoloration, and crystallization
Solution Approach 1:
The patent applies the extraction principle by removing P2O5 (phosphate) from the glass system, which is the source of production problems including oxygen loss, discoloration, and crystallization. The invention substitutes phosphate with oxide-based components (TiO2, SiO2, B2O3) that do not exhibit these problematic behaviors, thereby eliminating manufacturing difficulties while maintaining high refractive index.
Solution Approach 2:
The patent replaces expensive and problematic niobium phosphate or titanium phosphate systems with a more economical TiO2-SiO2-based system. This substitution uses readily available, cost-effective raw materials that are easier to process and do not require complex production controls, significantly improving ease of manufacture while achieving comparable or superior optical properties.
3Illumination intensity
If high lanthanum oxide content is used in lanthanum heavy flint systems to achieve high refractive index, then the refractive index increases, but the density increases and hardness increases causing longer grinding times and higher costs
Solution Approach 1:
The patent changes the compositional parameters by replacing lanthanum oxide (La2O3) with titanium dioxide (TiO2) as the primary high-refraction component. TiO2 provides high refractive index contribution without significantly increasing density or hardness to the same extent as lanthanum oxide. The controlled TiO2 content (30-70 wt%) achieves nd>1.85 while keeping the glass softer and easier to grind, thereby improving productivity.
4Weight of moving object
If high-refraction glass is made thinner to reduce weight for AR applications, then the weight decreases, but the glass becomes more brittle and difficult to polish
Solution Approach 1:
The patent uses composite materials to achieve a balanced glass system where TiO2 provides high refractive index for thin design, while SiO2 forms a robust glass network that provides mechanical strength and stability. The combination of TiO2 (30-70 wt%), SiO2 (20-40 wt%), and other oxides creates a composite structure that maintains adequate strength even when processed into thin wafers for AR applications, resolving the contradiction between weight reduction and mechanical stability.
Data Source
AI summary
An optical glass having a refractive index of more than 1.85, and glass articles comprising the optical glass, especially in the fields of optics and lenses, metaoptics and “augmented reality” (AR) are disclosed.