Optical Glass Composition for Precision Press Molding
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Solution Overview
Problem
High-refractive-index, low-dispersion optical glasses used in precision press molding exhibit low glass stability, high glass transition temperature, and high liquidus temperature, leading to issues with crystal precipitation and striae generation during molding.
Innovation Solution
An optical glass composition with specific cation ratios and content percentages of Si4+, B3+, La3+, Gd3+, Zn2+, Ti4+, and W6+, optimized to achieve a refractive index of 1.89 or higher and an Abbé number of 28 to 36, with improved thermal stability and reduced glass transition temperature, preventing crystal precipitation and striae formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-refractive-index components (La2O3, Gd2O3, TiO2, WO3) are increased to achieve nd≥1.89 and vd=28-36, then optical performance is improved, but glass stability deteriorates and glass transition temperature increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of multiple oxide components. Specifically, it maintains B2O3 at 25-45%, ZnO at 10-40%, and limits TiO2 to 1-15% and WO3 to 1-20%, while controlling the ratio of high-refractive-index components (La2O3, Gd2O3) to ensure optical performance (nd≥1.89, vd=28-36) while preventing excessive glass transition temperature and maintaining glass stability during precision press molding.
Solution Approach 2:
The patent creates a composite glass system combining multiple oxide components with complementary functions: B2O3 and SiO2 provide glass network structure and stability, ZnO lowers glass transition temperature and improves moldability, La2O3 and Gd2O3 increase refractive index with low dispersion, and TiO2/WO3 further enhance refractive index. This composite approach achieves high optical performance while maintaining processing stability.
2Ease of manufacture
If glass transition temperature is lowered to improve precision press molding, then moldability is improved, but glass stability and resistance to crystal precipitation deteriorate
Solution Approach 1:
The patent achieves optimal glass transition temperature (below 630°C) by controlling the composition parameters, particularly maintaining B2O3 at 25-45% and ZnO at 10-40%, while limiting components that excessively raise glass transition temperature. This parameter optimization enables precision press molding at lower temperatures while maintaining glass stability and preventing crystal precipitation during the molding process.
Data Source
AI summary
The present invention relates to an optical glass with a refractive index nd of 1.89 or higher and an Abbé number v(nu)d of 28 to 36; a preform for precision press molding and an optical element that are comprised of this glass; and a method for manufacturing the optical element.