Optical Glass Composition for High Refractive Index and Low Dispersion
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Solution Overview
Problem
High-refractivity and low-dispersion optical glasses with refractive index greater than 1.86 and Abbe number greater than 38.8 are difficult to produce due to issues with devitrification, high cost, and manufacturing challenges, particularly with excessive lanthanide oxides affecting glass forming ability.
Innovation Solution
An optical glass composition comprising specific weight percentages of B2O3, La2O3, Gd2O3, SiO2, ZrO2, TiO2, WO3, Ta2O5, ZnO, and Nb2O5, with controlled ratios to achieve high refractivity and low dispersion, while minimizing devitrification and production costs, including the use of reduced Ta2O5 content to maintain low dispersion and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If excessive lanthanide oxides are introduced to improve refractive index, then refractive index increases, but glass forming ability deteriorates and manufacturing difficulty increases
Solution Approach 1:
The patent changes the chemical composition parameters by limiting lanthanide oxide content to 60-80 wt% and introducing specific amounts of TiO2 (2-10 wt%), WO3 (2-10 wt%), and Nb2O5 (2-10 wt%). This parameter optimization resolves the contradiction by achieving refractive index ≥1.86 while maintaining glass forming ability through balanced composition.
Solution Approach 2:
The patent creates a composite glass system combining multiple oxide components (La2O3, Gd2O3, TiO2, WO3, Nb2O5, B2O3, SiO2) in specific ratios. This composite approach allows the glass to achieve high refractive index through synergistic effects while maintaining manufacturability through balanced composition.
2Illumination intensity
If traditional high-refractive index glass composition is used, then refractive index is improved, but devitrification resistance deteriorates
Solution Approach 1:
The patent optimizes composition parameters including B2O3 (10-30 wt%), SiO2 (5-20 wt%), and limits Ta2O5 to 0.1-5 wt% while controlling the ratio m(B2O3+SiO2+ZrO2+Nb2O5+TiO2+WO3)/m(La2O3+ZrO2) ≥0.6. These parameter changes achieve refractive index ≥1.86 while suppressing devitrification through balanced network formation and crystal growth inhibition.
Data Source
AI summary
Disclosed are an optical glass, a glass preform, an optical element and an optical instrument having the same. The optical glass comprises 5 to 25 wt % of B2O3, 25 to 45 wt % of La2O3, 0 to 10 Wt % of Y2O3, 10 to 35 wt % of Gd2O3, 0.5 to 15 wt % of SiO2, 1 to 15 wt % of ZrO2, 0 to 5 wt % of TiO2, 0 to 7 wt % of WO3, 0 to 15 wt % of Ta2O5, 0 to 10 wt % of ZnO and 0 to 8.5 wt % of Nb2O5; and m(B2O3+SiO2+ZrO2+Nb2O5+TiO2+WO3)/m(La2O3+ZrO2) is not lower than 0.6.