Optical Glass Composition for Stable Precision Press-Molding
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Solution Overview
Problem
High-refractivity low-dispersion optical glasses used in precision press-molding face issues with surface fogging and breakage due to reactions between high-refractivity-imparting components like Ti and W with press mold materials, leading to poor product quality.
Innovation Solution
An optical glass composition with specific cationic ratios of B3+, Si4+, La3+, Gd3+, Y3+, Ti4+, Nb5+, Ta5+, W6+, and Zn2+, optimized to maintain thermal stability and prevent redox reactions with press molds, with a refractive index of 1.89 or more and an Abbe's number of 27 to 37, allowing for stable precision press-molding of high-quality optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-refractivity-imparting components such as Ti and W are introduced to achieve higher refractivity, then the refractive index increases, but redox reactions occur with press mold materials causing surface fogging and breakage
Solution Approach 1:
The patent changes the chemical composition parameters by limiting Ti4+ to 0-4% and W6+ to 0-5%, and specifically controlling the ratio of (Nb5++Ta5+)/(Ti4++Nb5++Ta5++W6+) to be 0.7 to 1.0. This parameter optimization reduces redox reactions with press molds while maintaining high refractivity (nd≥1.89) and low dispersion (νd=27-37), thereby improving press-molding stability without sacrificing optical performance
Solution Approach 2:
The patent introduces Nb5+ and Ta5+ as intermediary components that can impart high refractivity without causing severe redox reactions with press mold materials. These intermediaries partially replace Ti4+ and W6+, providing a compromise solution that maintains high refractive index while reducing harmful chemical reactions during precision press-molding
2Stability of the object's composition
If rare earth components such as La are introduced to achieve lower dispersion, then the Abbe's number increases, but the glass composition becomes more complex and harder to control
Solution Approach 1:
The patent combines multiple rare earth components (La3+, Gd3+, Y3+, Yb3+) with high-refractivity components (Nb5+, Ta5+, Ti4+, W6+) in a unified glass system. By merging these components and controlling their interactions, the patent achieves both low dispersion (νd=27-37) and high refractivity (nd≥1.89) while managing composition complexity through defined concentration ranges and ratios
3Productivity
If precision press-molding is repeated multiple times, then productivity increases, but glass fuses to the molding surface and product quality deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by optimizing the glass composition before press-molding to prevent adhesion to mold surfaces. By controlling the content of high-refractivity components (Ti4+≤4%, W6+≤5%) and adjusting the ratio of (Nb5++Ta5+)/(Ti4++Nb5++Ta5++W6+) to 0.7-1.0, the glass exhibits reduced chemical reactivity with mold materials, preventing surface fogging and enabling repeated press-molding cycles without quality deterioration
Data Source
AI summary
[Problems to be Solved]To provide a high-refractivity low-dispersion optical glass that enables the stable production of high-quality optical elements.[Means to Solve the Problems]An optical glass comprising, as essential components,20 to 50% of B3+,5 to 35% of La3+,1 to 30% of Nb5+,0.5 to 15% of Ta5+, and11 to 40% of Zn2+,the total content of B3+ and Si4+ being 20 to 50%, the total content of La3+, Gd3+ and Y3+ being 5 to 35%, the cationic ratio of ((B3++Si4+)/(La3++Gd3++Y3+)) being from 1 to 5, the total content of Ti4+, Nb5+, Ta5+ and W6+ being 10 to 35%, the cationic ratio of ((Nb5++Ta5+)/(Ti4++Nb5++Ta5++W6+)) being from 0.7 to 1, the cationic ratio of ((B3++Si4+)/(Ti4++Nb5++Ta5++W6+)) being from 0.5 to 4, the cationic ratio of ((La3++Gd3++Y3+)/(Ti4++Nb5++Ta5++W6+)) being from 0.2 to 3, the cationic ratio of Zn2+/Zn2++Mg2++Ca2++Sr2++Ba2+) being from 0.8 to 1, the optical glass having a refractive index nd of 1.89 or more and an Abbe's number νd of 27 to 37.