Ophthalmic and optical glass
US4732876A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 28, 1987 |
| Grant date | Mar 22, 1988 |
| Priority date | — |
| Expiry date | May 28, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S501/903
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An Ophthalmic and optical glass which is a B.sub.2 O.sub.3 - SiO.sub.2 - Li.sub.2 O - CaO - La.sub.2 O.sub.3 - TiO.sub.2 - ZrO.sub.2 -Nb.sub.2 O.sub.5 system in which relatively large amounts of B.sub.2 O.sub.3 and La.sub.2 O.sub.3 ingredients coexist has improved resistivity to devitrification while maintaining desirable optical constants, i.e., a refractive index (.eta.d) in the range of 1.75 to 1.84, Abbe number (.nu.d) in the range of 33 to 40 and specific gravity of 4.0 or less. Besides, the range of content of the Li.sub.2 O ingredient which is effective for the chemical strengthening treatment can be enlarged by this system of glass.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.