High strength ophthalmic lens
US3997250A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 2, 1975 |
| Grant date | Dec 14, 1976 |
| Priority date | — |
| Expiry date | Jul 2, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/315
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An ophthalmic glass lens having a compressively stressed surface zone after ion exchanging which is at least 60 micrometers in depth can be formed from an alkali metal oxide silicate glass comprising by weight about 4 to about 15 percent sodium oxide, about 3 to about 15 percent potassium oxide provided the total amount of sodium, potassium and other alkali metal oxides is up to about 20 percent and about 3 to about 15 percent lanthanum oxide. The ion exchange process can take place at a temperature either above or below the strain point of conventional ophthalmic crown glass to produce satisfactory physical properties in the ophthalmic glass lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.