Protective filter lenses
US5381193A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 1993 |
| Grant date | Jan 10, 1995 |
| Priority date | — |
| Expiry date | Feb 22, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/102
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An ophthalmic protective filter lens having a scotopic transmittance lower than the photopic transmittance by more than a factor of two, a dominant wavelength within the ranges of 580-605 nm and a color purity of 75-85 whereby colors perceived through the lens are approximately those of the scene being viewed. A method of producing an ophthalmic protective filter lens which comprises firing a photochromic glass lens in a hydrogen-containing atmosphere within the temperature range of 400.degree.-430.degree. C. for a time of 1-8 hours to impart a scotopic transmittance lower than the photopic transmittance by a factor of at least two, a dominant wavelength within the ranges of 580-605 nm and a color purity of 75-85 whereby colors perceived through the lens are approximately those of the scene.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.