Ophthalmic filter materials
US5973865A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1998 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Sep 29, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/102
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An ophthalmic filter material having a photopic transmittance (Y.sub.P) higher than the scotopic transmittance (Y.sub.S), the ratio of Y.sub.P :Y.sub.S being in the range of 2.0-4.0, a dominant wavelength within the ranges of 580-605 nm and a color purity of 60-75% whereby colors perceived through the material approximate those of the scene being viewed. A method of producing such a filter material which comprises heating a photochromic glass lens in a reducing atmosphere for a time and at a temperature that is sufficient to impart the recited characteristics to the glass surface and that is equivalent to a flowing hydrogen atmosphere, or immersing a tintable plastic solution in a dye solution for a time sufficient to impart the recited characteristics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.