Multilayer optical filter for producing colored reflected light and neutral transmission
US4793669A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 11, 1987 |
| Grant date | Dec 27, 1988 |
| Priority date | — |
| Expiry date | Sep 11, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/108
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A short-wave-pass optical filter, that includes a partially absorbing or transparent substrate coated by a set of layers having specified quarter-wave optical thickness, and is designed to reflect visible radiation of a selected color while transmitting visible radiation and maintaining a neutral color balance. The coating includes layers having a high refractive index alternating with layers having a low refractive index. The refractive indices and layer thicknesses are selected so that the filter's reflectance spectrum exhibits a ripple over a first segment of the visible spectrum but no significant ripple over a second segment of the visible. The filters may be used as sunglass lenses that have a selected color (such as blue, orange, or violet) when viewed by one other than the sunglass wearer, while permitting the wearer to perceive transmitted light with a correct color balance. The design of the inventive filter is preferably optimized to have the desired optical properties while being conveniently and repeatably manufacturable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.