Directional optical filter
US4621898A · kind A · utility
130Cited by
3References
17Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 17, 1983 |
| Grant date | Nov 11, 1986 |
| Priority date | — |
| Expiry date | Mar 17, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A directional filter is constructed with a plurality of grooves (15) extending into a plate (13) from one side (16) thereof. The grooves (15) have a light absorbing characteristic which causes them to absorb light impinging upon the grooves, particularly light impinging upon the grooves (15) from within the plate (13). Since all light passing beyond a certain angle .phi. must impinge upon the grooves (13), and only a small percentage of light passing parallel to the cut of the grooves (15) would impinge upon the grooves (15), the filter has a high ratio of attenuation of unwanted versus wanted light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.