Optical filter in the form of a rectangular parallelepiped having a plurality of nonintersecting bevels
US5071227A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 7, 1990 |
| Grant date | Dec 10, 1991 |
| Priority date | — |
| Expiry date | Dec 7, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09B19/0023
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An optical filter is formed as a rectangular parallelepiped having a plurality of beveled edges formed thereon, preferably three non-intersecting beveled edges formed at an angle of 45 degrees. The filter is formed of a clear, transparent, durable, shock-resistant material, preferably abrasion-resistant Lucite.TM. acrylic resin (trademark of the Du Pont Corporation) impregnated with a subtractive dye. The material has a refractive index closely matching that of glass, but is tougher and more shock resistant. The filter dimensions are in the ratio of small whole integers, specifically 2:3:4, for example, 1.times.1.5.times.2 inches. The beveled edges increase the residence time of light within the filter. By positioning differently colored filters of different orientations in optical series, many different hues may be produced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.