Bragg reflection optical device and methods for the manufacturing thereof
US6549254B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 3, 2000 |
| Grant date | Apr 15, 2003 |
| Priority date | — |
| Expiry date | Dec 29, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2201/343
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical device (20) is provided using at least one film (23) of cholesteric liquid crystal to reflect at least one predetermined wavelength band from an incident light. This device is characterized in that a non zero birefringence gradient is present in a portion or the entire thickness of said film. The gradient may be obtained in particular by superposing layers (24a-24j) having increasing or decreasing respective birefringence coefficients. The birefringence gradient has the effect of removing the lateral bands of the reflection spectrum, hence making the color of the reflected light more brilliant and more saturated. The effect is particularly advantageous in the case of the color red, for which the lateral band located on the yellow side is perceived strongly by the human eye.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.