Infrared filter using cholesteric liquids
US5016985A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 24, 1988 |
| Grant date | May 21, 1991 |
| Priority date | — |
| Expiry date | Jun 24, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/3016
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A high precision optical filter includes a wideband filter element and a cholesteric liquid crystal notch filter element. In one embodiment, a wideband infrared filter blocks infrared wavelengths beginning at a nearly visible corner wavelength and a cholesteric liquid crystal filter blocks transmission of infrared wavelengths in a precise narrow band that includes the corner wavelength and that extends down to visible wavelengths. The liquid crystal filter may include a polymer for maintaining maximum reflectivity of the filter near the corner wavelength over an anticipated operating temperature range. The combined optical filter may be fabricated by depositing a matched pair of liquid crystal cholesteric films on a glass infrared filter element. In another embodiment, an optical filter according to the invention forms an eyepiece in a night vision goggles assembly for blocking visible light. The filter may also be mounted on a display device to block the transmission of undesirable infrared emissions at the source.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.