Patent EP0348141A1 successfully refreshed from Google Patents.
EP0348141A1
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Infrared filter using cholesteric liquids
Assignee: Rockwell Collins ElectroMechanical Systems Inc
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Filing: 1989-06-20
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Granted: —
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Expires: 2009-06-20
Abstract
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 (10) blocks infrared wavelengths beginning at a nearly visible corner wavelength and a cholesteric liquid crystal filter (12) 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 (15, 20) on a glass infrared filter element (10). 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.
Inventors
- 👤 Michael Kalmanash
- 👤 Arthur Louis Berman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 23:32
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/28; G02B5/281; G02B5/282; C; C09; C09K; C09K19/00; C09K19/04; C09K19/06; C09K19/08; C09K19/10; C09K19/22; C09K19/36; G02B5/30; G02B5/3016
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
33 words
A high precision wideband optical filter system characterised by: a wideband optical filter (10) having a first corner wavelength; and a cholesteric liquid crystal notch filter (12), said notch including said corner wavelength.
Claim 2
Dependent Claim
33 words
A high precision wideband optical filter system characterised by: a wideband optical filter (10) having a first corner wavelength; and a cholesteric liquid crystal notch filter (12), said notch including said corner wavelength.
Claim 3
Dependent Claim
27 words
An optical filter as claimed in claim 1, wherein said liquid crystal filter (12) comprises at least two films (15, 20) disposed on said wideband filter (10).
Claim 4
Dependent Claim
53 words
An infrared optical filter characterised by an infrared filter (10) for blocking transmission of light over a wide infrared band, said infrared filter having a nearly visible corner wavelength; and a cholesteric liquid crystal filter (12) for blocking transmission of infrared light in a narrow band, said narrow band including said corner wavelength.
Claim 5
Dependent Claim
53 words
An infrared optical filter characterised by an infrared filter (10) for blocking transmission of light over a wide infrared band, said infrared filter having a nearly visible corner wavelength; and a cholesteric liquid crystal filter (12) for blocking transmission of infrared light in a narrow band, said narrow band including said corner wavelength.
Claim 6
Dependent Claim
32 words
A filter as claimed in claim 3, wherein said liquid crystal filter includes an amount of nematic material chosen to maximize the reflectivity of said cholesteric filter substantially at said corner wavelength.
Claim 7
Dependent Claim
23 words
A filter as claimed in claim 3, wherein said cholesteric filter comprises two polymer films (15, 20) deposited on said infrared filter (10).
Claim 8
Dependent Claim
25 words
A filter as claimed in claim 1, wherein said cholesteric liquid crystal filter includes a nematic material for substantially determining the width of said notch.
Claim 9
Dependent Claim
27 words
A filter as claimed in claim 1, further including at least one additional cholesteric liquid crystal filter for blocking transmission of light in a second narrow band.
Claim 10
Dependent Claim
46 words
A night vision goggles assembly characterised by: a goggles frame (34), and an eyepiece (32) mounted in said frame (34), said eyepiece (32) including a visible light filter element (10) and a cholesteric liquid crystal filter element (12) disposed on said visible light filter element (10).
Claim 11
Dependent Claim
46 words
A night vision goggles assembly characterised by: a goggles frame (34), and an eyepiece (32) mounted in said frame (34), said eyepiece (32) including a visible light filter element (10) and a cholesteric liquid crystal filter element (12) disposed on said visible light filter element (10).
Claim 12
Dependent Claim
38 words
A night vision display system having a source of infrared light emissions, and an optical filter (2) for blocking said infrared emissions, said optical filter including a cholesteric liquid crystal notch filter element (12) disposed on said source.
Claim 13
Dependent Claim
38 words
A night vision display system having a source of infrared light emissions, and an optical filter (2) for blocking said infrared emissions, said optical filter including a cholesteric liquid crystal notch filter element (12) disposed on said source.
Claim 14
Independent Claim
70 words
A method of blocking the transmission of infrared light while transmitting visible light characterised by the steps of: providing a first infrared filter element (10); blocking infrared radiation above a nearly visible infrared corner wavelength with said first infrared filter element; providing a second, cholesteric liquid crystal filter element (12); and blocking infrared radiation in a band including said nearly visible corner wavelength using said cholesteric liquid crystal element (12).
Claim 15
Independent Claim
70 words
A method of blocking the transmission of infrared light while transmitting visible light characterised by the steps of: providing a first infrared filter element (10); blocking infrared radiation above a nearly visible infrared corner wavelength with said first infrared filter element; providing a second, cholesteric liquid crystal filter element (12); and blocking infrared radiation in a band including said nearly visible corner wavelength using said cholesteric liquid crystal element (12).
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