Infrared filter using cholesteric liquids
First Claim
1. A high precision wideband optical filter system comprising:
- a wideband optical filter having a corner wavelength; and
a cholesteric liquid crystal notch filter, said notch including said corner wavelength.
1 Assignment
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Accused Products
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.
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Citations
13 Claims
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1. A high precision wideband optical filter system comprising:
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a wideband optical filter having a corner wavelength; and a cholesteric liquid crystal notch filter, said notch including said corner wavelength. - View Dependent Claims (2, 3, 4, 5, 7)
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6. An infrared optical filter comprising:
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an infrared filter 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 for blocking transmission of infrared light in a narrow band, said narrow band including said corner wavelength. - View Dependent Claims (8, 9)
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10. A night vision goggles assembly comprising:
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a goggles frame; and an eyepiece mounted in said frame, said eyepiece including a visible light filter element and a cholesteric liquid crystal filter element disposed on said visible light filter element.
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11. An eyepiece including:
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a supporting optical element forming a wideband filter element; at least two cholesteric liquid crystal films, forming a notch filter, disposed on the supporting optical element.
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12. A high precision, wideband optical filter system for filtering radiation from a source emitting both visible and infrared radiation, the infrared radiation including a near visible infrared radiation peak, comprising:
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a wideband, infrared filter having a corner wavelength between a maximum visible radiation peak from the source and the near infrared peak; and notch filter means, including a cholesteric filter element, having a notch which includes said corner wavelength.
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13. A method of blocking the transmission of infrared light while transmitting visible light including the steps of:
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providing a first infrared filter element; blocking infrared radiation above a nearly visible infrared corner wavelength with said first infrared filter element; providing a second cholesteric liquid crystal filter element; and blocking infrared radiation in a band including said nearly visible corner wavelength using said cholesteric liquid crystal element.
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Specification