Patent US5561541A successfully refreshed from Google Patents.
US5561541A
Expired / Lapsed
US
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Frustrated total internal reflection optical power limiter
Assignee: United States Department of the Army
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Filing: 1984-09-05
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Granted: 1996-10-01
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Expires: 2004-09-05
Abstract
Abstract In order to protect a delicate photodetector from high-intensity radiation, such as from a laser, a device for limiting optical power to the detector is interposed between the radiation and the detector. This device has an optical interface that totally reflects high-intensity radiation, but which freely transmits normal (low intensity) radiation to the detector. The interface is between two optical materials, one with a linear index of refraction with respect to radiation intensity, and the other with a non-linear index. At low intensity radiation levels, the two materials have the same indices of refraction, and such radiation is freely transmitted through the interface, but with high-intensity radiation, a mismatch of indices of refraction allows total reflection at the interface.
Inventors
- 👤 Edward J. Sharp
- 👤 Gary L. Wood
- 👤 II Richard R. Shurtz
- 👤 Juergen L. W. Pohlmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:56
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/35; G02F1/3511; G02F1/01; G02F1/13; G02F1/132; G02F1/19; G02F1/195; G02B; G02B5/00; G02B5/20; G02B5/22
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
101 words
An optical power limiter for protecting a sensitive optical detector exposed to incident optical radiation, wherein said limiter includes: first and second materials with a planar interface therebetween at a total reflection angle for said incident radiation, whereby at least one of said materials is a nematic liquid crystal in its isotropic state and which has an index of refraction for said incident optical radiation dependent on the intensity of said optical radiation, wherein said limiter is transparent to optical radiation below a predetermined intensity threshold, but totally reflects, at said interface, optical radiation at or above said predetermined intensity threshold.
Claim 2
Dependent Claim
101 words
An optical power limiter for protecting a sensitive optical detector exposed to incident optical radiation, wherein said limiter includes: first and second materials with a planar interface therebetween at a total reflection angle for said incident radiation, whereby at least one of said materials is a nematic liquid crystal in its isotropic state and which has an index of refraction for said incident optical radiation dependent on the intensity of said optical radiation, wherein said limiter is transparent to optical radiation below a predetermined intensity threshold, but totally reflects, at said interface, optical radiation at or above said predetermined intensity threshold.
Claim 3
Dependent Claim
25 words
The limiter as set forth in claim 1 wherein both of said materials have indices of refraction dependent on the intensity of said optical radiation.
Claim 4
Dependent Claim
38 words
The limiter as set forth in claim 1 wherein said materials are encapulated in a container having transparent windows for entry and exit of said optical radiation, said windows having linear indices of refraction for said optical radiation.
Claim 5
Dependent Claim
20 words
The limiter as set forth in claim 3 additionally including an absorber on said container for absorbing totally reflected radiation.
Claim 6
Dependent Claim
22 words
The limiter as set forth in claim 3, additionally including heating means for said materials, whereby said intensity threshold may be varied.
Claim 7
Dependent Claim
22 words
The limiter as set forth in claim 4, additionally including heating means for said materials, whereby said intensity threshold may be varied.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-01 | 2000-04-01 | 2000-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-01 | 2004-04-01 | 2004-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-01 | 2008-04-01 | 2008-10-01 | $7700.00 | Window Closed / Lapsed |