US7576791B2
Expired / Lapsed
US
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Method and apparatus for signature reduction using wavefront coding
Assignee: United States Department of the Army
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Filing: 2005-04-20
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Granted: 2009-08-18
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Expires: 2025-04-20
Abstract
Abstract The invention applies wavefront coding to the front of an electro-optic/infrared device to minimize the amount of light which is retroreflected by systems, such as Fowarding Looking Infrared systems, back to its source. The invention (unlike conventional reduction methods) does not rely on reducing the laser power leaving the interrogated sensor, but primarily on controlling its direction. A sensor according to the present invention, which has been wavefront coded for reduction of reflected light, will also effect the direction of the scattered light, thereby significantly reducing that which returns to the zero bistatic angle position. In contrast, a limitation of conventional methods is that once specular reflections are addressed, the remaining retroreflected signal typically results from scattered light at the focal plane which is largely collected and recollimated by the system optics.
Inventors
- 👤 Jaime Sonstroem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 03:15
CPC Classifications
G; G02; G02B; G02B23/00; G02B23/12; G02B13/00; G02B13/14; G02B13/16
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
78 words
A low-signature wavefront-coded electric-optic system comprising: at least one lens; a phase plate; a focal plane array; and a means to reconstruct an image wherein the phase plate has been specifically designed and positioned within the system such that light originating from an external source and entering the system, passes through the phase plate, reflects off the focal plane array, passes again through the phase plate and exits the system and is not retroreflected back to the source.
Claim 2
Dependent Claim
78 words
A low-signature wavefront-coded electric-optic system comprising: at least one lens; a phase plate; a focal plane array; and a means to reconstruct an image wherein the phase plate has been specifically designed and positioned within the system such that light originating from an external source and entering the system, passes through the phase plate, reflects off the focal plane array, passes again through the phase plate and exits the system and is not retroreflected back to the source.
Claim 3
Dependent Claim
16 words
The electric-optic system of claim 1 wherein the electric-optic system is a forward looking infrared device.
Claim 4
Dependent Claim
14 words
The electro-optic system of claim 1 wherein the electro-optic system is a TV camera.
Claim 5
Dependent Claim
14 words
The electro-optic system of claim 1 wherein the electro-optic system is an IITV camera.
Claim 6
Dependent Claim
26 words
electro-optic system of claim 1 comprising a second lens, the lens being placed in a telescope configuration and the phase plate is placed between the lenses.
Claim 7
Dependent Claim
29 words
The electro-optic system of claim 1 wherein wavefront coding as accomplished by the phase plate is tailored such that the retroreflected wavefront is minimal at a zero bistatic position.
Claim 8
Dependent Claim
21 words
The electro-optic system of claim 4 wherein the phase plate effects the direction of the scattered light of the retroreflected wavefront.
Claim 9
Dependent Claim
13 words
The electro-optic system of claim 1 wherein the focal plane array is uncooled.
Claim 10
Dependent Claim
18 words
The electro-optic system of claim 1 wherein the phase plate is placed at the pupil of the sensor.
Claim 11
Dependent Claim
15 words
The electro-optic system of claim 1 wherein the phase plate is part of the lens.
Claim 12
Dependent Claim
27 words
The electro-optic system of claim 1 wherein the phase plate is positioned so as to alter the direction of any retro-reflected signal emanating from the electro-optic system.
Claim 13
Independent Claim
77 words
A method of reducing a signature in an electro-optic system comprising the steps of: providing at least one lens; providing a phase plate; providing a focal plane array; and positioning the phase plate within the system such tat light originating from an external source and entering the system, passes through the phase plate, reflects off the focal plane array, passes again through the phase plate, and exits the system and is not retroreflected back to the source.
Claim 14
Independent Claim
77 words
A method of reducing a signature in an electro-optic system comprising the steps of: providing at least one lens; providing a phase plate; providing a focal plane array; and positioning the phase plate within the system such tat light originating from an external source and entering the system, passes through the phase plate, reflects off the focal plane array, passes again through the phase plate, and exits the system and is not retroreflected back to the source.
Claim 15
Dependent Claim
14 words
The method of claim 12 wherein electro-optic system is a forward looking infrared device.
Claim 16
Dependent Claim
27 words
The method of claim 12 comprising providing a second lens the lenses being placed in a telescoping configuration and the phase place is placed between the lenses.
Claim 17
Dependent Claim
28 words
The method of claim 12 wherein wavefront coding as accomplished by the phase plate is tailored such that the retroreflected wavefront is minimal at a zero bistatic position.
Claim 18
Dependent Claim
20 words
The method of claim 15 wherein the phase plate effects the direction of the scattered light of the retroreflected wavefront.
Claim 19
Dependent Claim
12 words
The method of claim 12 wherein the focal plane array is uncooled.
Claim 20
Dependent Claim
17 words
The method of claim 12 wherein the phase plate is placed at the pupil of the sensor.
Claim 21
Dependent Claim
14 words
The method of claim 12 wherein the phase plate is part of the lens.
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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) | 2012-08-17 | 2013-02-16 | 2013-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2016-08-17 | 2017-02-16 | 2017-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2020-08-17 | 2021-02-16 | 2021-08-18 | $7700.00 | Window Closed / Lapsed |