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US5148316A
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Averaged amplitude encoded phase-only filters for use in Fourier transform optical correlators
Assignee: United States Department of the Air Force
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Filing: 1991-04-30
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Granted: 1992-09-15
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Expires: 2011-04-30
Abstract
Abstract Method of producing an averaged amplitude mask, for use in conjunction with a phase only filter (pOF) to provide an averaged amplitude matched filter (AAMF) in a Fourier transform optical correlator, involves intensity normalizing a plurality of reference images within a given class of objects, averaging the intensities of the reference images, Fourier transforming the resulting data, and utilizing the resultant amplitude function, exclusive of phase, of the Fourier transform to produce the averaged amplitude filter. A number of such masks are sequentially positioned adjacent the POF to very rapidly determine whether an input image falls within a particular class of objects, or whether the input image is of a particular object within the class.
Inventors
- 👤 Joseph L. Horner
- 👤 Mary A. Flavin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:36
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; G06; G06V; G06V10/00; G06V10/88; G06V10/89; G06V10/893; G06V10/895
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
95 words
In an optical correlator having first Fourier transform means for producing the Fourier transform of an input image, at a Fourier transform filter plane; a phase only reference filter positioned within said Fourier transform plane and second Fourier transform means for producing a correlation response signal, the improvement comprising: an averaged amplitude mask optically co-acting with said phase only reference filter, said averaged amplitude mask representing the averaged amplitude of the Fourier transform, exclusive of phase, of a plurality of intensity normalized images within a homogenous class of images to be identified by said correlator.
Claim 2
Dependent Claim
95 words
In an optical correlator having first Fourier transform means for producing the Fourier transform of an input image, at a Fourier transform filter plane; a phase only reference filter positioned within said Fourier transform plane and second Fourier transform means for producing a correlation response signal, the improvement comprising: an averaged amplitude mask optically co-acting with said phase only reference filter, said averaged amplitude mask representing the averaged amplitude of the Fourier transform, exclusive of phase, of a plurality of intensity normalized images within a homogenous class of images to be identified by said correlator.
Claim 3
Dependent Claim
41 words
The optical correlator of claim 1 further including positioning means for sequentially positioning a plurality of said averaged amplitude masks adjacent said phase only reference filter, each of said masks representing a class of images to be identified by said correlator.
Claim 4
Dependent Claim
20 words
The optical correlator of claim 2 wherein said positioning means comprises a movable support member bearing said plurality of masks.
Claim 5
Dependent Claim
18 words
The optical correlator of claim 3 wherein said phase only reference filter is a binary phase only filter.
Claim 6
Dependent Claim
18 words
The optical correlator of claim 2 wherein said phase only reference filter is a binary phase only filter.
Claim 7
Dependent Claim
18 words
The optical correlator of claim 1 wherein said phase only reference filter is a vinary phase only filter.
Claim 8
Dependent Claim
94 words
In an optical correlator having first Fourier transform means for producing the Fourier transform of an input image, at a Fourier transform filter plane; a phase only reference filter positioned within said Fourier transform plane and second Fourier transform means for producing a correlation response signal the improvement comprising: an averaged amplitude mask positioned adjacent said phase only reference filter, said averaged amplitude mask representing the averaged amplitude of the Fourier transform, exclusive of phase, of a plurality of intensity normalized images within a homogenous class of images to be identified by said correlator.
Claim 9
Dependent Claim
94 words
In an optical correlator having first Fourier transform means for producing the Fourier transform of an input image, at a Fourier transform filter plane; a phase only reference filter positioned within said Fourier transform plane and second Fourier transform means for producing a correlation response signal the improvement comprising: an averaged amplitude mask positioned adjacent said phase only reference filter, said averaged amplitude mask representing the averaged amplitude of the Fourier transform, exclusive of phase, of a plurality of intensity normalized images within a homogenous class of images to be identified by said correlator.
Claim 10
Dependent Claim
41 words
The optical correlator of claim 9 further including positioning means for sequentially positioning a plurality of said averaged amplitude masks adjacent said phase only reference filter, each of said masks representing a class of images to be identified by said correlator.
Claim 11
Dependent Claim
20 words
The optical correlator of claim 10 wherein said positioning means comprises a rotatable support member bearing said plurality of masks.
Claim 12
Dependent Claim
18 words
The optical correlator of claim 9 wherein said phase only reference filter is a vinary phase only filter.
Claim 13
Dependent Claim
18 words
The optical correlator of claim 8 wherein said phase only reference filter is a vinary phase only filter.
Claim 14
Dependent Claim
18 words
The optical correlator of claim 7 wherein said phase only reference filter is a binary phase only filter.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-15 | 1996-03-16 | 1996-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-15 | 2000-03-16 | 2000-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-15 | 2004-03-16 | 2004-09-15 | $7700.00 | Window Closed / Lapsed |