Patent US5367579A successfully refreshed from Google Patents.
US5367579A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of removing spurious responses from optical joint transform correlators
Assignee: United States Department of the Air Force
•
Filing: 1993-06-25
•
Granted: 1994-11-22
•
Expires: 2013-06-25
Abstract
Abstract A joint transform optical correlator is disclosed having an optical path length adjustment technique for causing a first optical path length between the reference image plane and the first Fourier transform lens to differ from a second optical path length between the input image plane and the first Fourier transform lens by an amount whereby the second Fourier transform lens separates the desired cross-correlation signals from the undesired signals to enhance the performance and reliability of the correlator.
Inventors
- 👤 Bahram Javidi
- 👤 Qing Tang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:30
CPC Classifications
G; G06; G06E; G06E3/00; G06E3/001; G06E3/003; G06V; G06V10/00; G06V10/88; G06V10/92
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
179 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference image plane and an input image at an input image plane; (b) first Fourier transform means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) detector means for detecting said interference pattern and for outputting a Fourier transform interference intensity distribution signal; (d) a second Fourier transform means for inverse Fourier transforming said interference intensity distribution signal; (e) and further including optical path length adjustment means for causing a first optical path length between said reference image plane and said first Fourier transform means to differ from a second optical path length between said input image plane and said first Fourier transform means by an amount whereby said second Fourier transform means produces a first off-axis cross-correlation function signal in a first plane and a second off-axis cross-correlation function signal in a second plane separated from said first plane.
Claim 2
Dependent Claim
179 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference image plane and an input image at an input image plane; (b) first Fourier transform means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) detector means for detecting said interference pattern and for outputting a Fourier transform interference intensity distribution signal; (d) a second Fourier transform means for inverse Fourier transforming said interference intensity distribution signal; (e) and further including optical path length adjustment means for causing a first optical path length between said reference image plane and said first Fourier transform means to differ from a second optical path length between said input image plane and said first Fourier transform means by an amount whereby said second Fourier transform means produces a first off-axis cross-correlation function signal in a first plane and a second off-axis cross-correlation function signal in a second plane separated from said first plane.
Claim 3
Dependent Claim
42 words
The correlator of claim 1 wherein said optical path length adjustment means comprises a single transparent optical element having an index of refraction greater than one and positioned to intercept light from only one image produced by said joint image production means.
Claim 4
Dependent Claim
14 words
The correlator of claim 2 wherein said transparent optical element comprises a rectangular block.
Claim 5
Dependent Claim
16 words
The correlator of claim 1 wherein said detector means comprises a nonlinear liquid crystal light valve.
Claim 6
Dependent Claim
16 words
The correlator of claim 2 wherein said detector means comprises a nonlinear liquid crystal light valve.
Claim 7
Dependent Claim
16 words
The correlator of claim 3 wherein said detector means comprises a nonlinear liquid crystal light valve.
Claim 8
Dependent Claim
204 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference input plane and an input image at an input image plane; (b) a first Fourier transform lens means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) an image energy detector located at a Fourier plane for receiving said interference pattern and for outputting a light pattern comprising a Fourier transform interference intensity signal; (d) a second Fourier transform lens means for receiving said light pattern from said image energy detector and for inverse Fourier transforming said light pattern; (e) and further including optical path length adjustment means for causing a first optical path length between a reference image plane and said first Fourier transform lens means to differ from a second optical path length between an input image plane and said first Fourier transform lens means by an amount whereby said second Fourier transform lens means focuses a first off-axis cross-correlation function signal in a first plane and a second off-axis cross-correlation function signal in a second plane separated from said first plane.
Claim 9
Dependent Claim
204 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference input plane and an input image at an input image plane; (b) a first Fourier transform lens means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) an image energy detector located at a Fourier plane for receiving said interference pattern and for outputting a light pattern comprising a Fourier transform interference intensity signal; (d) a second Fourier transform lens means for receiving said light pattern from said image energy detector and for inverse Fourier transforming said light pattern; (e) and further including optical path length adjustment means for causing a first optical path length between a reference image plane and said first Fourier transform lens means to differ from a second optical path length between an input image plane and said first Fourier transform lens means by an amount whereby said second Fourier transform lens means focuses a first off-axis cross-correlation function signal in a first plane and a second off-axis cross-correlation function signal in a second plane separated from said first plane.
Claim 10
Dependent Claim
42 words
The correlator of claim 7 wherein said optical path length adjustment means comprises a single transparent optical element having an index of refraction greater than one and positioned to intercept light from only one image produced by said joint image production means.
Claim 11
Dependent Claim
14 words
The correlator of claim 8 wherein said transparent optical element comprises a rectangular block.
Claim 12
Dependent Claim
16 words
The correlator of claim 7 wherein said energy detector comprises a nonlinear liquid crystal light valve.
Claim 13
Dependent Claim
16 words
The correlator of claim 8 wherein said energy detector comprises a nonlinear liquid crystal light valve.
Claim 14
Dependent Claim
16 words
The correlator of claim 9 wherein said energy detector comprises a nonlinear liquid crystal light valve.
Claim 15
Dependent Claim
192 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference input plane and an input image at an input image plane; (b) a first Fourier transform lens means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) a nonlinear thresholded image detector for receiving said interference pattern and for outputting a binary Fourier transform interference intensity distribution signal; (d) a second Fourier transform lens means for inverse Fourier transforming said binary Fourier transform interference intensity distribution signal; (e) and further including optical path length adjustment means for causing a first optical path length between a reference image plane and said first Fourier transform lens means to differ from a second optical path length between an input image plane and said first Fourier transform lens means by an amount whereby said second Fourier transform lens means focuses a first off-axis cross-correlation peak signal in a first plane and a second off-axis cross-correlation peak signal in a second plane separated from said first plane.
Claim 16
Dependent Claim
192 words
A joint transform correlator for producing a plurality of joint transform image cross-correlation signals comprising: (a) joint image production means for producing a joint image of a reference image at a reference input plane and an input image at an input image plane; (b) a first Fourier transform lens means for producing an interference pattern between Fourier transforms of said reference image and said input image; (c) a nonlinear thresholded image detector for receiving said interference pattern and for outputting a binary Fourier transform interference intensity distribution signal; (d) a second Fourier transform lens means for inverse Fourier transforming said binary Fourier transform interference intensity distribution signal; (e) and further including optical path length adjustment means for causing a first optical path length between a reference image plane and said first Fourier transform lens means to differ from a second optical path length between an input image plane and said first Fourier transform lens means by an amount whereby said second Fourier transform lens means focuses a first off-axis cross-correlation peak signal in a first plane and a second off-axis cross-correlation peak signal in a second plane separated from said first plane.
Claim 17
Dependent Claim
42 words
The correlator of claim 13 wherein said optical path length adjustment means comprises a single transparent optical element having an index of refraction greater than one and positioned to intercept light from only one image produced by said joint image production means.
Claim 18
Dependent Claim
14 words
The correlator of claim 14 wherein said transparent optical element comprises a rectangular block.
Claim 19
Dependent Claim
18 words
The correlator of claim 13 wherein said nonlinear thresholded image detector comprises a nonlinear liquid crystal light valve.
Claim 20
Dependent Claim
18 words
The correlator of claim 14 wherein said nonlinear thresholded image detector comprises a nonlinear liquid crystal light valve.
Claim 21
Dependent Claim
18 words
The correlator of claim 15 wherein said nonlinear threshold image detector comprises a nonlinear liquid crystal light valve.
Claim 22
Dependent Claim
17 words
The correlator of claim 2 wherein said joint image production means comprises a single spatial light modulator.
Claim 23
Dependent Claim
17 words
The correlator of claim 3 wherein said joint image production means comprises a single spatial light modulator.
Claim 24
Dependent Claim
17 words
The correlator of claim 14 wherein said joint image production means comprises a single spatial light modulator.
Claim 25
Dependent Claim
17 words
The correlator of claim 15 wherein said joint image production means comprises a single spatial light modulator.
References Cited (Backward Citations)
US4084255A
Cited
US4204262A
Cited
US4723125A
Cited
US4831598A
Cited
US4826285A
Cited
US4832447A
Cited
US4922256A
Cited
US5119443A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-11-21 | 1998-05-23 | 1998-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-21 | 2002-05-23 | 2002-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-21 | 2006-05-23 | 2006-11-22 | $7700.00 | Window Closed / Lapsed |