US4198162A
Expired / Lapsed
US
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Tunable wide angular aperture filter by degenerate four-wave mixing
Assignee: AT&T Inc
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Filing: 1978-05-23
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Granted: 1980-04-15
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Expires: 1998-05-23
Abstract
Abstract A wide angular aperture, tunable filter device is achieved by using degenerate four-wave mixing. The apparatus utilizes two counter-propagating pump beams at substantially the same frequency to interact with an object beam, containing a spread of frequency components through a third order nonlinearity in the susceptibility of a medium. This produces a conjugate image beam formed with frequency components close to the frequency of the pump beams. By tuning the frequency of the pump beams the object beam frequency spectrum may be scanned while preserving all of the spatial information in the object beam. Apparatus for generating velocity contours of moving objects is also disclosed.
Inventors
- 👤 Gary C. Bjorklund
- 👤 David M. Bloom
- 👤 Paul F. Liao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:54
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/35; G02F1/353; G02F1/3536; G02F1/3538; G02F1/3534
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
137 words
A wide angular aperture wavelength tunable optical filter for extracting selected wavelength components from an input image beam comprising: a medium having a third order nonlinearity in susceptibility; a laser source of tunable radiation having a range of wavelengths which includes the wavelengths to be selected from said input image beam and directed such that its output radiation passes through said medium; a reflector positioned so as to retroreflect radiation from said laser source after the radiation has passed through the medium thereby establishing counterpropagating pump beams in said medium, said medium being oriented so as to receive said input image beam; and means positioned in the path of said input image beam to extract a conjugate image beam generated in said medium wherein said input image beam and said counterpropagating pump beams spatially and temporally overlap.
Claim 2
Dependent Claim
137 words
A wide angular aperture wavelength tunable optical filter for extracting selected wavelength components from an input image beam comprising: a medium having a third order nonlinearity in susceptibility; a laser source of tunable radiation having a range of wavelengths which includes the wavelengths to be selected from said input image beam and directed such that its output radiation passes through said medium; a reflector positioned so as to retroreflect radiation from said laser source after the radiation has passed through the medium thereby establishing counterpropagating pump beams in said medium, said medium being oriented so as to receive said input image beam; and means positioned in the path of said input image beam to extract a conjugate image beam generated in said medium wherein said input image beam and said counterpropagating pump beams spatially and temporally overlap.
Claim 3
Dependent Claim
20 words
An optical filter as defined in claim 1 wherein said means to extract a conjugate image beam is a beamsplitter.
Claim 4
Dependent Claim
39 words
An optical filter as defined in claim 1 wherein said filter further includes a quarter-wave plate positioned to intercept radiation between said reflector and said medium, and said means to extract a conjugate image beam is a polarizing beamsplitter.
Claim 5
Dependent Claim
16 words
A tunable optical filter as defined in claim 1 wherein said medium is CS 2 .
Claim 6
Dependent Claim
17 words
A tunable optical filter is defined in claim 1 wherein said medium is an atomic sodium vapor.
Claim 7
Dependent Claim
16 words
A tunable optical filter as defined in claim 1 wherein said medium is a ruby crystal.
Claim 8
Independent Claim
151 words
A device for obtaining a velocity contour of a moving object comprising: means for irradiating said moving object with a source beam of radiation having a source frequency; means for extracting a portion of said source beam; means for frequency modulating the portion of said source beam to form a modulated laser beam; means for generating substantially counterpropagating laser beams from said modulated laser beam; a medium having a third order nonlinearity in susceptibility positioned such that it is irradiated by said substantially counterpropagating laser beams; means for irradiating said medium with a probe beam of radiation obtained by reflection of said source beam from said moving object to form a conjugate image beam when said probe beam is substantially coincident spatially and temporally with said counterpropagating laser beams in said medium, said conjugate image beam containing a velocity contour of said moving object; means for detecting said conjugate image beam.
Claim 9
Independent Claim
151 words
A device for obtaining a velocity contour of a moving object comprising: means for irradiating said moving object with a source beam of radiation having a source frequency; means for extracting a portion of said source beam; means for frequency modulating the portion of said source beam to form a modulated laser beam; means for generating substantially counterpropagating laser beams from said modulated laser beam; a medium having a third order nonlinearity in susceptibility positioned such that it is irradiated by said substantially counterpropagating laser beams; means for irradiating said medium with a probe beam of radiation obtained by reflection of said source beam from said moving object to form a conjugate image beam when said probe beam is substantially coincident spatially and temporally with said counterpropagating laser beams in said medium, said conjugate image beam containing a velocity contour of said moving object; means for detecting said conjugate image beam.
Claim 10
Dependent Claim
42 words
A device for obtaining a velocity contour of a moving object as defined in claim 7 wherein said means for frequency modulating a portion of said source beam includes an electrooptical crystal, and means for applying a sinusoidal voltage to said crystal.
Claim 11
Dependent Claim
47 words
A device for obtaining a velocity contour of a moving object as defined in claim 7 wherein said means for frequency modulating a portion of said source beam comprises a transducer, a mirror affixed to said transducer, and means for applying a sinusoidal signal to said transducer.
Claim 12
Dependent Claim
23 words
A device for obtaining a velocity contour of a moving object as defined in claim 7 wherein said medium is CS 2 .
Claim 13
Dependent Claim
24 words
A device for obtaining a velocity contour of a moving object as defined in claim 7 wherein said medium is an atomic sodium vapor.
Claim 14
Dependent Claim
23 words
A device for obtaining a velocity contour of a moving object as defined in claim 7 wherein said medium is a ruby crystal.
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) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |