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US4110016A
Expired / Lapsed
US
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Acousto-optic real time correlator
Assignee: United States Department of the Army
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Filing: 1977-06-07
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Granted: 1978-08-29
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Expires: 1997-06-07
Abstract
Abstract An acousto-optic correlator device comprised of two parallel piezoelectricrystals having different acoustic velocities. Acoustic transducers are located at one end of the respective crystals, and high frequency acoustic waves, the pulse envelopes of which correspond to the signals to be correlated are simultaneously launched from the transducers on the respective crystals. One of the acoustic waves "slides" past the other, and a laser beam, which is directed approximately perpendicular to the direction of acoustic propagation is modulated by the acoustic waves. The laser beam is demodulated and the desired correlation is obtained.
Inventors
- 👤 Norman J. Berg
- 👤 Bob L. Smith, deceased
- 👤 legal representative by Allen B. Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:20
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/11; G06; G06E; G06E3/00; G06E3/001; G06E3/005
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
136 words
An acousto-optic apparatus for providing the correlation of first and second electrical signals without the necessity of time inversion, comprising first and second acousto-optic interaction media disposed adjacent each other, said second interaction medium having a lower acoustic velocity than said first medium, each of said media having an acoustic transducer means disposed thereon, means for applying a high frequency A.C. signal to said transducer means on said first medium, the envelope of which corresponds to said first electrical signal, means for applying a high frequency A.C. signal to said transducer means on said second medium, the envelope of which corresponds to said second electrical signal, laser means directed to transmit a laser beam across both said media, and detector means for detecting said laser beam after it traverses said first and second acousto-optic interaction media.
Claim 2
Dependent Claim
136 words
An acousto-optic apparatus for providing the correlation of first and second electrical signals without the necessity of time inversion, comprising first and second acousto-optic interaction media disposed adjacent each other, said second interaction medium having a lower acoustic velocity than said first medium, each of said media having an acoustic transducer means disposed thereon, means for applying a high frequency A.C. signal to said transducer means on said first medium, the envelope of which corresponds to said first electrical signal, means for applying a high frequency A.C. signal to said transducer means on said second medium, the envelope of which corresponds to said second electrical signal, laser means directed to transmit a laser beam across both said media, and detector means for detecting said laser beam after it traverses said first and second acousto-optic interaction media.
Claim 3
Dependent Claim
93 words
The apparatus of claim 1 wherein said first and second acousto-optic interaction media are first and second piezoelectric crystals each having a long dimension, said crystals being disposed so that the long dimensions of the respective crystals are parallel to each other, said acoustic transducer means being disposed adjacent one end of said crystals, and being oriented so that the acoustic waves generated thereby are propagated approximately parallel to said long dimensions, said laser means being arranged so that said laser beam is directed across said crystals approximately perpendicular to said long dimensions.
Claim 4
Dependent Claim
63 words
The apparatus of claim 2 wherein the acousto-optic velocity of said second crystal is a given fraction of the acousto-optic velocity of said first crystal, and wherein the A.C. frequency of the signal applied to the transducer means on said second crystal is said same given fraction of the A.C. frequency of the signal applied to the transducer means on said first crystal.
Claim 5
Dependent Claim
118 words
The apparatus of claim 3 wherein each of said acoustic transducer means comprises a plurality of acoustic transducers, each of said transducers being oriented at a very small angle with respect to the adjacent transducer so that the acoustic waves generated thereby are in the direction of said long dimension or at very small angles displaced therefrom, each transducer being adapted for the application of a signal of different A.C. frequency, and said very small angles being the corresponding Bragg angles for the respective frequencies and being determined according to the relationship θ.sub.B = λ.sub.o /2n λ.sub.a where θ B = Bragg angle λ o = optical wavelength n = index of refraction λ a = acoustic wavelength
Claim 6
Dependent Claim
26 words
The apparatus of claim 1 wherein said first interaction medium is a lithium niobate crystal and said second interaction medium is a bismuth germanium oxide crystal.
References Cited (Backward Citations)
US4012120A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-08-28 | 1982-02-27 | 1982-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-28 | 1986-02-27 | 1986-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-28 | 1990-02-27 | 1990-08-29 | $7700.00 | Window Closed / Lapsed |