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US4118113A
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Second order birefringent acousto-optic device
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1976-11-05
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Granted: 1978-10-03
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Expires: 1996-11-05
Abstract
Abstract An acousto-optic deflector that utilizes second order diffraction in a birefringent crystal provides doubled resolution while maintaining high diffraction efficiency. For the second order birefringent deflector employing a paratellurite crystal, 1200 spot resolution was achieved with a 24 MHz bandwidth and 25 μ sec access time. This maximum number of spots is twice that obtainable in a conventional first order acousto-optic deflector.
Inventors
- 👤 I-Cheng Chang
- 👤 David L. Hecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:33
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/33
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
116 words
A second order acousto-optic device comprising a birefringent medium, means for generating and propagating acoustic waves in the said medium for providing nearly degenerate phase matching for first and second diffraction orders over a total scanning frequency bandwidth Δf, and an acoustic transit time τ, across the optical aperture of said medium, means for directing a laser beam through said medium to be diffracted by said acoustic waves, means for selecting the mid-band acoustic frequency of the said acoustic waves to achieve degenerate phase matching for deflecting the said beam into the second order with high efficiency, and means for utilization of said second order beam to provide doubled resolution, 2Δfτ, while maintaining high diffraction efficiency.
Claim 2
Dependent Claim
116 words
A second order acousto-optic device comprising a birefringent medium, means for generating and propagating acoustic waves in the said medium for providing nearly degenerate phase matching for first and second diffraction orders over a total scanning frequency bandwidth Δf, and an acoustic transit time τ, across the optical aperture of said medium, means for directing a laser beam through said medium to be diffracted by said acoustic waves, means for selecting the mid-band acoustic frequency of the said acoustic waves to achieve degenerate phase matching for deflecting the said beam into the second order with high efficiency, and means for utilization of said second order beam to provide doubled resolution, 2Δfτ, while maintaining high diffraction efficiency.
Claim 3
Dependent Claim
35 words
A device as recited in claim 1 wherein the said midband acoustic frequency is selected by choosing the incident angle of the said laser beam with respect to the optic axis of the said medium.
Claim 4
Dependent Claim
51 words
A device as recited in claim 1 wherein the said medium comprises a TeO 2 crystal, and wherein the acoustic waves are propagated in the [110] direction of the said TeO 2 crystal and the said laser beam is incident close to the optic axis of the said TeO 2 crystal.
Claim 5
Dependent Claim
87 words
In an acousto-optic deflector, a method for achieving doubled resolution while maintaining high diffraction efficiency by utilizing second order acousto-optic diffraction in a birefringent crystal comprising: (a) propagating acoustic waves in said crystal; (b) directing a laser beam through said crystal to be diffracted by said acoustic waves; and, (c) selecting the mid-band frequency of the said acoustic waves to achieve degenerate phase matching for deflecting said beam into the second order, and (d) using said second order diffracted beam as the output of said acousto-optic deflector.
Claim 6
Dependent Claim
87 words
In an acousto-optic deflector, a method for achieving doubled resolution while maintaining high diffraction efficiency by utilizing second order acousto-optic diffraction in a birefringent crystal comprising: (a) propagating acoustic waves in said crystal; (b) directing a laser beam through said crystal to be diffracted by said acoustic waves; and, (c) selecting the mid-band frequency of the said acoustic waves to achieve degenerate phase matching for deflecting said beam into the second order, and (d) using said second order diffracted beam as the output of said acousto-optic deflector.
Claim 7
Dependent Claim
52 words
A method as recited in claim 4 wherein the crystal comprises a TeO 2 crystal and wherein the acoustic waves are propagated in the [110] direction of the said TeO 2 crystal and the said laser beam is directed to be incident close to the optic axis of said TeO 2 crystal.
References Cited (Backward Citations)
US4037933A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-02 | 1982-04-03 | 1982-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-02 | 1986-04-03 | 1986-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-02 | 1990-04-03 | 1990-10-03 | $7700.00 | Window Closed / Lapsed |