Patent US2907921A successfully refreshed from Google Patents.
Patent US3735279A successfully refreshed from Google Patents.
US3735279A
Expired / Lapsed
US
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Colinear heterodyne frequency modulator
Assignee: Raytheon Co
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Filing: 1970-12-10
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Granted: 1973-05-22
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Expires: 1990-12-10
Abstract
Abstract An apparatus to produce Brillouin scattering by means of two oppositely directed colinear optical beams, frequency-translated and of varying power level, in a time sequence suitable for processing doppler-shifted radar target echoes by means of a simplified optical heterodyne detection system.
Inventors
- 👤 M Pedinoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:40
CPC Classifications
G; G02; G02F; G02F2/00; G02F2/002; H; H01; H01S; H01S3/00; H01S3/10; H01S3/106; H01S3/108; H01S3/1086; H01S3/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
255 words
In a frequency modulating apparatus, the combination of: an active laser medium, means coupled to said medium for inducing a population inversion therein, and means including optical elements positioned about said medium for stimulating coherent emission from said active medium for providing a first pair of oppositely propagating coherent electromagnetic continuous optical waves travelling along a selected path which extends through said medium; a frequency modulator positioned in the path of the first pair of optical waves and including radio frequency pulsed wave energy beam means for providing an acoustic wave in said frequency modulator for receiving the first pair of optical waves and acoustic wave, and means for diffracting the first pair of optical waves to produce a second pair of oppositely directed optical waves of opposite frequency translation and for transmitting the frequency translated optical waves along oppositEly directed colinear paths angled with respect to the path of the first pair of optical waves; means positioned in a first of the oppositely directed colinear paths for redirecting a first of the pair of the frequency translated optical waves through said frequency modulator, the pulse repition period of the radio frequency pulses and the strength of the acoustic wave being such to enable the redirected wave to pass through said frequency modulator essentially unaltered; and a photodetector receiver positioned in a second of the oppositely directed colinear paths for receiving the redirected first of the pair of the frequency translated optical waves and a second of the pair of the frequency translated optical waves.
Claim 2
Dependent Claim
255 words
In a frequency modulating apparatus, the combination of: an active laser medium, means coupled to said medium for inducing a population inversion therein, and means including optical elements positioned about said medium for stimulating coherent emission from said active medium for providing a first pair of oppositely propagating coherent electromagnetic continuous optical waves travelling along a selected path which extends through said medium; a frequency modulator positioned in the path of the first pair of optical waves and including radio frequency pulsed wave energy beam means for providing an acoustic wave in said frequency modulator for receiving the first pair of optical waves and acoustic wave, and means for diffracting the first pair of optical waves to produce a second pair of oppositely directed optical waves of opposite frequency translation and for transmitting the frequency translated optical waves along oppositEly directed colinear paths angled with respect to the path of the first pair of optical waves; means positioned in a first of the oppositely directed colinear paths for redirecting a first of the pair of the frequency translated optical waves through said frequency modulator, the pulse repition period of the radio frequency pulses and the strength of the acoustic wave being such to enable the redirected wave to pass through said frequency modulator essentially unaltered; and a photodetector receiver positioned in a second of the oppositely directed colinear paths for receiving the redirected first of the pair of the frequency translated optical waves and a second of the pair of the frequency translated optical waves.
Claim 3
Dependent Claim
38 words
An apparatus as in claim 1 wherein the material of said modulator is selected from the group consisting of germanium, gallium arsenide and tellurium, and wherein said means for producing the acoustic wave comprises a piezoelectric ultrasonic transducer.
Claim 4
Dependent Claim
23 words
An apparatus as in claim 1 wherein said frequency modulator includes means capable of operating said frequency modulator close to a Bragg angle.
Claim 5
Dependent Claim
18 words
An apparatus as in claim 1 wherein said photodetector receiver includes means for producing a heterodyne output signal.
Claim 6
Independent Claim
266 words
A method for generating two oppositely directed, continuous wave and pulse modulated colinear and parallel electromagnetic wave energy beams, one of the beams having a frequency translation opposite from the frequency translation of the other of the beams, comprising the steps of: directing a pair of oppositely propagating electromagnetic continuous wave energy beams and a radio frequency pulsed wave energy beam into a frequency modulating apparatus, the continuous wave energy beams being directed substantially at the Bragg angle or at a multiple thereof with respect to the frequency modulator; frequency modulating the continuous wave energy beams by the pulsed wave energy beam in the frequency modulating apparatus to simultaneously produce an interaction of continuous wave modulation energy of the two continuous wave beams with pulse modulation energy to produce from the interaction the two oppositely directed, continuous wave and pulse modulated colinear and parallel electro-magnetic wave energy beams having opposite frequency translations; producing a time delay in a first of the two frequency translated beams less than the pulse repetition period of the modulating pulse obtained in said frequency modulating step by propagation of the first beam over an optical path having a length sufficient to produce the time delay; redirecting the time delayed beam through the frequency modulating apparatus; maintaining the intensity of the pulse wave energy beam in the frequency modulating apparatus at a level not sufficiently intense to produce modulation of the redirected beam; and recombining and photo-mixing the time delayed first beam and the second of the two frequency translated beams for detecting the time position of the time delayed optical signal.
Claim 7
Independent Claim
266 words
A method for generating two oppositely directed, continuous wave and pulse modulated colinear and parallel electromagnetic wave energy beams, one of the beams having a frequency translation opposite from the frequency translation of the other of the beams, comprising the steps of: directing a pair of oppositely propagating electromagnetic continuous wave energy beams and a radio frequency pulsed wave energy beam into a frequency modulating apparatus, the continuous wave energy beams being directed substantially at the Bragg angle or at a multiple thereof with respect to the frequency modulator; frequency modulating the continuous wave energy beams by the pulsed wave energy beam in the frequency modulating apparatus to simultaneously produce an interaction of continuous wave modulation energy of the two continuous wave beams with pulse modulation energy to produce from the interaction the two oppositely directed, continuous wave and pulse modulated colinear and parallel electro-magnetic wave energy beams having opposite frequency translations; producing a time delay in a first of the two frequency translated beams less than the pulse repetition period of the modulating pulse obtained in said frequency modulating step by propagation of the first beam over an optical path having a length sufficient to produce the time delay; redirecting the time delayed beam through the frequency modulating apparatus; maintaining the intensity of the pulse wave energy beam in the frequency modulating apparatus at a level not sufficiently intense to produce modulation of the redirected beam; and recombining and photo-mixing the time delayed first beam and the second of the two frequency translated beams for detecting the time position of the time delayed optical signal.
Claim 8
Dependent Claim
218 words
In a frequency modulating apparatus, the combination of: a first active laser medium; a first resonant optical cavity having an axis and being positioned about said active laser medium, said cavity having first and second reflectors for stimulating coherent emission from said active laser medium for providing a low power coherent electromagnetic light wave propagating along said axis; a second laser medium; a second optical resonant cavity being positioned about said second laser medium and having an axis colinear with said first cavity axis, said second optical resonant cavity comprising said second reflector and a third rotatable reflector for enabling Q-switching of said second laser medium; a frequency modulator including means for providing an acoustic wave in said frequency modulator; said second reflector being constructed and positioned to transmit the low-power optical wave emitted to said freqUency modulator, thereby yielding a low-power diffracted optical beam, and said rotatable reflector posi-tioned in the path of said optical wave for amplification and refection thereof by said rotatable reflector in one position of alignment during rotation thereof for Q-switched retransmission of the optical wave into said frequency modulator to produce therefrom a high powered diffracted optical pulse oppositely directed from the low-power diffracted optical beam; and a photodetector receiver in the path of the low-power diffracted optical beam for reception thereof.
Claim 9
Dependent Claim
218 words
In a frequency modulating apparatus, the combination of: a first active laser medium; a first resonant optical cavity having an axis and being positioned about said active laser medium, said cavity having first and second reflectors for stimulating coherent emission from said active laser medium for providing a low power coherent electromagnetic light wave propagating along said axis; a second laser medium; a second optical resonant cavity being positioned about said second laser medium and having an axis colinear with said first cavity axis, said second optical resonant cavity comprising said second reflector and a third rotatable reflector for enabling Q-switching of said second laser medium; a frequency modulator including means for providing an acoustic wave in said frequency modulator; said second reflector being constructed and positioned to transmit the low-power optical wave emitted to said freqUency modulator, thereby yielding a low-power diffracted optical beam, and said rotatable reflector posi-tioned in the path of said optical wave for amplification and refection thereof by said rotatable reflector in one position of alignment during rotation thereof for Q-switched retransmission of the optical wave into said frequency modulator to produce therefrom a high powered diffracted optical pulse oppositely directed from the low-power diffracted optical beam; and a photodetector receiver in the path of the low-power diffracted optical beam for reception thereof.
References Cited (Backward Citations)
US3297876A
Cited
US3544805A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |