US3825341A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Doppler radar using laser
Assignee: Toshiba Corp
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Filing: 1971-06-11
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Granted: 1974-07-23
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Expires: 1991-06-11
Abstract
Abstract A Doppler radar comprising a mode-locked laser oscillating in a single longitudinal mode which generates a laser beam including a plurality of electromagnetic waves of an equal frequency interval; a light transmitting telescope for directing said laser beam to a moving object; a light receiving telescope for receiving from the moving object a plurality of reflected waves subjected to Doppler shift; a photofilter for eliminating background noises from output beam of the light receiving telescope; a photodiode for mixing said plurality of waves and drawing out from the waves only the signal which has a frequency corresponding to the aforementioned equal frequency interval; a photomultiplier for mixing a plurality of reflected waves after their passage through the photofilter and drawing out from the reflected waves only the signal which has a frequency interval corresponding to the equal frequency interval of the transmitted waves; a circuit for mixing outputs from the photodiode and photomultiplier and a frequency counter for counting the frequency of the output signal from the mixing circuit to detect the relative speed of the moving object to that of the observing body.
Inventors
- 👤 K Goto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:41
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/02; G01S17/50; G01P; G01P3/00; G01P3/36; G01P3/366; G01S17/58
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
182 words
A Doppler radar comprising a means for generating a plurality of coherent electromagnetic waves having a single longitudinal mode and an equal frequency interval, means connected to said generating means for directing said electromagnetic waves to a moving object, means for receiving from the moving object a plurality of reflected waves subjected to the Doppler shift, a first means for forming signals having a frequency corresponding to the aforementioned equal frequency interval, a second means connected to said receiving means for mixing a plurality oF reflected waves and drawing out from the reflected waves only the signal which has a frequency corresponding to the equal frequency interval of the transmitted laser beams and subjected to Doppler shift, using beat signals between reflective waves, a third means connected to the output terminals of said first and second means for mixing outputs therefrom and obtaining beat signals between the signals formed by the first means and those drawm out by the second means, and means for detecting the speed of the moving object relative to an observing apparatus on which the radar is disposed.
Claim 2
Dependent Claim
182 words
A Doppler radar comprising a means for generating a plurality of coherent electromagnetic waves having a single longitudinal mode and an equal frequency interval, means connected to said generating means for directing said electromagnetic waves to a moving object, means for receiving from the moving object a plurality of reflected waves subjected to the Doppler shift, a first means for forming signals having a frequency corresponding to the aforementioned equal frequency interval, a second means connected to said receiving means for mixing a plurality oF reflected waves and drawing out from the reflected waves only the signal which has a frequency corresponding to the equal frequency interval of the transmitted laser beams and subjected to Doppler shift, using beat signals between reflective waves, a third means connected to the output terminals of said first and second means for mixing outputs therefrom and obtaining beat signals between the signals formed by the first means and those drawm out by the second means, and means for detecting the speed of the moving object relative to an observing apparatus on which the radar is disposed.
Claim 3
Dependent Claim
33 words
A Doppler radar according to claim 1, wherein said coherent electromagnetic waves are mode locked and the first means comprises means for mixing a plurality of electromagnetic waves generated by the generating means.
Claim 4
Dependent Claim
68 words
A Doppler radar according to claim 2, wherein the generating means is a ruby laser and the reflected wavereceiving means includes a photofilter for eliminating background noises, the first mixing means includes a photodiode, the second mixing means includes a photomultiplier, the relative speed detector includes a travelling wave tube for amplifying output from the third mixing means and a frequency counter connected to the travelling wave tube.
Claim 5
Dependent Claim
22 words
A Doppler radar according to claim 3, wherein the transmitting and receiving means, respectively, include a light-transmitting telescope and a light-receiving telescope.
Claim 6
Dependent Claim
60 words
A Doppler radar according to claim 1, wherein there is connected between the first and third mixing means a device for delaying output from the first mixing means by a length of time required for the originally transmitted electromagnetic waves to be received in the form of reflected waves from the moving object and conducted to the third mixing means.
Claim 7
Dependent Claim
65 words
A Doppler radar according to claim 3, wherein the laser is a pulsed laser for generating pulses and there is disposed between the output terminal of the photodiode and the input terminal of the third mixing means, a repetition frequency generator which, when it is supplied from the photodiode with a signal having a frequency corresponding to the equal frequency interval, repeatedly generates output signals.
Claim 8
Dependent Claim
46 words
A Doppler radar according to claim 2, wherein the generating means is a He-Ne gas laser and includes a frequency stabilizer and resonator length-controlling means connected to the output terminal of the first mixing means to control the length of a resonator included in said laser.
Claim 9
Dependent Claim
46 words
A Doppler radar according to claim 2, wherein the generating means is a carbon dioxide gas laser including resonator length-controlling means, and the first and second mixing means include Ge-Cu diodes, with the output terminal of the first mixing means connected to the resonator length-controlling means.
Claim 10
Dependent Claim
61 words
A Doppler radar according to claim 1, wherein said coherent electromagnetic waves are mode locked, the generating means is a laser provided with a resonator length-controlling means for fixing the length of a resonator included therein, and the first means includes generating means for generating a signal having a frequency corresponding to the equal frequency interval between the generated electromagnetic waves.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |