US3584956A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser anemometer frequency to voltage converters
Assignee: Laser Systems and Electronics Inc
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Filing: 1968-10-23
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Granted: 1971-06-15
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Expires: 1988-10-23
Abstract
Abstract A frequency to voltage converter for use with a laser velocity measuring system whereby a laser beam is passed through a flowing media, and a portion of the Doppler shifted beam is optically combined with the nonshifted beam to produce a fixed homodyne signal which is then applied to a photodetector to produce a modulated electrical signal. This modulated electrical signal is then passed through a high pass filter and a wide band amplifier having automatic gain control to each of two isolation amplifiers, one of which applies its signal to a summing amplifier directly, while the other amplifier applies its signal through a variable delay line to the summing amplifier to ensure that a continuous output signal will be produced. The output of the summing amplifier is then applied to a mixer along with the output of a local oscillator so that another modulated signal having a frequency greater than the frequency of the combined optical signal is produced which is then passed through a high pass filter to a discriminator. The output of the discriminator is then filtered through a low-pass filter and applied to an offset and gain control circuit to produce an output voltage which varies directly with the velocity of the flowing media.
Inventors
- 👤 Robin H Hines
- 👤 John I Shipp
- 👤 Richard G Ray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:03
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/66; G01F1/661; G01P; G01P5/00; G01P5/26
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
164 words
A velocity measuring system comprising: means for producing a beam of monochromatic light, means for directing at least a portion of said beam onto a flowing media so that at least a portion of the directed beam is shifted in frequency by an amount proportional to the velocity of said flowing media, means for combining at least a part of said shifted portion of said beam with an unshifted beam of monochromatic light to produce a combined beam, means for converting said combined beam into an electrical signal, varying in amplitude in the same manner as said combined beam varied in intensity, means for mixing said electrical signal with a sinusoidal signal so that a mixed frequency modulated signal having a frequency greater than the frequency of said combined beam is produced, and discriminator means for converting said modulated signal to a direct current voltage signal so that the amplitude of said direct current voltage varies directly with the velocity of said flowing media.
Claim 2
Dependent Claim
164 words
A velocity measuring system comprising: means for producing a beam of monochromatic light, means for directing at least a portion of said beam onto a flowing media so that at least a portion of the directed beam is shifted in frequency by an amount proportional to the velocity of said flowing media, means for combining at least a part of said shifted portion of said beam with an unshifted beam of monochromatic light to produce a combined beam, means for converting said combined beam into an electrical signal, varying in amplitude in the same manner as said combined beam varied in intensity, means for mixing said electrical signal with a sinusoidal signal so that a mixed frequency modulated signal having a frequency greater than the frequency of said combined beam is produced, and discriminator means for converting said modulated signal to a direct current voltage signal so that the amplitude of said direct current voltage varies directly with the velocity of said flowing media.
Claim 3
Dependent Claim
44 words
A system as in claim 1 including means for delaying in time a portion of said electrical signal and for combining the delayed and undelayed portions, of said electrical signal, so that the direct current voltage produced by said discriminator means is substantially continuous.
Claim 4
Dependent Claim
75 words
A system as in claim 2 wherein said delaying and combining means includes a first isolation amplifier for receiving and amplifying said electrical signal, a second isolation amplifier for receiving and amplifying said electrical signal, a delay line connected to the output of said second isolation amplifier and a summing amplifier having as its inputs the outputs of said first isolation amplifier and said delay line and having its output connected to said mixing means.
Claim 5
Dependent Claim
22 words
A system as in claim 1 wherein said unshifted beam is the portion of said directed beam which is unshifted in frequency.
Claim 6
Dependent Claim
14 words
A system as in claim 4 wherein said directed beam passes through said media.
Claim 7
Dependent Claim
61 words
A system as in claim 5 wherein said directing means includes a first lens for focusing said directed beam onto said media, a second lens for focusing the portion of the shifted beam scattered at a given angle, a third lens for focusing said unshifted beam and mirror means for combining the beam scattered at a given angle and unshifted beam.
Claim 8
Dependent Claim
17 words
A system as in claim 6 wherein said means for converting said combined beam includes a photodetector.
Claim 9
Dependent Claim
21 words
A System as in claim 1 including means for amplifying said electrical signal before said signal is conveyed to said mixer.
Claim 10
Dependent Claim
15 words
A system as in claim 8 including local oscillator means for producing said sinusoidal signal.
Claim 11
Dependent Claim
14 words
A system as in claim 1 wherein said producing means is a helium-neon laser.
Claim 12
Dependent Claim
19 words
A system as in claim 1 wherein said mixed signal is a suppressed carrier, upper and lower sideband signal.
Claim 13
Dependent Claim
30 words
A system as in claim 1 including means for removing one of said sidebands and wherein said discriminator means converts the remaining sideband signal to a direct current voltage signal.
Claim 14
Dependent Claim
14 words
A system as in claim 12 wherein said removing means removes the lower sideband.
Claim 15
Dependent Claim
146 words
A velocity measuring system comprising: means for producing a beam of monochromatic light, means for directing a portion of said monochromatic beam onto a flowing media whose velocity is being measured so that a portion of the directed beam is shifted in frequency by an amount proportional to the velocity of said flowing media, means for combining at least a portion of said shifted beam with an unshifted beam of monochromatic light to produce a combined beam, means for converting said combined beam into an electrical signal, means for delaying in time a portion of said electrical signal and for combining the delayed and undelayed portions of said electrical signal so that said electrical signal is continuous and substantially undistorted, and means for converting said electrical signal into a direct current voltage signal having an amplitude which varies directly with the velocity of said flowing media.
Claim 16
Dependent Claim
146 words
A velocity measuring system comprising: means for producing a beam of monochromatic light, means for directing a portion of said monochromatic beam onto a flowing media whose velocity is being measured so that a portion of the directed beam is shifted in frequency by an amount proportional to the velocity of said flowing media, means for combining at least a portion of said shifted beam with an unshifted beam of monochromatic light to produce a combined beam, means for converting said combined beam into an electrical signal, means for delaying in time a portion of said electrical signal and for combining the delayed and undelayed portions of said electrical signal so that said electrical signal is continuous and substantially undistorted, and means for converting said electrical signal into a direct current voltage signal having an amplitude which varies directly with the velocity of said flowing media.
Claim 17
Dependent Claim
147 words
In a velocity measuring system for determining the velocity of a flowing media with means for directing a portion of a laser beam onto the media so that a portion of the directed portion is scattered and shifted in frequency an amount proportional to the velocity of the media, means for combining at least a portion of the shifted beam with an unshifted beam and converting this optical signal into an electrical signal, and means for converting the electrical signal into a direct current voltage signal having an amplitude proportional to the velocity of said media, the improvement in said converting means comprising: means for mixing said electrical signal with a sinusoidal signal to produce a mixed frequency modulated signal, and discriminator means for converting said mixed signal to a direct current voltage signal having an amplitude which varies directly with the velocity of said flowing media.
Claim 18
Dependent Claim
147 words
In a velocity measuring system for determining the velocity of a flowing media with means for directing a portion of a laser beam onto the media so that a portion of the directed portion is scattered and shifted in frequency an amount proportional to the velocity of the media, means for combining at least a portion of the shifted beam with an unshifted beam and converting this optical signal into an electrical signal, and means for converting the electrical signal into a direct current voltage signal having an amplitude proportional to the velocity of said media, the improvement in said converting means comprising: means for mixing said electrical signal with a sinusoidal signal to produce a mixed frequency modulated signal, and discriminator means for converting said mixed signal to a direct current voltage signal having an amplitude which varies directly with the velocity of said flowing media.
Claim 19
Dependent Claim
43 words
In a system as in claim 15, the further improvement including mean for delaying in time a portion of said electrical signal and for combining the delayed and undelayed portions of said signal so that said electrical signal is continuous and substantially undistorted.
Claim 20
Independent Claim
123 words
A method of measuring the velocity of a flowing media comprising the steps of: directing a beam of monochromatic light onto said media so that a portion of said beam is shifted in frequency an amount proportional to the velocity of said media, combining the shifted beam with an unshifted beam to produce a combined beam, converting said combined beam into an electrical signal varying in amplitude in the same manner as said combined beam varied in intensity, mixing said electrical signal with a sinusoidal signal so that a frequency modulated mixed signal is produced, and converting the mixed signal to a direct current voltage signal so that the amplitude of said voltage signal varies directly with the velocity of said flowing media.
Claim 21
Independent Claim
123 words
A method of measuring the velocity of a flowing media comprising the steps of: directing a beam of monochromatic light onto said media so that a portion of said beam is shifted in frequency an amount proportional to the velocity of said media, combining the shifted beam with an unshifted beam to produce a combined beam, converting said combined beam into an electrical signal varying in amplitude in the same manner as said combined beam varied in intensity, mixing said electrical signal with a sinusoidal signal so that a frequency modulated mixed signal is produced, and converting the mixed signal to a direct current voltage signal so that the amplitude of said voltage signal varies directly with the velocity of said flowing media.
Claim 22
Dependent Claim
42 words
A method as in claim 17 including the additional steps of delaying in time a portion of said electrical signal and adding together the delayed and undelayed portions of said electrical signal so that the electrical signal is continuous and substantially undistorted.
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) | 1974-06-14 | 1974-12-14 | 1975-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-14 | 1978-12-14 | 1979-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-14 | 1982-12-14 | 1983-06-15 | $7700.00 | Window Closed / Lapsed |