US3915572A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Combined dual scatter, local oscillator laser doppler velocimeter
Assignee: National Aeronautics and Space Administration
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Filing: 1974-02-27
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Granted: 1975-10-28
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Expires: 1994-02-27
Abstract
Abstract A laser Doppler velocimeter is described which is capable of effectively measuring two different velocity components of a fluid simultaneously. Such a velocimeter includes a pair of coherent beams of laser light which are focused to an intersection point through which flow particles within the fluid whose velocity is to be measured. Both beams are plane polarized with the plane of polarization of one being rotated normally with respect to the other, with the result that the scattered radiation is separable into two different beams respectively corresponding to the two incident beams. Such scattered radiation is Doppler shifted by the moving particles and is collected for conventionally providing a measurement of the velocity of any particle flowing through the intersection point on a path which is generally transverse thereto. Moreover, the wavelength of the light scattered by the particles from one of the beams is compared to the wavelength of such beam prior to it being Doppler shifted by the moving particles. This comparison provides a measurement of another component of the particle velocity, which measurement can be combined with the first measurement to provide a resultant velocity in a two-dimensional reference frame.
Inventors
- 👤 Kenneth L Orloff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:06
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/02; G01S17/50; G01P; G01P5/00; G01P5/26
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
181 words
A Doppler velocimeter for measuring two velocity components of a particle comprising means for generating a first pair of beams of electromagnetic radiation which are coherent with respect to one another; means for focusing both of said beams at said particle for the scattering therefrom of electromagnetic radiation which has a Doppler shifted frequency and from which a Doppler shifted beam which corresponds to one of said coherent first pair of beams is separable; means for collecting at least a portion of said scattered electromagnetic radiation to provide a measurement indicative of the component of velocity of said particle along a first path normal to the bisector of the angle formed between said first pair of beams at their point of incidence on said particle, and means for comparing the Doppler shifted frequency of the radiation scattered by said particle from said one of said coherent beams with the frequency of said beam prior to said Doppler shift to provide a measurement indicative of the component of velocity of said particle along a second path substantially perpendicular to said first path.
Claim 2
Dependent Claim
181 words
A Doppler velocimeter for measuring two velocity components of a particle comprising means for generating a first pair of beams of electromagnetic radiation which are coherent with respect to one another; means for focusing both of said beams at said particle for the scattering therefrom of electromagnetic radiation which has a Doppler shifted frequency and from which a Doppler shifted beam which corresponds to one of said coherent first pair of beams is separable; means for collecting at least a portion of said scattered electromagnetic radiation to provide a measurement indicative of the component of velocity of said particle along a first path normal to the bisector of the angle formed between said first pair of beams at their point of incidence on said particle, and means for comparing the Doppler shifted frequency of the radiation scattered by said particle from said one of said coherent beams with the frequency of said beam prior to said Doppler shift to provide a measurement indicative of the component of velocity of said particle along a second path substantially perpendicular to said first path.
Claim 3
Dependent Claim
46 words
The Doppler velocimeter of claim 1 wherein said means for generating said first pair of coherent beams of electromagnetic energy includes a laser for generating coherent light for said pair of beams, and means for dividing the output of said laser into said pair of beams.
Claim 4
Dependent Claim
37 words
The Doppler velocimeter of claim 1 wherein means are included for shifting the frequency of one of said first pair of coherent beams relative to the other to directionally bias a portion of the scattered electromagnetic radiation.
Claim 5
Dependent Claim
156 words
The Doppler velocimeter of claim 1 wherein said means for comparing the Doppler shifted wavelength of the radiation scattered by said particle from said one of said beams with the wavelength of said beam prior to said Doppler shift, includes means for separating said one of said pair of coherent beams into a first portion to be focused onto said particle for Doppler shifting of its frequency and a reference portion to be compared with the Doppler shifted wavelength of said first portion to provide said measurement indicative of said component of velocity on said second path; and means for shifting the frequency of said first portion of said beam prior to the Doppler shifting thereof by said particle, relative both to said reference portion thereof and to said other coherent beam to directionally bias both of said measurements of velocity components whereby said measurements also indicate the vector velocity of said particle in two-dimensional flow.
Claim 6
Dependent Claim
111 words
The Doppler velocimeter of claim 1 wherein said means for generating a first pair of coherent beams of electromagnetic radiation generates beaMs which are plane polarized and have differing directions of polarization; and said means for comparing the Doppler shifted frequency of the radiation scattered by said particle from said one of said beams, with the frequency of said beam prior to said Doppler shift includes means for combining a portion of said one coherent beam with a portion of the electromagnetic radiation scattered from said particle which corresponds thereto, to provide a heterodyned resultant representative of the amplitude and direction of the velocity of said particle along said second path.
Claim 7
Dependent Claim
99 words
The Doppler velocimeter of claim 5 wherein said means for collecting at least a portion of said scattered electromagnetic radiation to provide a measurement indicative of the component of velocity of said particle along said first path includes means for separating said scattered electromagnetic radiation into a pair of Doppler shifted beams corresponding individually to said pair of coherent beams, and means for individually collecting said Doppler shifted beams to provide two measurements of the component of said velocity along said first path which are combinable to eliminate undesired components of such measurements common to both of said beams.
Claim 8
Dependent Claim
155 words
The Doppler velocimeter of claim 5 whrein said means for comparing the Doppler shifted frequency of the radiation scattered by said particle from said one of said beams with the frequency of said beam prior to said Doppler shift, includes means for separating said one of said pair of coherent beams into a first portion to be focused onto said particle for Doppler shifting of its frequency and a reference portion to be compared with the Doppler shifted frequency of said first portion to provide said measurement indicative of said component of celocity on said second path; and means for shifting the frequency of said first portion of said beam prior to the Doppler shifting thereof by said particle, relative both to said reference portion thereof and to said other coherent beam to directionally bias both of said measurements of velocity components whereby said measurements also indicate the direction of said velocities along said paths.
Claim 9
Dependent Claim
37 words
The Doppler velocimeter of claim 5 wherein said means for generating a first pair of coherent beams of electromagnetic radiation generates plane polarized beams which have directions of polarization which are orthogonal with respect to one another.
Claim 10
Dependent Claim
101 words
A Doppler velocimeter of claim 8 wherein said means for generating said first pair of coherent beams of electromagnetic energy includes a laser for generating coherent light for said pair of beams, and means for dividing the output of said laser into said pair of coherent beams and separating one of said pair of beams into a first portion to be focused onto said particle for Doppler shifting of its frequency and a reference portion to be compared with the Doppler shifted frequency of said first portion to provide said measurement indicative of said component of velocity along said second path.
Claim 11
Dependent Claim
99 words
A Doppler velocimeter of claim 9 wherein said means for collecting at least a portion of said scattered electromagnetic radiation to provide a measurement indicative of the component of velocity of said particle along said first path includes means for separating said scattered electromagnetic radiation into a pair of Doppler shifted beams corresponding individually to said pair of coherent beams, and means for individually collecting said Doppler shifted beams to provide two measurements of the component of said velocity along said first path which are combinable to eliminate undesired components of such measurements common to both of said beams.
Claim 12
Dependent Claim
180 words
A velocimeter for developing signals representative of the velocity of a particle along first and second paths comprising: means for generating first and second beams of coherent electromagnetic radiation; means for converting said second beam of radiation to a directionally biased beam of radiation; means for focusing said first beam of radiation and said biased beam of radiation upon said particle with radiation scattering from said particle and interference fringes produced at the intersection of said beams; means for detecting a portion of said scattered radiation and generating a signal representative of the amplitude and direction of the velocity of said particle along a first path through said fringes and perpendicular to the bisector of the angle formed by the convergence of said first beam and said biased beam; means for combining a portion of said first beam of radiation and a portion of said scattered radiation; means for detecting said combined radiation and generating a beat signal representative of the amplitude and direction of the velocity of said particle along a second path substantially orthogonal to said first path.
Claim 13
Dependent Claim
180 words
A velocimeter for developing signals representative of the velocity of a particle along first and second paths comprising: means for generating first and second beams of coherent electromagnetic radiation; means for converting said second beam of radiation to a directionally biased beam of radiation; means for focusing said first beam of radiation and said biased beam of radiation upon said particle with radiation scattering from said particle and interference fringes produced at the intersection of said beams; means for detecting a portion of said scattered radiation and generating a signal representative of the amplitude and direction of the velocity of said particle along a first path through said fringes and perpendicular to the bisector of the angle formed by the convergence of said first beam and said biased beam; means for combining a portion of said first beam of radiation and a portion of said scattered radiation; means for detecting said combined radiation and generating a beat signal representative of the amplitude and direction of the velocity of said particle along a second path substantially orthogonal to said first path.
Claim 14
Dependent Claim
24 words
A velocimeter as set forth in claim 11 wherein said biased beam of radiation has a different frequency than said first beam of radiation.
Claim 15
Dependent Claim
32 words
A velocimeter as set forth in claim 11 wherein said converting means comprises a Bragg cell and said biased beam of radiation has a different frequency than said first beam of radiation.
Claim 16
Dependent Claim
36 words
A velocimeter as claimed in claim 12 wherein said first and second beams are plane polarized and the plane of polarization of said first beam is orthogonal to the plane of polarization of said second beam.
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) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |