US3709599A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser doppler flow probe with high spatial resolution
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1970-11-10
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Granted: 1973-01-09
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Expires: 1990-11-10
Abstract
Abstract An arrangement for microscopic measurement of velocities in a flow field comprises a laser beam of a predetermined frequency which is focussed on a selected volume of the fluid flowing in a field to produce an unscattered as well as a scattered component beam. The two component beams are directed onto a photodetector which mixes them and produces a corresponding electrical heterodyne signal which, after amplification and passage through a band-pass filter, is applied to an amplitude discriminator to delete all signals below a preselected amplitude level and thereby correspondingly improve the spatial resolution of the volume of fluid desired to be measured. The output of the discriminator is then applied to a frequency measuring instrument.
Inventors
- 👤 P Iten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:12
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/02; G01S17/50; G01F; G01F1/00; G01F1/66; G01F1/661; H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; H01S3/081; H01S3/083
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
114 words
A method of microscopic measurement of velocities in a flow field which comprises the steps of focusing a laser beam of a predetermined frequency on a selected volume of a fluid medium flowing in a field and which thereby produces an unscattered component beam as well as a scattered component beam, collecting both of said component beams and mixing their frequencies to produce a corresponding electrical heterodyne signal, subjecting said electrical signal to a discriminating function to eliminate all signal components below a preselected amplitude level to thereby correspondingly improve the spatial resolution of the volume of fluid desired to be measured and measuring the frequency of the signals above said preselected amplitude level.
Claim 2
Independent Claim
114 words
A method of microscopic measurement of velocities in a flow field which comprises the steps of focusing a laser beam of a predetermined frequency on a selected volume of a fluid medium flowing in a field and which thereby produces an unscattered component beam as well as a scattered component beam, collecting both of said component beams and mixing their frequencies to produce a corresponding electrical heterodyne signal, subjecting said electrical signal to a discriminating function to eliminate all signal components below a preselected amplitude level to thereby correspondingly improve the spatial resolution of the volume of fluid desired to be measured and measuring the frequency of the signals above said preselected amplitude level.
Claim 3
Dependent Claim
132 words
Apparatus for microscopic measurement of velocities in a flow field which comprises means producing a laser beam of a predetermined frequency, means focusing said laser beam on a selected volume of fluid flowing in a field which thereby produces an unscattered component beam as well as a scattered component beam, a photodetector, means directing said unscattered and scattered component beams onto said photodetector in which their respective frequencies are mixed to produce at the output thereof a corresponding electrical heterodyne signal, circuit means connecting the output from said photodetector to an amplitude discriminator to delete all signals below a preselected amplitude level to thereby correspondingly improve the spatial resolution of the volume of fluid desired to be measured, and circuit means applying the output from said discriminator to a frequency measuring instrument.
Claim 4
Dependent Claim
132 words
Apparatus for microscopic measurement of velocities in a flow field which comprises means producing a laser beam of a predetermined frequency, means focusing said laser beam on a selected volume of fluid flowing in a field which thereby produces an unscattered component beam as well as a scattered component beam, a photodetector, means directing said unscattered and scattered component beams onto said photodetector in which their respective frequencies are mixed to produce at the output thereof a corresponding electrical heterodyne signal, circuit means connecting the output from said photodetector to an amplitude discriminator to delete all signals below a preselected amplitude level to thereby correspondingly improve the spatial resolution of the volume of fluid desired to be measured, and circuit means applying the output from said discriminator to a frequency measuring instrument.
Claim 5
Dependent Claim
29 words
Apparatus as defined in claim 2 and which further includes a band-pass filter inserted in the circuit means extending from the output of said photodetector to said amplitude discriminator.
References Cited (Backward Citations)
US3516751A
Cited
US3510662A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |