US3897152A
Expired / Lapsed
US
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Laser doppler velocimeter
Assignee: United States Department of the Air Force
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Filing: 1974-02-04
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Granted: 1975-07-29
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Expires: 1994-02-04
Abstract
Abstract A beam from a laser penetrates a two-dimensional Bragg cell and is diffracted into four output beams each with different frequencies and focused to a point in moving media where two components of velocity are to be obtained. Polarization rotation plates can be used to intercept the four output beams from the two-dimensional Bragg cell in order to adjust the orientation of polarization which eliminates cross-talk. The scattered light from the probe point in the moving medium is optically collected and projected into a photomultiplier tube, the output thereof being fed to carrier frequency separation and doppler data processing electronics. The two-dimensional Bragg cell consists of a pair of right angle intersecting water columns with a pair of oscillating ultrasonic cyrstals located near the intersecting point and perpendicular to one each of the water columns. Light penetration from a laser beam is obtained by placing a pair of windows of optical quality on both sides of the cell''s housing at the intersecting point of the water columns.
Inventors
- 👤 William M Farmer
- 👤 James O Hornkohl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:01
CPC Classifications
G; G01; G01P; G01P13/00; G01P13/02; G01P5/00; G01P5/26; G01S; G01S17/00; G01S17/02; G01S17/50
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
222 words
A laser doppler velocimeter system comprising: a. a laser beam source; b. means for generating four output light beams from the laser beam with each light beam having a different frequency, the generating means including: 1. a housing containing first and second intersecting columns of water, 2. a pair of transparent members on opposite surfaces of the housing at the intersecting points of the water columns for passage of light from the laser beam source, 3. a pair of Bragg crystals positioned one each in the first and second intersecting columns of water, and 4. a pair of oscillators having different frequencies activating one each of the pair of Bragg crystals; c. a collimating lens intersecting the four output beams to focus upon a test point; d. four polarization rotation plates interposed between the beam generating means and the collimating lens with one each of the rotating plates positioned to intercept one each of the output light beams for eliminating predetermined velocity components; and e. means for collecting scattered light from the test point including 1. a lens system intercepting the scattered light from the test point, 2. a photomultiplier tube positioned to receive the light from the lens system, 3. a carrier frequency separator fed by the photomultiplier tube, and 4. a doppler data processor fed by the carrier frequency separator.
Claim 2
Dependent Claim
222 words
A laser doppler velocimeter system comprising: a. a laser beam source; b. means for generating four output light beams from the laser beam with each light beam having a different frequency, the generating means including: 1. a housing containing first and second intersecting columns of water, 2. a pair of transparent members on opposite surfaces of the housing at the intersecting points of the water columns for passage of light from the laser beam source, 3. a pair of Bragg crystals positioned one each in the first and second intersecting columns of water, and 4. a pair of oscillators having different frequencies activating one each of the pair of Bragg crystals; c. a collimating lens intersecting the four output beams to focus upon a test point; d. four polarization rotation plates interposed between the beam generating means and the collimating lens with one each of the rotating plates positioned to intercept one each of the output light beams for eliminating predetermined velocity components; and e. means for collecting scattered light from the test point including 1. a lens system intercepting the scattered light from the test point, 2. a photomultiplier tube positioned to receive the light from the lens system, 3. a carrier frequency separator fed by the photomultiplier tube, and 4. a doppler data processor fed by the carrier frequency separator.
Claim 3
Dependent Claim
28 words
a pair of transparent members on opposite surfaces of the housing at the intersecting points of the water columns for passage of light from the laser beam source,
Claim 4
Dependent Claim
28 words
a pair of transparent members on opposite surfaces of the housing at the intersecting points of the water columns for passage of light from the laser beam source,
Claim 5
Dependent Claim
12 words
a photomultiplier tube positioned to receive the light from the lens system,
Claim 6
Dependent Claim
12 words
a photomultiplier tube positioned to receive the light from the lens system,
Claim 7
Dependent Claim
10 words
a carrier frequency separator fed by the photomultiplier tube, and
Claim 8
Dependent Claim
10 words
a carrier frequency separator fed by the photomultiplier tube, and
Claim 9
Dependent Claim
18 words
a pair of Bragg crystals positioned one each in the first and second intersecting columns of water, and
Claim 10
Dependent Claim
18 words
a pair of Bragg crystals positioned one each in the first and second intersecting columns of water, and
Claim 11
Dependent Claim
10 words
a doppler data processor fed by the carrier frequency separator.
Claim 12
Dependent Claim
10 words
a doppler data processor fed by the carrier frequency separator.
Claim 13
Dependent Claim
80 words
a pair of oscillators having different frequencies activating one each of the pair of Bragg crystals; c. a collimating lens intersecting the four output beams to focus upon a test point; d. four polarization rotation plates interposed between the beam generating means and the collimating lens with one each of the rotating plates positioned to intercept one each of the output light beams for eliminating predetermined velocity components; and e. means for collecting scattered light from the test point including
Claim 14
Dependent Claim
80 words
a pair of oscillators having different frequencies activating one each of the pair of Bragg crystals; c. a collimating lens intersecting the four output beams to focus upon a test point; d. four polarization rotation plates interposed between the beam generating means and the collimating lens with one each of the rotating plates positioned to intercept one each of the output light beams for eliminating predetermined velocity components; and e. means for collecting scattered light from the test point including
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) | 1978-07-28 | 1979-01-27 | 1979-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-28 | 1983-01-27 | 1983-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-28 | 1987-01-27 | 1987-07-29 | $7700.00 | Window Closed / Lapsed |