US3864041A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Doppler-shift velocity measurement system using a two-frequency laser
Assignee: United States Atomic Energy Commission
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Filing: 1973-06-06
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Granted: 1975-02-04
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Expires: 1993-06-06
Abstract
Abstract A system for determining the velocity of a moving object, including a laser that emits light at two original frequencies to impinge on a reflector included on the object; a beam splitter and a mirror for directing the light emitted from the laser and the light reflected from the object to a photodiode; and a device for displaying an electrical signal generated in the diode that is the difference between one original frequency and the dopplershifted frequency of the other original frequency, the difference in frequency being a function of the velocity of the object and being in a range of values that are conveniently measured.
Inventors
- 👤 James R Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 05:38
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/36; G01P3/366; G01S; G01S17/00; G01S17/02; G01S17/50; G01S17/58
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
243 words
A system for determining the velocity of a moving object, including: a rEflector included on said object; a two-frequency laser for developing frequency gain peaks for emission of light at first and second original frequencies f1 and f2 to impinge on said reflector and be reflected therefrom; a square law light detector, said detector being a photodiode; means for directing light emitted from said laser and light reflected from the object to said detector, the frequencies of said light at frequencies f1 and f2 being reflected from said object and Doppler-shifted to a third frequency f1'' and a fourth frequency f2'', respectively, according to the velocity of said object; means connected to said detector for indicating a difference frequency (f1'' - f2), said means connected to said detector including an oscilloscope for displaying as a trace the difference frequency (f1'' - f2), and a camera for permanently recording the oscilloscope trace; and means for determining the difference between said second frequency f2 and said first frequency f1, the difference frequency (f1'' - f2) added to the difference between the frequencies f2 and f1 being a measure of the velocity of the object, said laser being selected to produce frequencies f1 and f2 relative to the estimated velocity of said object so that all difference frequencies between the frequencies f1, f2, f1'' and f2'', other than the difference frequency (f1'' - f2) are outside the range of response of said detector and said oscilloscope.
Claim 2
Independent Claim
243 words
A system for determining the velocity of a moving object, including: a rEflector included on said object; a two-frequency laser for developing frequency gain peaks for emission of light at first and second original frequencies f1 and f2 to impinge on said reflector and be reflected therefrom; a square law light detector, said detector being a photodiode; means for directing light emitted from said laser and light reflected from the object to said detector, the frequencies of said light at frequencies f1 and f2 being reflected from said object and Doppler-shifted to a third frequency f1'' and a fourth frequency f2'', respectively, according to the velocity of said object; means connected to said detector for indicating a difference frequency (f1'' - f2), said means connected to said detector including an oscilloscope for displaying as a trace the difference frequency (f1'' - f2), and a camera for permanently recording the oscilloscope trace; and means for determining the difference between said second frequency f2 and said first frequency f1, the difference frequency (f1'' - f2) added to the difference between the frequencies f2 and f1 being a measure of the velocity of the object, said laser being selected to produce frequencies f1 and f2 relative to the estimated velocity of said object so that all difference frequencies between the frequencies f1, f2, f1'' and f2'', other than the difference frequency (f1'' - f2) are outside the range of response of said detector and said oscilloscope.
Claim 3
Dependent Claim
112 words
A velocity measurement system according to claim 1 wherein said two-frequency laser includes end mirrors, an internal gain medium between said mirrors, and first and second individual passive internal etalons between said gain medium and one of said mirrors; said mirrors, said internal gain medium and said etalons being coaxial; said laser being operable to generate beams that are characteristic of said gain medium, the separation of the partially reflective ends of said etalons and of the separation of the mirrors; all said beams combining to produce gain peaks within said two-frequency laser to produce said light at said first and second freqencies f1 and f2 for emission from said two-frequency laser.
Claim 4
Dependent Claim
112 words
A velocity measurement system according to claim 1 wherein said two-frequency laser includes end mirrors, an internal gain medium between said end mirrors, a passive single fixed length of glass between said internal gain medium and one of said mirrors, said mirrors, internal gain medium and length of glass being coaxial, said laser being operable to generate beams that are characteristic of said gain medium, the length of said single fixed length of glass and of the separation of said mirrors, all said beams being combined to produce gain peaks within said two-frequency laser to produce light at said first and second frequencies f1 and f2 for emission from said two-frequency laser.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |