US3820896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Velocimeter with improved signal to noise ratio
Assignee: Singer Co
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Filing: 1973-01-02
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Granted: 1974-06-28
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Expires: 1993-01-02
Abstract
Abstract An improved laser velocimeter in which both magnitude and sense of direction are provided and which has an improved signal to noise ratio is shown. To obtain sense of direction the conventional laser velocimeter which includes a transmitting beam and a receiver comprising a grating and a photo detector, has added to it a second grating and detector. The second grating being shifted one-quarter of a line pair from that of the first resulting in two outputs which are shifted 90 degrees from each other. This information is processed in a well-known manner to obtain an output indicative of sense of direction. To improve signal to noise ratio a grating is used with the transmitted beam to cause it to form three separate beams which when received through the receiving grating will be superimposed upon each other to cause a greater portion of the signal to be utilized by the detector.
Inventors
- 👤 G Stavis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:05
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/36; G01P3/366; G01S; G01S17/00; G01S17/02; G01S17/50
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
184 words
In a laser velocimeter comprising at least a laser transmitter transmitting a beam to a reflecting surface, a receiving including a first optical grating and first photodetector and means to obtain velocity magnitude from the received signal, apparatus to provide velocity sense and to provide an improved signal to noise ratio comprising: a. lens apparatus adjacent said laser to provide a wider beam; b. a second optical grating placed adjacent to and on the side of said lens apparatus closest the reflecting surface whereby three beams will be transmitted by said laser-transmitter; c. a first lens to image the radiation received by said first grating on the first photo-detector; d. a third grating positioned with the lines thereon a quarter grating cycle from said first grating; e. means to split the received radiation between said first and third gratings; f. a second photo detector; g. a second lens to image the radiation received by said third grating on said second photo detector; and h. means to obtain from the outputs of said first and second detectors a signal indicative of velocity sense of direction.
Claim 2
Dependent Claim
184 words
In a laser velocimeter comprising at least a laser transmitter transmitting a beam to a reflecting surface, a receiving including a first optical grating and first photodetector and means to obtain velocity magnitude from the received signal, apparatus to provide velocity sense and to provide an improved signal to noise ratio comprising: a. lens apparatus adjacent said laser to provide a wider beam; b. a second optical grating placed adjacent to and on the side of said lens apparatus closest the reflecting surface whereby three beams will be transmitted by said laser-transmitter; c. a first lens to image the radiation received by said first grating on the first photo-detector; d. a third grating positioned with the lines thereon a quarter grating cycle from said first grating; e. means to split the received radiation between said first and third gratings; f. a second photo detector; g. a second lens to image the radiation received by said third grating on said second photo detector; and h. means to obtain from the outputs of said first and second detectors a signal indicative of velocity sense of direction.
Claim 3
Dependent Claim
125 words
The invention according to claim 1 wherein said means to obtain said signal indicative of velocity sense comprise: a. a reference oscillator providing first and second outputs of equal frequency but shifted in phase by 90*; b. a first modulator having the output of said first detector as a signal input and said first oscillator signal as a modulation input; c. a second modulator having the output of said second detector as a signal input and the second output of said oscillator as a modulating input; d. means to subtract the outputs of said first and second modulators; e. a sine-cosine tracker having the output of said subtractor and an output of said oscillator as inputs and providing said velocity sense signal as an output.
Claim 4
Dependent Claim
22 words
The invention according to claim 1 and further including aperture stops at the image planes of said first and second photo detectors.
Claim 5
Dependent Claim
18 words
The invention according to claim 1 wherein said means to split said received radiation comprises a beamsplitting mirror.
Claim 6
Dependent Claim
108 words
In a laser velocimeter comprising at least a laser transmitter transmitting a beam to a reflecting surface, a receiver including a first optical grating and photo-detector and means to obtain velocity magnitude from the received signal, apparatus to provide an improved signal to noise ratio in said velocimeter comprising: a. lens apparatus adjacent said laser to provide a wider beam; b. a second optical grating placed adjacent to and on the side of said lens apparatus closest the reflecting surface whereby a plurality of beams will be transmitted by said laser transmitter; and c. a lens to image the radiation received by said first grating onto said photo-detector.
Claim 7
Dependent Claim
108 words
In a laser velocimeter comprising at least a laser transmitter transmitting a beam to a reflecting surface, a receiver including a first optical grating and photo-detector and means to obtain velocity magnitude from the received signal, apparatus to provide an improved signal to noise ratio in said velocimeter comprising: a. lens apparatus adjacent said laser to provide a wider beam; b. a second optical grating placed adjacent to and on the side of said lens apparatus closest the reflecting surface whereby a plurality of beams will be transmitted by said laser transmitter; and c. a lens to image the radiation received by said first grating onto said photo-detector.
Claim 8
Dependent Claim
18 words
The invention according to claim 5 and further including aperture stops at the image planes of said photo-detector.
Claim 9
Dependent Claim
31 words
The invention according to claim 5 wherein said first and second optical grating are identical and said laser transmitter and said receiver are positioned to effect an optical leverage of two.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |