US5200793A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Range finding array camera
Assignee: Kaman Aerospace Corp
•
Filing: 1992-02-20
•
Granted: 1993-04-06
•
Expires: 2012-02-20
Abstract
Abstract An electro-optical camera system is presented. In accordance with the present invention, a light source (e.g. laser) is modulated by an electro-optic modulator (such as a Pockels cell) and transmitted out through an optical system toward a static target scene. The light backscattered from the target scene is then focused by the same optics back through the same Pockels cell onto a two-dimensional array camera such as a CCD or a CID (charge-couple device or charge injection device). A computer determines the frequency modulation period of each pixel in the array as the frequency of the electro-optic modulator is varied. This period is inversely proportional to the range of the target in the direction defined by the pixel location. Thus, all three spatial coordinates (two angles and a range) of each target area sensed by each pixel are determined. The computer will display the array of range data using a suitable output device such as a video display unit or a printer.
Inventors
- 👤 Bobby L. Ulich
- 👤 Kent Pflibsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:34
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/88; G01S17/89; G01S17/02; G01S17/06; G01S17/08; G01S17/32
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
168 words
An electro-optical camera system comprising: light source means; light beam modulating means in communication with said light source means for modulating light received from said light source means; optical focusing means for directing said modulated light through a medium and at a target and for receiving light backscattered from said target and directing said backscattered light through said light beam modulating means wherein said light beam modulating means modulates said backscattered light; photodetector means having a plurality of pixels, said photodetector means for receiving said backscattered light from said light beam modulating means and detecting at least three intensity levels associated with a period of modulation back through said light beam modulating means for each of said pixels; frequency modulating means for varying the frequency of modulation of said light beam modulating means; and computer means for determining the frequency modulation period at each of said pixels as the frequency of modulation of said light beam modulating means is varied wherein range data of the target is determined.
Claim 2
Dependent Claim
168 words
An electro-optical camera system comprising: light source means; light beam modulating means in communication with said light source means for modulating light received from said light source means; optical focusing means for directing said modulated light through a medium and at a target and for receiving light backscattered from said target and directing said backscattered light through said light beam modulating means wherein said light beam modulating means modulates said backscattered light; photodetector means having a plurality of pixels, said photodetector means for receiving said backscattered light from said light beam modulating means and detecting at least three intensity levels associated with a period of modulation back through said light beam modulating means for each of said pixels; frequency modulating means for varying the frequency of modulation of said light beam modulating means; and computer means for determining the frequency modulation period at each of said pixels as the frequency of modulation of said light beam modulating means is varied wherein range data of the target is determined.
Claim 3
Dependent Claim
13 words
The camera of claim 1 including: output means for displaying said range data.
Claim 4
Dependent Claim
14 words
The camera of claim 1 wherein: said range data defines a three dimensional image.
Claim 5
Dependent Claim
12 words
The camera of claim 1 wherein: said light source comprises a laser.
Claim 6
Dependent Claim
80 words
The camera of claim 1 including: beamsplitter means; wave plate means in communication with said beamsplitter means; and wherein said beamsplitter means and said wave plate means are optically positioned between said light source means and said light beam modulating means and wherein light from said light source means is transmitted through said beamsplitter means and said wave plate means and wherein said backscattered light is transmitted through said beamsplitter means and said wave plate means to said photodetector means.
Claim 7
Dependent Claim
23 words
The camera of claim 5 wherein: said wave plate means rotates the polarization of the transmitted light by 45 degrees on each pass.
Claim 8
Dependent Claim
14 words
The camera of claim 5 wherein: said beamsplitter means comprises a polarizing beam splitter.
Claim 9
Dependent Claim
20 words
The camera of claim 5 including: a beam expander optically positioned between said light source means and said beamsplitter means.
Claim 10
Dependent Claim
19 words
The camera of claim 5 including: bandpass filter means optically positioned between said photodetector means and said beamsplitter means.
Claim 11
Dependent Claim
14 words
The camera of claim 1 wherein: said light beam modulating means modulates light sinusoidally.
Claim 12
Dependent Claim
15 words
The camera of claim 1 wherein: said photodetector means comprises a two dimensional array camera.
Claim 13
Dependent Claim
14 words
The camera of claim 1 wherein: said optical focusing means comprises an objective lens.
Claim 14
Dependent Claim
51 words
The camera of claim 11 including: video amplifier means for amplifying video signals from said two dimensional camera, said video amplifier means communicating with said photodetector means; and video digitizer means for digitizing said amplified video signals, said video digitizer means communicating between said video amplifier means and said computer means.
Claim 15
Dependent Claim
16 words
The camera of claim 1 wherein: said frequency modulating means comprises a variable radio frequency oscillator.
Claim 16
Dependent Claim
102 words
The camera of claim 26 wherein: said computer means fits the illuminance of each pixel using the equation: <I.sub.w (i,j)>=I.sub.O (i,j)+I.sub.l (i,j).cos(ω.sub.RF.2Rn/c)(1) where I w (i,j) is the instantaneous illuminance of the pixel at row i and column j in the said photodetector means; <I w (i,j)>is the time averaged value of I w (i,j); I O (i,j) and I l (i,j) are constants; ω RF is the light beam modulating means frequency; n is the index of refraction of the medium; c is the speed of light in a vacuum; and R is the range from the camera to the target.
Claim 17
Dependent Claim
39 words
The camera of claim 15 wherein: said light beam modulating means modulates light received from said light source means by cos (ω RF t) and modulates backscattered light by cos (ω RF (t-τ)) where: τ=2Rn/c; and t=time in seconds;
Claim 18
Dependent Claim
38 words
The camera of claim 16 wherein: said computer means applies a least squares curve fitting algorithm to previously measured pixel illuminance data for at least three known values of modulator frequency to determine Io, I l and τ.
Claim 19
Dependent Claim
15 words
The camera of claim 17 wherein: each of said range values is determined by: R(i,j)=(c/2n)τ(i,j).
Claim 20
Dependent Claim
14 words
The camera of claim 1 wherein: said light beam modulating means comprises electro-optic modulator.
Claim 21
Dependent Claim
14 words
The camera of claim 19 wherein: said electro-optic modulator comprises a Pockels cell means.
Claim 22
Dependent Claim
43 words
The camera of claim 1 including: light source beam splitter means optically positioned between said light source means and said light beam modulating means, said light source beam splitter means producing an array of beams for illuminating selected areas of a target scene.
Claim 23
Independent Claim
112 words
A method for providing range data of a target using an electro-optical camera system including the steps of: generating a light beam; modulating the light beam using a light beam modulator; directing the modulating light beam through a medium and at a target; receiving light backscattered from the target and directing the backscattered light back through said light beam modulator wherein the received backscattered light is modulated; detecting at least three intensity levels associated with a period of modulation back through said light beam modulator for each of a plurality of pixels; and converting said period associated with said intensity levels at each of said pixels into range data of the target.
Claim 24
Independent Claim
112 words
A method for providing range data of a target using an electro-optical camera system including the steps of: generating a light beam; modulating the light beam using a light beam modulator; directing the modulating light beam through a medium and at a target; receiving light backscattered from the target and directing the backscattered light back through said light beam modulator wherein the received backscattered light is modulated; detecting at least three intensity levels associated with a period of modulation back through said light beam modulator for each of a plurality of pixels; and converting said period associated with said intensity levels at each of said pixels into range data of the target.
Claim 25
Dependent Claim
21 words
The method of claim 22 including the step of: converting said range data to a three dimensional image of the target.
Claim 26
Independent Claim
121 words
An apparatus for providing range data of a target using an electro-optical camera system including: means for generating a light beam; means for modulating the light beam using a light beam modulator; means for directing the modulated light beam through a medium and at a target; means for receiving light backscattered from the target and directing the backscattered light back through said light beam modulator wherein the received backscattered light is modulated; means for detecting at least three intensity levels associated with a period of modulation back through said light beam modulator for each of a plurality of pixels; and means for converting said period associated with said intensity levels at each of said pixels into range data of the target.
Claim 27
Independent Claim
121 words
An apparatus for providing range data of a target using an electro-optical camera system including: means for generating a light beam; means for modulating the light beam using a light beam modulator; means for directing the modulated light beam through a medium and at a target; means for receiving light backscattered from the target and directing the backscattered light back through said light beam modulator wherein the received backscattered light is modulated; means for detecting at least three intensity levels associated with a period of modulation back through said light beam modulator for each of a plurality of pixels; and means for converting said period associated with said intensity levels at each of said pixels into range data of the target.
Claim 28
Dependent Claim
20 words
The apparatus of claim 24 including: means for converting said range data to a three dimensional image of the target.
Claim 29
Dependent Claim
27 words
The camera of claim 1 wherein: said range data comprises a plurality of range values, each one of said range values corresponding to one of said pixels.
References Cited (Backward Citations)
US3649123A
Cited
US3644042A
Cited
US3733129A
Cited
US3901597A
Cited
US4167329A
Cited
US4721385A
Cited
US5006813A
Cited
US4928152A
Cited
US4950075A
Cited
US4935616A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-05 | 1996-10-05 | 1997-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-05 | 2000-10-05 | 2001-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-05 | 2004-10-05 | 2005-04-06 | $7700.00 | Window Closed / Lapsed |