Laser velocimeter
First Claim
1. A method for determining velocity of an object relative to particles in a gaseous mass surrounding said object, said method comprising the steps of:
- (a) projecting a plurality of pairs of beams of optical radiation from said object to a measurement volume that is spaced apart from said object, each pair of said plurality of pairs of beams consisting of two beams that are generally ribbon-shaped and substantially parallel to each other and that are separated from each other by a predetermined distance at the measurement volume, the two beams of each pair of said plurality of pairs of beams being nonparallel to the beams of every other pair of said plurality of pairs of beams at the measurement volume, the particles in said gaseous mass at the measurement volume scattering optical radiation from the two beams of each pair of said plurality of pairs of beams;
(b) gathering a portion of the optical radiation scattered by said particles in said gaseous mass surrounding said object from the two beams of each pair of said plurality of pairs of beams at the measurement volume;
(c) discriminating the gathered optical radiation scattered from each of the two beams of each pair of said plurality of pairs of beams at the measurement volume from the gathered optical radiation scattered from every other beam of said plurality of pairs of beams at the measurement volume;
(d) generating a plurality of pairs of electrical signals, each electrical signal being related to the scattering of optical radiation from a corresponding beams of said plurality of pairs of beams at the measurement volume;
(e) processing said plurality of pairs of electrical signals to measure time intervals required for said particles to traverse the predetermined distance between the two beams of each pair of said plurality of pairs of beams at the measurement volume, and to calculate components of velocity of said particles relative to said object; and
(f) determining a velocity vector for said object relative to said particles from said calculated components of velocity.
1 Assignment
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Accused Products
Abstract
An aircraft velocimeter comprises means for projecting three pairs of independently generated ribbon-shaped laser beams to a measurement volume located at a predetermined distance from the aircraft with a predetermined separation being maintained between the two ribbon-shaped laser beams of each pair at the measurement volume. The times of flight of atmospheric aerosol particles between the two ribbon-shaped laser beams of corresponding pairs of laser beams are measured as the aerosol particles pass through the measurement volume. From the predetermined distance between the two ribbon-shaped laser beams of each pair and the measured time of flight of an aerosol particle across that predetermined distance, a component of velocity of the aerosol particle relative to the aircraft is calculated for each pair of ribbon-shaped laser beams. From the three components of velocity corresponding to the three pairs of ribbon-shaped laser beams projected to the measurement volume, a vector measurement of the velocity of the aircraft relative to atmospheric particles in the surrounding atmosphere is obtained using an on-board computer programmed with a conventional algorithm.
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Citations
41 Claims
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1. A method for determining velocity of an object relative to particles in a gaseous mass surrounding said object, said method comprising the steps of:
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(a) projecting a plurality of pairs of beams of optical radiation from said object to a measurement volume that is spaced apart from said object, each pair of said plurality of pairs of beams consisting of two beams that are generally ribbon-shaped and substantially parallel to each other and that are separated from each other by a predetermined distance at the measurement volume, the two beams of each pair of said plurality of pairs of beams being nonparallel to the beams of every other pair of said plurality of pairs of beams at the measurement volume, the particles in said gaseous mass at the measurement volume scattering optical radiation from the two beams of each pair of said plurality of pairs of beams; (b) gathering a portion of the optical radiation scattered by said particles in said gaseous mass surrounding said object from the two beams of each pair of said plurality of pairs of beams at the measurement volume; (c) discriminating the gathered optical radiation scattered from each of the two beams of each pair of said plurality of pairs of beams at the measurement volume from the gathered optical radiation scattered from every other beam of said plurality of pairs of beams at the measurement volume; (d) generating a plurality of pairs of electrical signals, each electrical signal being related to the scattering of optical radiation from a corresponding beams of said plurality of pairs of beams at the measurement volume; (e) processing said plurality of pairs of electrical signals to measure time intervals required for said particles to traverse the predetermined distance between the two beams of each pair of said plurality of pairs of beams at the measurement volume, and to calculate components of velocity of said particles relative to said object; and (f) determining a velocity vector for said object relative to said particles from said calculated components of velocity. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for determining velocity of an object relative to particles in a gaseous mass surrounding said object, said apparatus comprising:
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(a) means for projecting a plurality of pairs of beams of optical radiation from said object to a measurement volume that is spaced apart from said object, each pair of said plurality of pairs of beams consisting of two beams that are generally ribbon-shaped and substantially parallel to each other and that are separated from each other by a predetermined distance at the measurement volume, the two beams of each pair of said plurality of pairs of beams being nonparallel to the beams of every other pair of said plurality of pairs of beams at the measurement volume, the particles in said gaseous mass at the measurement volume thereby scattering optical radiation from the two beams of each pair of said plurality of pairs of beams; (b) means for gathering a portion of the optical radiation scattered by said particles in said gaseous mass surrounding said object from the two beams of each pair of said plurality of pairs of beams at the measurement volume; (c) means for discriminating the gathered optical radiation scattered from each of the two beams of each pair of said plurality of pairs of beams at the measurement volume from the gathered optical radiation scattered from every other beam of said plurality of pairs of beams at the measurement volume; (d) means for generating a plurality of pairs of electrical signals, each electrical signal being related to the scattering of optical radiation from a corresponding beam of said plurality of pairs of beams at the measurement volume; (e) means for processing said plurality of pairs of electrical signals to measure time intervals required for said particles to traverse the predetermined distance between the two parallel beams of each pair of said plurality of pairs of beams at the measurement volume, and to calculate components of velocity of said particles relative to said object; and (f) means for determining a velocity vector for said object relative to said particles from said calculated components of velocity. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An apparatus mountable on an aircraft for measuring velocity of said aircraft relative to atmospheric aerosol particles in an air mass surrounding said aircraft, said apparatus comprising:
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(a) means for generating three pairs of ribbon-shaped laser beams; (b) means for focussing said three pairs of ribbon-shaped laser beams onto an intermediate focal surface to form three corresponding pairs of intermediate focal surface to form three corresponding pairs of intermediate image, the intermediate images formed by the two beams of each pair of said ribbon-shaped laser beams being separated from each other on said intermediate focal surface by a specified distance; (c) means for expanding said three pairs of ribbon-shaped laser and for focussing the expanded beams onto a projection surface in a measurement volume located at a predetermined distance from said aircraft, so that the two beams of each pair of said ribbon-shaped laser beams are substantially parallel to each other at the measurement volume, and so that the images formed on the projection surface by the two beams of each pair of said ribbon-shaped laser beams are separated from each other by a distance that is related to the separation between the corresponding intermediate images formed by the two beams of the same pair of said ribbon-shaped laser beams on the intermediate focal surface in accordance with a predetermined magnification ratio, the two beams of each pair of said ribbon-shaped laser beams being nonparallel to the beams of each of the other pairs of said ribbon-shaped laser beams at the measurement volume, aerosol particles in said measurement volume scattering light from the two beams of each pair of said ribbon-shaped laser beams; (d) means for gathering a portion of the light scattered by said aerosol particles in said measurement volume from the two beams of each pair of said ribbon-shaped laser beams; (e) a field stop plate having three pairs of field stops, said field stops being positioned with respect to each other on a field stop array surface so that each field stop can transmit the scattered light that has been gathered from a corresponding one of said ribbon-shaped laser beams, each field stop thereby discriminating the scattered light that has been gathered from the corresponding one of said ribbon-shaped laser beams from the scattered light that has been gathered from every other one of said ribbon-shaped laser beams; (f) means for generating three pairs of electrical signals, each electrical signal being responsive to scattered light gathered from the corresponding one of said ribbon-shaped laser beams and transmitted by a corresponding one of said field stops; (g) means for processing said three pairs of electrical signals to measure time intervals required for said aerosol particles to traverse the distance between the two parallel beams of each pair of said ribbon-shaped laser beams at the measurement volume, and to calculate velocity components in three dimensions for said aerosol particles relative to said aircraft; and (h) means for determining a velocity vector for said aircraft relative to said aerosol particles from said calculated velocity components. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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- 36. A collimating lens system comprising five lens elements configured and positioned with respect to each other along an optic axis according to an optical prescription substantially as follows
- space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 0 ∞
1.58 Air 1 -11.549 10.77 LAFN2 1.731759 2 -8.128 0.24 Air 3 36.309 1.92 SF3 1.721101 4 13.927 4.38 BAK1 1.565285 5 -18.720 1.34 Air 6 56.060 1.92 SF3 1.721101 7 9.390 4.38 BAK1 1.565285 8 -298.400 4.27 Air 9 ∞
Air ______________________________________
where optically significant surfaces of said collimator group in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No.";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thicknesses of lens element and spacings bounded by adjacent surfaces in said direction of propagation of light;
where positive and negative designations for the radii corresponding to positive and negative curvature of the surfaces;
where entries in the column headed "Material" identify air gap spacings that are bounded by corresponding adjacent surfaces by the designation "Air", and identify optical glass lens elements that are bounded by corresponding adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (measured)" provides refractive index values with reference to a base wavelength of 0.83 micron a supplied by the optical glass manufacturer. - space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 0 ∞
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37. An anamorphic beam-expander lens system comprising five lens elements configured and positioned with respect to each other along an optic axis according to an optical prescription substantially as follows:
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space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 1 -9.000 2.000 SF11 1.763321 2 ∞
1.000 Air 3 -9.000 2.000 SF11 1.763321 4 ∞
4.305 Air 5 -34.595 1.600 LF7 1.564422 6 ∞
3.000 PSK3 1.545105 7 -11.078 0.500 Air 8 ∞
3.000 PSK3 1.545105 9 -20.487 Air ______________________________________where optically significant surfaces of said beam-expander group in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No.";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thickness of lens elements and spacings bounded by adjacent surfaces in said direction of propagation of light;
where positive and negative designations for the radii correspond to positive and negative curvatures of the surfaces;
where entries in the column headed "Material" identify air gap spacings that are bounded by corresponding adjacent surfaces by the designation "Air", and identify optical glass lens elements that are bounded by corresponding adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (measured)" provides refractive index values with reference to a base wavelength of 0.83 micron as supplied by the optical glass manufacturer.
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38. An imaging lens system comprising three lens elements configured and positioned with respect to each other along an optic axis according to an optical prescription substantially as follows:
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space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 1 46.563 4.000 SK11 1.556329 2 -30.940 2.000 SF4 1.735245 3 -1172.490 0.250 Air 4 33.561 3.500 BK7 1.510288 5 -680.212 (to image) Air 6 ∞
Air (image surface) ______________________________________where optically significant surfaces of said imager group in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No.";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thickness of lens elements and spacings bounded by adjacent surfaces in said direction of propagation of light;
where positive and negative designations for the radii correspond to positive and negative curvatures of the surfaces;
where entries in the column headed "Material" identify air gap spacings that are bounded by corresponding adjacent surfaces by the designation "Air", and identify optical glass lens elements that are bounded by corresponding adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (measured)" provides refractive index values with reference to a base wavelength of 0.83 micron a supplied by the optical glass manufacturer.
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39. A magnifying lens system comprising two lens elements configured and positioned with respect to each other along an optical axis according to an optical prescription substantially as follows:
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space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 1 467.256 5.000 SF1 1.699628 2 117.490 0.500 Air 3 117.490 9.500 SK11 1.556329 4 -164.160 (to image) Air ______________________________________where surfaces of said two lens elements in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No.";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thickness of said two lens elements and of an intervening air gap bounded by corresponding adjacent surfaces in said direction air gap bounded by corresponding adjacent surfaces in said direction of propagation of light;
where positive and negative designations for the radii correspond to positive and negative curvatures of the surfaces;
where entries in the column headed "Material" identify optical glass lens elements that are bounded by adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (measured)" provides refractive index values with reference to a base wavelength of 0.83 micron as supplied by the optical glass manufacturer.
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40. An imaging lens system comprising three lens elements configured and positioned with respect to each other along an optic axis according to an optical prescription substantially as follows:
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space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (measured) ______________________________________ 0 ∞
2450.708 Air 1 229.283 24.000 BK7 1.509924 2 -589.788 0.500 Air 3 193.853 26.880 BK7 1.509924 4 -309.321 0.800 Air 5 -314.091 12.500 SF6 1.783366 6 507.365 264.202 Air ______________________________________where optically significant surfaces of aid collimator group in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No.";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thicknesses of lens element and spacings bounded by adjacent surfaces in said direction of propagation o light;
where positive and negative designations for the radii correspond to positive and negative curvatures of the surfaces;
where entries in the column headed "Material" identify air gap spacings that are bounded by corresponding adjacent surfaces by the designation "Air", and identify optical glass lens elements that are bounded by corresponding adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (measured)" provides refractive index values with reference to a base wavelength of 0.83 micron a supplied by the optical glass manufacturer.
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41. A relay lens system comprising a plurality of lens elements configured and positioned with respect to each other along an optic axis according to a optical prescription substantially as follows:
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space="preserve" listing-type="tabular">______________________________________ Surface Radius Thickness No. (mm) (mm) Material N.sub..83 (catalog) ______________________________________ 0 ∞
3.635 Air 1 -18.217 2.500 SF14 1.741403 2 18.217 4.550 BK7 1.510206 3 -5.931 5.500 Air 4 46.010 2.000 SF14 1.741403 5 14.940 4.350 BK7 1.510206 6 -14.940 1.000 Air 7 ∞
2.000 BK7 1.510206 8 ∞
1.000 Air 9 48.750 3.485 BK7 1.510206 10 -14.285 1.567 Air 11 -11.146 1.600 SF4 1.735580 12 -41.135 6.391 Air 13 11.557 3.840 K10 1.494296 14 -11.557 2.000 SF6 1.782732 15 -19.431 3.178 Air 16 4.770 3.907 LAFN2 1.731382 17 6.840 0.500 Air 18 ∞
1.200 K10 1.494296 19 ∞
1.142 Air 20 (Image) ______________________________________where optically significant surfaces of said collimator group in the direction of propagation of light along said optic axis are numbered consecutively in the column headed "Surface No";
where the columns headed "Radius" and "Thickness" provide axial radii of curvature and thicknesses of lens element and spacings bounded by adjacent surfaces in said direction of propagation o light;
where positive and negative designations for the radii correspond to positive and negative curvatures of the surfaces;
where entries in the column headed "Material" identify air gap spacings that are bounded by corresponding adjacent surfaces by the designation "Air", and identify optical glass lens elements that are bounded by corresponding adjacent surfaces by manufacturer'"'"'s designations; and
where the column headed "N.sub..83 (catalog)" provides refractive index values as supplied by the optical glass manufacturer for a nominal operating wavelength of 0.83 micron.
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Specification