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US 5,335,070 AGranted
Laser light beam homogenizer and imaging lidar system incorporating same
AssigneeKaman Aerospace Corporation
InventorsKent P. Pflibsen, Albert N. Stuppi
Life of this patent
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Abstract
A new and improved laser light beam homogenizer for transforming a laser beam with spatially inhomogeneous intensity into a beam with a more nearly spatially uniform intensity pattern is presented. The light beam is diverged by a lens and presented to an integrator. The integrator transforms the beam into a beam with a more uniform illumination. The uniform illumination beam is then impinged on control optics to limit the divergence of the uniform beam and control higher order distortion in the system. This beam may then be illuminated at a predetermined distance by a projecting optic lens. The laser light beam homogenizer of this invention is particularly well suited for use in an imaging lidar system.
Claims16
An apparatus for detecting and imaging an object at least partially enveloped by a backscattering medium which is at least partially transmitting to light comprising:
- light pulse generating means for selectively generating short pulses of light;
- light projection means for receiving said pulses of light from said light pulse generating means and transforming the cross-section of said light pulse from a first shape to a preselected second shape;
- projecting means for projecting said short pulses of light toward the backscattering medium and at an object enveloped by the medium;
- camera means for detecting said pulses of light reflected back from said object after a time delay corresponding to the round-trip propagation time of said light pulses to and from said object;
- and
- converting means for converting said detected pulses of light to a video image of said object;
- said light projection means comprising;
- diverging means for diverging a light beam with spatially inhomogeneous intensity, said light having a coherence length L.sub.C, said diverging means providing a diverging light beam;
- integrator means having a first aperture for receiving said diverging light beam and having a plurality of internally reflective surfaces for forming an array of apparent light sources, the light from each apparent source in said array being superposed by said integrator means at a second aperture thereof, each individual light ray from each apparent source following a distinct light path to said second aperture to provide a uniform illumination beam;
- minimum path length difference means for providing a minimum path length difference between the individual path lengths of any two rays coincident at said second aperture and arising from adjacent apparent sources in said array, said minimum path length difference means being at least said coherence length L.sub.C of said beam;
- control optics means for receiving said uniform illumination beam, said control optics means reducing the divergence of said uniform illumination beam and providing a controlled beam;
- and
- projection optics means for projecting an image of the integrator to the desired distance.
10 more elements
An apparatus for detecting and imaging an object at least partially enveloped by a backscattering medium which is at least partially transmitting to light comprising:
- light pulse generating means for selectively generating short pulses of light;
- light projection means for receiving said pulses of light from said light pulse generating means and transforming the cross-section of said light pulse from a first shape to a preselected second shape;
- projecting means for projecting said short pulses of light toward the backscattering medium and at an object enveloped by the medium;
- camera means for detecting said pulses of light reflected back from said object after a time delay corresponding to the round-trip propagation time of said light pulses to and from said object;
- and
- converting means for converting said detected pulses of light to a video image of said object;
- said light projection means comprising;
- diverging means for diverging a light beam with spatially inhomogeneous intensity, said light beam having a coherence length L.sub.C, said diverging means providing a diverging light beam;
- integrator means having a first aperture for receiving said diverging light beam and having a plurality of movable internally reflective surfaces for forming an array of apparent light sources, the light from each apparent source in said array being superposed by said integrator means at a second aperture thereof, each individual light ray from each apparent source following a distinct light path to said second aperture to provide a uniform illumination beam;
- means for moving said movable internally reflective surface to control the aspect ratio of said uniform illumination beam;
- and
- minimum path length difference means for providing a minimum path length difference between the individual path lengths of any two rays coincident at said second aperture and arising from adjacent apparent sources in said array, said minimum path length difference means being at least said coherence length L.sub.C of said light beam.
9 more elements
An apparatus for detecting and imaging an object at least partially enveloped by a backscattering medium which is at least partially transmitting to light comprising:
- light pulse generating means for selectively generating short pulses of light;
- light projection means for receiving said pulses of light from said light pulse generating means and transforming the cross-section of said light pulse from a first shape to a preselected second shape;
- projecting means for projecting said short pulses of light toward the backscattering medium and at an object enveloped by the medium;
- camera means for detecting said pulses of light reflected back from said object after a time delay corresponding to the round-trip propagation time of said light pulses to and from said object;
- and
- converting means for converting said detected pulses of light to a video image of said object;
- said light projection means comprising;
- diverging means for diverging a light beam with spatially inhomogeneous intensity, said light having a coherence length L.sub.C, said diverging means providing a diverging light beam;
- integrator means having a first aperture for receiving said diverging light beam and having a plurality of internally reflective surfaces for forming an array of apparent light sources, the light from each apparent source in said array being superposed by said integrator means at a second aperture thereof, each individual light ray from each apparent source following a distinct light path to said second aperture to provide a uniform illumination beam;
- control optics means for receiving said uniform illumination beam, said control optics means reducing the divergence of said uniform illumination beam and providing a controlled beam;
- and
- projection optics means for projecting an image of the integrator to the desired distance.
9 more elements
An apparatus for detecting and imaging an object at least partially enveloped by a backscattering medium which is at least partially transmitting to light comprising:
- light pulse generating means for selectively generating short pulses of light;
- light projection means for receiving said pulses of light from said light pulse generating means and transforming the cross-section of said light pulse from a first shape to a preselected second shape;
- projecting means for projecting said short pulses of light toward the backscattering medium and at an object enveloped by the medium;
- camera means for detecting said pulses of light reflected back from said object after a time delay corresponding to the round-trip propagation time of said light pulses to and from said object;
- and
- converting means for converting said detected pulses of light to a video image of said object;
- said light projection means comprising;
- diverging means for diverging a light beam with spatially inhomogeneous intensity, said light beam having a coherence length L.sub.C, said diverging means providing a diverging light beam;
- integrator means having a first aperture for receiving said diverging light beam and having a plurality of movable internally reflective surfaces for forming an array of apparent light sources, the light from each apparent source in said array being superposed by said integrator means at a second aperture thereof, each individual light ray from each apparent source following a distinct light path to said second aperture to provide a uniform illumination beam;
- and means for moving said movable internally reflective surface control the aspect ratio of said uniform illumination beam.
7 more elements
The laser light beam homogenizer of 1 wherein said diverging means comprises:
- a positive lens being positioned at a distanced from said first aperture of said integrator means, whereby said light beam converges to a focal point and then diverges so that substantially all of the extreme rays of said diverging light beam are received by said first aperture.
Dependencies are inferred from the claim text.