Ladar sensor for landing, docking and approach
First Claim
Patent Images
1. A ladar sensor comprising:
- an adaptive controller with at least one control output,a detector array bias voltage control circuit which varies a bias voltage in response to said at least one control output of said adaptive controller,a pulsed laser transmitter with an optical axis and pulsed laser light output and transmitting optics for illuminating a scene in the field of view with a pattern of light intensity,a system controller for initiating the pulsing of said pulsed laser transmitter,receive optics boresighted along said optical axis for collecting and conditioning an optical signal consisting of pulsed laser light reflected from said scene in the field of view,a detector array comprised of a plurality of light detecting pixels, said detector array disposed to intercept said collected and conditioned optical signal from said receive optics, and each of said light detecting pixels in said detector array intercepting a pixelated portion of aforesaid optical signal consisting of pulsed laser light reflected from said scene in the field of view, and each light detecting pixel with an electrical output producing an electrical output signal with an associated optoelectronic conversion gain, said detector array responsive to the bias voltage lowering the optoelectronic conversion gain of avalanche photodiodes comprising the light detecting pixels of the detector array thereby avoiding saturation as a docking target is approached,a plurality of unit cell electrical circuits disposed on a readout integrated circuit, and each unit cell electrical circuit with an input connected to one of said electrical outputs of said plurality of light detecting pixels, and each unit cell electrical circuit with an output,a plurality of unit cell timing circuits, each of the said plurality of unit cell timing circuits connected to an output of a said unit cell electrical circuit, and each of said unit cell timing circuits having an output, and each unit cell timing circuit initiated by a master start signal indicating the start of a laser light pulse emanating from said pulsed laser transmitter,a unit cell timing circuit termination signal which stops the counting of at least one of the said unit cell timing circuits,and, a readout circuit for reading out the outputs of said unit cell electrical circuits and unit cell timing circuits.
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Abstract
A system for landing or docking a mobile platform is enabled by a flash LADAR sensor having an adaptive controller with Automatic Gain Control (AGC). Range gating in the LADAR sensor penetrates through diffuse reflectors. The LADAR sensor adapted for landing/approach comprises a system controller, pulsed laser transmitter, transmit optics, receive optics, a focal plane array of detectors, a readout integrated circuit, camera support electronics and image processor, an image analysis and bias calculation processor, and a detector array bias control circuit. The system is capable of developing a complete 3-D scene from a single point of view.
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Citations
19 Claims
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1. A ladar sensor comprising:
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an adaptive controller with at least one control output, a detector array bias voltage control circuit which varies a bias voltage in response to said at least one control output of said adaptive controller, a pulsed laser transmitter with an optical axis and pulsed laser light output and transmitting optics for illuminating a scene in the field of view with a pattern of light intensity, a system controller for initiating the pulsing of said pulsed laser transmitter, receive optics boresighted along said optical axis for collecting and conditioning an optical signal consisting of pulsed laser light reflected from said scene in the field of view, a detector array comprised of a plurality of light detecting pixels, said detector array disposed to intercept said collected and conditioned optical signal from said receive optics, and each of said light detecting pixels in said detector array intercepting a pixelated portion of aforesaid optical signal consisting of pulsed laser light reflected from said scene in the field of view, and each light detecting pixel with an electrical output producing an electrical output signal with an associated optoelectronic conversion gain, said detector array responsive to the bias voltage lowering the optoelectronic conversion gain of avalanche photodiodes comprising the light detecting pixels of the detector array thereby avoiding saturation as a docking target is approached, a plurality of unit cell electrical circuits disposed on a readout integrated circuit, and each unit cell electrical circuit with an input connected to one of said electrical outputs of said plurality of light detecting pixels, and each unit cell electrical circuit with an output, a plurality of unit cell timing circuits, each of the said plurality of unit cell timing circuits connected to an output of a said unit cell electrical circuit, and each of said unit cell timing circuits having an output, and each unit cell timing circuit initiated by a master start signal indicating the start of a laser light pulse emanating from said pulsed laser transmitter, a unit cell timing circuit termination signal which stops the counting of at least one of the said unit cell timing circuits, and, a readout circuit for reading out the outputs of said unit cell electrical circuits and unit cell timing circuits. - View Dependent Claims (2, 3, 4, 5)
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6. A ladar sensor comprising:
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an adaptive controller with at least one control output which controls a range gate which has a start time and a duration, a pulsed laser transmitter with an optical axis and pulsed laser light output and transmitting optics for illuminating a scene in the field of view with a pattern of light intensity, a system controller for initiating the pulsing of said pulsed laser transmitter, receive optics boresighted along said optical axis for collecting and conditioning an optical signal consisting of pulsed laser light reflected from said scene in the field of view, a detector array comprised of a plurality of light detecting pixels, said detector array disposed to intercept said collected and conditioned optical signal from said receive optics, and each of said light detecting pixels in said detector array intercepting a pixelated portion of aforesaid optical signal consisting of pulsed laser light reflected from said scene in the field of view, and each light detecting pixel with an electrical output producing an electrical output signal with an associated optoelectronic conversion gain, said detector array responsive to a bias voltage lowering the optoelectronic conversion gain of avalanche photodiodes comprising the light detecting pixels of the detector array thereby avoiding saturation as a docking target is approached, a plurality of unit cell electrical circuits disposed on a readout integrated circuit, and each unit cell electrical circuit with an input connected to one of said electrical outputs of said plurality of light detecting pixels, and each unit cell electrical circuit with an electrical output signal, a plurality of unit cell timing circuits, each of the said plurality of unit cell timing circuits connected to an output of a said unit cell electrical circuit, and each of said unit cell timing circuits having an output, and each unit cell timing circuit initiated by a master start signal indicating the start of a laser light pulse emanating from said pulsed laser transmitter, a unit cell timing circuit termination signal which stops the counting of at least one of the said unit cell timing circuits, a readout circuit for reading out the electrical output signals of said unit cell electrical circuits and unit cell timing circuits, and, a range gate which rejects certain of said electrical output signals from said unit cell electrical circuits resident on said readout integrated circuit which occur in time prior to a range gate start time. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A cooperative landing system designator comprised of a designating laser and pointing system mounted on a designator platform, and a receive only ladar sensor mounted on a guided aircraft, said receive only ladar sensor further comprising:
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receive optics for collecting and conditioning an optical signal consisting of pulsed laser light reflected from a scene in the field of view, a detector array comprised of a plurality of light detecting pixels, said detector array disposed to intercept said collected and conditioned optical signal from said receive optics, and each of said light detecting pixels in said detector array intercepting a pixelated portion of aforesaid optical signal consisting of pulsed laser light reflected from said scene in the field of view, and each light detecting pixel with an electrical output producing an electrical output signal with an associated optoelectronic conversion gain, said detector array responsive to a bias voltage lowering the optoelectronic conversion gain of avalanche photodiodes comprising the light detecting pixels of the detector array thereby avoiding saturation as a docking target is approached, a plurality of unit cell electrical circuits disposed on a readout integrated circuit, and each unit cell electrical circuit with an input connected to one of said electrical outputs of said plurality of light detecting pixels, and each unit cell electrical circuit with an output, a plurality of unit cell timing circuits, each of the said plurality of unit cell timing circuits connected to an output of a said unit cell electrical circuit, and each of said unit cell timing circuits having an output, and each unit cell timing circuit initiated by a master start signal indicating the start of an observation time period, a unit cell timing circuit termination signal which stops the counting of at least one of the said unit cell timing circuits, and, a readout circuit for reading out the outputs of said unit cell electrical circuits and unit cell timing circuits. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification