LADAR sensor for a dense environment

A ladar system comprising:

• a first ladar sensor and a second ladar sensor:
• said first ladar sensor having
• a semiconductor laser transmitter with a pulsed laser light output transmitting light with a first pulse width through a diffusing optic for illuminating a scene in a field of view of said first ladar sensor,
• a time zero reference circuit having a time zero reference output, said time zero reference output adapted to signal the beginning of the pulsed laser light transmission,
• receiving optics for collecting and conditioning the pulsed laser light reflected from said scene in the field of view,
• a two dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, and each of said light sensitive detectors with an output producing an electrical pulse from a reflected portion of said pulsed laser light output,
• a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors,
• a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to said clock circuit and another input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical pulse amplifier adapted to amplify the electrical pulses,
• a pulse width discriminator adapted to receive electrical pulses from each unit cell, and to pass through valid electrical pulses of said first pulse width, and to block pulses of other pulse widths,
• a range measuring circuit adapted to measure range for each unit cell based on the number of clock cycles between the time zero reference pulse, and the time of arrival of said valid electrical pulses,
• said second ladar sensor having
• a semiconductor laser transmitter with a pulsed laser light output transmitting light with a second pulse width through a diffusing optic for illuminating a scene in a field of view of said second ladar sensor,
• a time zero reference circuit having a time zero reference output, said time zero reference output adapted to signal the beginning of the pulsed laser light transmission, receiving optics for collecting and conditioning the pulsed laser light reflected from said scene in the field of view,
• a two dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, and each of said light sensitive detectors with an output producing an electrical pulse from a reflected portion of said pulsed laser light output,
• a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors,
• a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to said clock circuit and another input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical pulse amplifier adapted to amplify the electrical pulses,
• a pulse width discriminator adapted to receive electrical pulses from each unit cell, and to pass through valid electrical pulses of said second pulse width, and to block pulses of other pulse widths,
• a range measuring circuit adapted to measure range for each unit cell based on the number of clock cycles between the time zero reference pulse, and the time of arrival of said valid electrical pulses.

A ladar system comprising:

• a first ladar sensor and a second ladar sensor:
• said first ladar sensor having
• a semiconductor laser transmitter with a laser light output transmitting a first coded sequence of light pulses through a diffusing optic for illuminating a scene in a field of view of said first ladar sensor,
• a time zero reference circuit having a time zero reference output, said time zero reference output adapted to signal the beginning of the transmission of the first coded sequence of light pulses,
• receiving optics for collecting and conditioning the coded sequence of light pulses reflected from said scene in the field of view,
• a two dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, and each of said light sensitive detectors converting the reflected portion of said first coded sequence of light pulses into a first coded sequence of electrical pulses,
• a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors,
• a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to said clock circuit and another input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical pulse amplifier adapted to amplify the first coded sequence of electrical pulses,
• a code sequence correlator adapted to receive electrical signals from each unit cell, and to detect and validate said first coded sequence of electrical pulses, and to reject other electrical signals,
• a range measuring circuit adapted to measure a range for each unit cell, based on the number of clock cycles between the time zero reference pulse, and the time of arrival of said first coded sequence of electrical pulses,
• said second ladar sensor having
• a semiconductor laser transmitter with a laser light output transmitting a second coded sequence of light pulses through a diffusing optic for illuminating a scene in a field of view of said second ladar sensor,
• a time zero reference circuit having a time zero reference output, said time zero reference output adapted to signal the beginning of the transmission of the second coded sequence of light pulses,
• receiving optics for collecting and conditioning the coded sequence of light pulses reflected from said scene in the field of view,
• a two dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, and each of said light sensitive detectors converting the reflected portion of said second coded sequence of light pulses into a second coded sequence of electrical pulses,
• a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors,
• a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to said clock circuit and another input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical pulse amplifier adapted to amplify the second coded sequence of electrical pulses,
• a code sequence correlator adapted to receive electrical signals from each unit cell, and to detect and validate said second coded sequence of electrical pulses, and to reject other electrical signals,
• a range measuring circuit adapted to measure a range for each unit cell, based on the number of clock cycles between the time zero reference pulse, and the time of arrival of said second coded sequence of electrical pulses.

A ladar sensor comprising:

• a semiconductor laser transmitter with a laser light output transmitting a modulated burst of light through a diffusing optic for illuminating a scene in a field of view of said ladar sensor,
• a time zero reference circuit having a time zero reference output, said time zero reference output adapted to signal the beginning of the transmission of said modulated burst of light,
• receiving optics for collecting and conditioning the modulated burst of light reflected from said scene in the field of view,
• a two dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, and each of said light sensitive detectors converting the reflected portion of said modulated burst of light into a modulated electrical burst,
• a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors,
• a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to said clock circuit and another input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical amplifier adapted to amplify the modulated electrical burst,
• voltage sampling circuit connected to the output of each of said electrical amplifiers, and adapted to produce a set of analog samples of said modulated electrical burst,
• an analog to digital converter connected to each of said voltage sampling circuits, and said analog to digital converter adapted to produce a set of digitized analog samples for each unit cell
• a digital processor with a hardware implemented floating point divide unit adapted to execute a mathematical algorithm on said digitized analog samples for each unit cell, and to thereby demodulate said modulated electrical burst from each unit cell,
• and said digital processor also adapted to measure a range for each unit cell, based on the number of clock cycles between the time zero reference output, and the time of arrival of said modulated electrical burst.