Patent ID: 9453914
Filing Date: 2016-09-27
CPC Classification: G01S,H01L

Claim Text:
1. A terrain mapping ladar system with a field of view and a wavelength of operation comprising: a ladar sensor mounted to a ladar platform, said ladar sensor mounted within a radome which is attached to said ladar platform, said radome with at least one transparent surface capable of transmitting light at said wavelength of operation, wherein said ladar sensor includes: a pulsed laser light output and diffusing optic for illuminating a scene in the field of view of said ladar sensor; a time zero reference electrical output indicating a start time of pulsed laser light produced by the pulsed laser light output; a lens assembly which collects light pulse signals reflected from said scene in the field of view and directs said collected light pulse signals onto a focal plane array; said focal plane array comprising a two dimensional array of light sensitive detectors positioned in a focal plane of the lens assembly, each light sensitive detector having an output adapted to produce an electrical pulse from a reflected portion of the pulsed laser light output; a detector bias circuit connected to at least one voltage distribution grid of said focal plane array; a readout integrated circuit comprising a plurality of unit cell electrical circuits, and said focal plane array electrically and mechanically connected to the readout integrated circuit; and wherein each unit cell electrical circuit has an input amplifier electrically connected to an output of a light sensitive detector of said focal plane array, said unit cell electrical circuit adapted to amplify said electrical pulse and having a trigger circuit adapted to detect the presence of said electrical pulse and thereupon to produce an acquisition termination signal, wherein each unit cell electrical circuit further includes a unit cell timing circuit initiated by said time zero reference electrical output, said unit cell timing circuit being terminated by said acquisition termination signal, thereby measuring the time of flight of a reflected light pulse to the unit cell, said unit cell timing circuit having a unit cell time of flight output connected to an output of a readout circuit, and the readout circuit having a 3D image output comprising a plurality of the unit cell time of flight outputs, said amplifier further having an output connected to a number of sampling gates, and each sampling gate having an output connected to a storage capacitor, and each sampling gate having a control input adapted to drive the sampling gate from a high impedance state to a low impedance state, and a logic circuit having clock input and a digital counter, and having a plurality of logic outputs, and each sampling gate control input connected to a logic output, the digital counter initiated by the time zero reference electrical output, and the digital counter being terminated by an acquisition termination signal, thereby creating a plurality of analog samples of the amplifier output over a period of time, the analog samples being stored on the storage capacitors, and thereby creating a time history of analog samples of a light pulse signal reflected from the scene in the field of view said storage capacitors connected to an output circuit when selected by an output control of the readout circuit.