Compact economical lidar system

Abstract

A lidar pulse is time resolved in ways that avoid costly, fragile, bulky, high-voltage vacuum devices—and also costly, awkward optical remappers or pushbroom layouts—to provide preferably 3D volumetric imaging from a single pulse, or full-3D volumetric movies. Delay lines or programmed circuits generate time-resolution sweep signals, ideally digital. Preferably, discrete 2D photodiode and transimpedance-amplifier arrays replace a continuous 1D streak-tube cathode. For each pixel a memory-element array forms range bins. An intermediate optical buffer with low, well-controlled capacitance avoids corruption of input signal by these memories.

1 . A lidar system comprising:
 means for generating a measurement signal that is at least one-dimensional, corresponding to a received at-least-one-dimensional lidar-beam pulse;   said generating means comprising a detector, receiving said lidar-beam pulse and in response emitting the measurement signal, said detector having at least one transverse dimension on the order of 100 microns or smaller;   means for time-resolving the measurement signal, said resolving means comprising:
 multiple memory elements for receiving and holding successive portions of the measurement signal respectively, 
 digital means for forming a digital sweep signal defining multiple digital states corresponding to the respective memory elements, and 
 means for applying the digital sweep signal to control distribution of the successive measurement-signal portions into the respective memory elements; and 
   means for reading the measurement-signal portions from the memory elements.   
     
     
         2 . The system of  claim 1 , wherein:
 the forming means comprise a logic circuit generating a series of digital pointers addressing the memory elements respectively; and   said at least one transverse dimension of the detector is on the order of 30 to 40 microns.   
     
     
         3 . The system of  claim 2 , wherein:
 the memory elements comprise a dynamic RAM or other capacitive array receiving the measurement signal-portions substantially directly from the distribution controlled by the digital pointers.   
     
     
         4 - 17 . (canceled) 
     
     
         18 . The system of  claim 1 , for detecting and ranging objects; said system further comprising:
 means for projecting an at-least-one-dimensional light pulse toward such objects; and   means for receiving an at-least-one-dimensional reflected light pulse from such objects;   wherein the generating means comprise means for generating said measurement signal in response to the received light pulse; and   wherein said at least one transverse dimension of the detector is on the order of 30 to 40 microns.   
     
     
         19 - 33 . (canceled) 
     
     
         34 . A lidar system comprising:
 means for generating an at-least-one-dimensional measurement signal corresponding to an at-least-one-dimensional received lidar-beam pulse;   said generating means comprising a detector receiving said lidar-beam pulse and in response emitting the measurement signal, said detector having at least one transverse dimension on the order of 100 microns or smaller;   means for time-resolving the measurement signal;   multiple memory elements, comprising a dynamic RAM or other capacitive array, respectively receiving and holding time-resolved measurement-signal portions substantially directly from the resolving means; and   means for reading the held measurement-signal portions from the memory elements.   
     
     
         35 - 36 . (canceled) 
     
     
         37 . A lidar system comprising:
 means for generating a measurement signal corresponding to a received lidar-beam pulse;   a delay line that accepts successive portions of the measurement signal;   means, within the delay line, for advancing successively accepted signal portions farther into the delay line; and   means for reading multiple measurement-signal portions substantially simultaneously from multiple positions along the delay line.   
     
     
         38 - 46 . (canceled) 
     
     
         47 . A method for making three-dimensional images of a volume and features therein, using a two-dimensional array of multiple discrete photosensitive detectors and electronic circuitry connected with said detectors; said method comprising the steps of:
 directing a two-dimensional lidar pulse, reflected from the volume and features, to the array of multiple discrete photosensitive detectors;   generation of a corresponding two-dimensional array of multiple discrete electronic signals by the detectors;   passing the entire resulting array of signals from the photosensitive detectors to the electronic circuitry; and   operating the electronic circuitry to time-resolve the entire array of signals, generating a three-dimensional electronic image of the features.   
     
     
         48 - 51 . (canceled) 
     
     
         52 . A system for forming a three-dimensional image of a volume and features therein; said system comprising:
 a two-dimensional array of multiple discrete photodetectors receiving a two-dimensional lidar pulse reflected from such volume and features, and in response generating a two-dimensional array of corresponding discrete electronic signals; and   a two-dimensional array of multiple discrete electronic circuits connected to receive the array of signals from the detector array;   wherein the circuits comprise means for time-resolving the entire array of signals, to generate from said pulse a three-dimensional electronic image of the features.   
     
     
         53 - 65 . (canceled) 
     
     
         66 . The system of  claim 34 , for detecting and ranging objects; said system further comprising:
 means for projecting an at-least-one-dimensional light pulse toward such objects; and   means for receiving an at-least-one-dimensional reflected light pulse from such objects;   wherein the generating means comprise means for generating said measurement signal in response to the received light pulse; and   wherein said at least one transverse dimension of the detector is on the order of 30 to 40 microns.   
     
     
         67 . The system of  claim 2 , wherein:
 the memory elements comprise a series of discrete individual electronic memory modules, through which the measurement signal passes in succession.