HYBRID FLASH LIDAR SYSTEM

• US 20170343653A1
• Filed: 05/27/2016
• Published: 11/30/2017
• Est. Priority Date: 05/27/2016
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Weinberg, Harvey
• Granted Patent: US 10,429,496 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

Improved flash light detection and ranging (also referred to herein as “flash LIDAR”) systems and methods for determining the distance to a target object disposed in a field-of-view. A flash LIDAR system can include an array of illuminators, an array of light detectors, and a signal processor/controller, as well as have a field-of-view in which a target object may be disposed. The flash LIDAR system can effectively divide the field-of-view into a plurality of segments, and each illuminator in the illuminator array can be made to correspond to a specific segment of the field-of-view. The flash LIDAR system can also effectively divide the light detector array into a plurality of subsets of light detectors. Like the respective illuminators in the illuminator array, each subset of light detectors in the light detector array can be made to correspond to a specific segment of the field-of-view.

Claims

1. A flash LIDAR system having a field-of-view configured to encompass at least a portion of a target object, the system comprising:

a flash illuminator array including a plurality of illuminators;

a flash detector array including a plurality of light detectors, the flash detector array being divided into a plurality of subsets of light detectors; and

a signal processor/controller,

wherein the field-of-view is divided into a plurality of segments,

wherein the plurality of illuminators are operative to illuminate corresponding segments, respectively, of the field-of-view, the plurality of illuminators being further operative to transmit, in turn, one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view,

wherein the plurality of subsets of light detectors are operative, in response to the one or more light beam pulses transmitted, in turn, by the respective illuminators, to receive one or more reflected light beam pulses from the plurality of segments, respectively, of the field-of-view, and

wherein the signal processor/controller is operative to determine an elapsed time between transmission of the one or more light beam pulses by the respective illuminators and reception of the one or more reflected light beam pulses at the respective subsets of light detectors in order to obtain a range to the target object.

2. The system of claim 1 further comprising:

a plurality of controllable media or devices having controllable refraction angles,

wherein each of at least some of the plurality of illuminators is operative to transmit the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view through a respective one of the plurality of controllable media or devices.

3. The system of claim 2 wherein the signal processor/controller is further operative to control the refraction angle of each controllable medium or device to direct the one or more light beam pulses transmitted by the plurality of illuminators toward the corresponding segments, respectively, of the field-of-view.

4. The system of claim 2 wherein the plurality of controllable media or devices include at least one of a lithium niobate (LiNbO₃) crystal medium and a liquid crystal waveguide device.

5. The system of claim 1 wherein the plurality of illuminators are operative to transmit, in turn, the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view in a predetermined sequence of segments.

6. The system of claim 1 wherein the plurality of illuminators are operative to transmit, in turn, the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view in a random order of segments.

7. The system of claim 1 wherein the signal processor/controller is further operative to control transmission of the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view by inserting a random time delay between one or more successive transmissions of the one or more light beam pulses.

8. The system of claim 1 wherein each of the plurality of subsets of light detectors includes a predetermined number of light detectors, and wherein the system further includes a quantity of multiplexor/trans-impedance amplifier pairs equal to the predetermined number of light detectors in each subset.

9. The system of claim 8 wherein corresponding light detectors across the plurality of subsets of light detectors are coupled to current inputs of the respective multiplexor/trans-impedance amplifier pairs.

10. The system of claim 9 wherein the signal processor/controller is further operative to provide first control signals to the respective multiplexor/trans-impedance amplifier pairs to select the corresponding light detectors at the current inputs of the plurality of multiplexor/trans-impedance amplifier pairs.

11. The system of claim 10 wherein the signal processor/controller is further operative to provide second control signals to the respective multiplexor/trans-impedance amplifier pairs to control amplifier gains provided by the respective multiplexor/trans-impedance amplifier pairs.

12. The system of claim 11 wherein the signal processor/controller is coupled to voltage outputs of the respective multiplexor/trans-impedance amplifier pairs, the signal processor/controller being further operative to determine the elapsed time between the transmission of the one or more light beam pulses by the respective illuminators and the reception of the one or more reflected light beam pulses at the respective subsets of light detectors based on voltages provided at the respective voltage outputs of the multiplexor/trans-impedance amplifier pairs.

13. A method of operating a flash LIDAR system having a field-of-view configured to encompass at least a portion of a target object, the method comprising:

providing the flash LIDAR system including a flash illuminator array having a plurality of illuminators, a flash detector array having a plurality of light detectors, and a signal processor/controller, the flash detector array being divided into a plurality of subsets of light detectors, the field-of-view being divided into a plurality of segments;

illuminating, by the plurality of illuminators, corresponding segments, respectively, of the field-of-view by transmitting, in turn, one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view;

in response to the one or more light beam pulses transmitted, in turn, by the respective illuminators, receiving, by the plurality of subsets of light detectors, one or more reflected light beam pulses from the plurality of segments, respectively, of the field-of-view; and

determining, by the signal processor/controller, an elapsed time between transmission of the one or more light beam pulses by the respective illuminators and reception of the one or more reflected light beam pulses at the respective subsets of light detectors in order to obtain a range to the target object.

14. The method of claim 13 wherein the transmitting of the one or more light beam pulses includes transmitting, in turn, the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view in a predetermined sequence of segments.

15. The method of claim 13 wherein the transmitting of the one or more light beam pulses includes transmitting, in turn, the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view in a random order of segments.

16. The method of claim 13 further comprising:

controlling, by the signal processor/controller, transmission of the one or more light beam pulses toward the corresponding segments, respectively, of the field-of-view by inserting a random time delay between one or more successive transmissions of the one or more light beam pulses.

17. A method of calibrating a flash LIDAR system, the method comprising:

providing the flash LIDAR system including a flash illuminator array having a plurality of illuminators, a flash detector array having a plurality of light detectors, and a signal processor/controller;

transmitting, by the plurality of illuminators, in turn, one or more light beam pulses toward a calibration reflector, the calibration reflector having a substantially uniform reflector surface;

in response to the one or more light beam pulses transmitted, in turn, by the respective illuminators, receiving, at the plurality of light detectors, one or more reflected light beam pulses from the calibration reflector;

measuring, by the signal processor/controller, a plurality of light intensity levels at the plurality of light detectors, respectively, of the flash detector array; and

mapping out, by the signal processor/controller, a plurality of subsets of light detectors on the flash detector array based on the measured light intensity levels, each subset of light detectors for use in receiving further reflected light beam pulses in response to further transmitted light beam pulses from a respective illuminator.

18. The method of claim 17 wherein the mapping out of the plurality of subsets of light detectors on the flash detector array includes mapping out the plurality of subsets such that each light detector in a respective subset has a measured light intensity level equal to at least a predetermined light intensity level.

19. The method of claim 17 wherein the mapping out of the plurality of subsets of light detectors on the flash detector array includes mapping out an area of at least one subset of light detectors to be less than a total area of the flash detector array in which a least one light detector has a measured light intensity level equal to at least a predetermined light intensity level.

20. The method of claim 17 wherein the mapping out of the plurality of subsets of light detectors on the flash detector array includes mapping out an area of at least one subset of light detectors to be greater than a total area of the flash detector array in which a least one light detector has a measured light intensity level equal to at least a predetermined light intensity level.