Lidar system with improved scanning speed for high-resolution depth mapping

• US 9,841,495 B2
• Filed: 11/03/2016
• Issued: 12/12/2017
• Est. Priority Date: 11/05/2015
• Status: Active Grant

• Current Assignee: Luminar Technologies, Inc.
• Original Assignee: Luminar Technologies, Inc.
• Inventors: Campbell, Scott R., Eichenholz, Jason M., Martin, Lane A., Weed, Matthew D.
• Primary Examiner(s): Abraham, Samantha K
• Application Number:
  US15/342,595
• Publication Number:
  US 20170131387A1
• Time in Patent Office: 404 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 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A lidar system may have a light source configured to emit a pulse of light and a scanner that scans a field of view of the light source in a forward-scanning direction across a plurality of pixels located downrange from the lidar system. The scanner can direct the pulse of light toward the second pixel and scan a field of view of a first detector. The first-detector field of view can be offset from the light-source field of view in a direction opposite the forward-scanning direction. When the pulse is emitted, the first-detector field of view can at least partially overlap the first pixel and the light-source field of view can at least partially overlap the second pixel. The first detector can be configured to detect a portion of the pulse of light scattered by a target located at least partially within the second pixel.

Claims

1. A lidar system comprising:

a light source configured to emit a pulse of light;

a scanner configured to;

scan a field of view of the light source in a forward-scanning direction across a plurality of pixels located downrange from the lidar system, wherein the plurality of pixels comprises a first pixel and a second pixel, wherein the second pixel is located adjacent to the first pixel along the forward-scanning direction;

direct the pulse of light toward the second pixel; and

scan a field of view of a first detector of the lidar system, wherein;

the first-detector field of view is scanned in the forward-scanning direction across the plurality of pixels; and

the first-detector field of view is offset from the light-source field of view in a direction opposite the forward-scanning direction,

wherein, when the pulse is emitted;

the first-detector field of view at least partially overlaps the first pixel; and

the light-source field of view at least partially overlaps the second pixel; and

the first detector, wherein the first detector is configured to detect a portion of the pulse of light scattered by a target located at least partially within the second pixel.

2. The lidar system of claim 1, further comprising a processor configured to determine a distance from the lidar system to the target based at least in part on a time of flight of the pulse of light.

3. The lidar system of claim 1, wherein if the distance from the lidar system to the target corresponds to a maximum range of the lidar system, then, when the first detector detects the portion of the pulse of light, the first-detector field of view overlaps substantially all of the second pixel.

4. The lidar system of claim 1, wherein if the target is a close-range target located within 20% of a maximum range of the lidar system, then, when the first detector detects the portion of the pulse of light, the first-detector field of view overlaps less than or equal to 20% of the second pixel.

5. The lidar system of claim 1, wherein if the target is a midrange target located between 20% and 80% of a maximum range of the lidar system, then, when the first detector detects the portion of the pulse of light, the first-detector field of view overlaps between 20% and 80% of the second pixel.

6. The lidar system of claim 1, wherein if the target is located a distance greater than or equal to 80% of a maximum range of the lidar system, then, when the first detector detects the portion of the pulse of light, the first-detector field of view overlaps greater than or equal to 80% of the second pixel.

7. The lidar system of claim 1, wherein an angular size of the first-detector field of view is substantially equal to an angular size of the light-source field of view.

8. The lidar system of claim 1, wherein the second pixel being located adjacent to the first pixel along the forward-scanning direction corresponds to the light-source field of view beginning to scan across the first pixel prior to scanning across the second pixel.

9. The lidar system of claim 1, wherein a time for the first detector field of view to scan a width of one pixel is approximately equal to a round-trip time for a maximum range of the lidar system.

10. The lidar system of claim 1, wherein a time for the light-source field of view to scan a width of one pixel is approximately equal to a round-trip time for a maximum range of the lidar system.

11. The lidar system of claim 1, wherein the first-detector field of view being offset from the light-source field of view in the direction opposite the forward-scanning direction is such that the first-detector field of view is aligned with the second pixel at a time after the pulse of light is emitted that corresponds to a round-trip time for a maximum range of the lidar system.

12. The lidar system of claim 1, wherein:

the first-detector field of view is aligned with the second pixel at a time after the pulse of light is emitted that corresponds to a round-trip time for a maximum range of the lidar system; and

the light source is further configured to emit another pulse of light at a time after the first-detector field of view is aligned with the second pixel.

13. The lidar system of claim 1, further comprising a second detector, wherein a field of view of the second detector is offset from the light-source field of view in the forward-scanning direction.

14. The lidar system of claim 13, wherein, when the pulse is emitted, the second-detector field of view overlaps less than or equal to 20% of the second pixel.

15. The lidar system of claim 13, wherein the scanner is further configured to:

scan the light-source field of view in a reverse-scanning direction corresponding to the direction opposite the forward-scanning direction; and

scan the second-detector field of view in the reverse-scanning direction.

16. The lidar system of claim 15, wherein:

the light source is further configured to emit an additional pulse of light while the scanner is scanning the light-source field of view and the second-detector field of view in the reverse-scanning direction; and

the second detector is configured to detect a portion of the additional pulse of light which is scattered by a target located downrange from the lidar system.

17. The lidar system of claim 15, wherein:

the forward-scanning direction corresponds approximately to a left-to-right direction; and

the reverse-scanning direction corresponds approximately to a right-to-left direction.

18. A method comprising:

emitting, by a light source of a lidar system, a pulse of light;

scanning a field of view of the light source in a forward-scanning direction across a plurality of pixels located downrange from the lidar system, wherein the plurality of pixels comprises a first pixel and a second pixel, wherein the second pixel is located adjacent to the first pixel along the forward-scanning direction;

directing the pulse of light toward the second pixel;

scanning a field of view of a first detector of the lidar system, wherein;

the first-detector field of view is scanned in the forward-scanning direction across the plurality of pixels; and

the first-detector field of view is offset from the light-source field of view in a direction opposite the forward-scanning direction, wherein, when the pulse is emitted;

the first-detector field of view at least partially overlaps the first pixel; and

the light-source field of view at least partially overlaps the second pixel; and

detecting a portion of the pulse of light scattered by a target located at least partially within the second pixel.

19. The method of claim 18, further comprising determining a distance from the lidar system to the target based at least in part on a time of flight of the pulse of light.

20. The method of claim 18, further comprising:

scanning the light-source field of view in a reverse-scanning direction corresponding to the direction opposite the forward-scanning direction;

scanning a field of view of a second detector of the lidar system in the reverse-scanning direction, wherein the second-detector field of view is offset from the light-source field of view in the forward-scanning direction.