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

• US 9,897,687 B1
• Filed: 04/04/2017
• Issued: 02/20/2018
• 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:
  US15/479,167
• Time in Patent Office: 322 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 pulses of light along a field of view of the light source and a scanner to scan the light source field of view in a scanning direction across a plurality of pixels located downrange from the lidar system. The scanner can direct a pulse of light, which is emitted by the light source along the light source field of view, toward a pixel and can scan a field of view of a first detector. The first detector field of view can be scanned in the scanning direction across the plurality of pixels and the scanning speed of the first detector field of view can be approximately equal to the scanning speed of the light source field of view. The first detector can detect a portion of the pulse of light scattered by a target located at least partially within the pixel.

Claims

1. A lidar system comprising:

a light source configured to emit pulses of light along a field of view of the light source;

a scanner configured to;

scan the light-source field of view in a scanning direction across a plurality of pixels located downrange from the lidar system;

direct a pulse of light, which is emitted by the light source along the light-source field of view, toward a pixel of the plurality of pixels; 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 scanning direction across the plurality of pixels; and

a scanning speed of the first-detector field of view is approximately equal to a scanning speed of the light-source field of view; 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 pixel.

2. The lidar system of claim 1, wherein the first-detector field of view at least partially overlaps the light-source field of view while the first-detector field of view and the light-source field of view are scanned.

3. The lidar system of claim 1, wherein the light-source field of view is contained within the first-detector field of view while the light-source field of view and the first-detector field of view are scanned.

4. The lidar system of claim 1, wherein the first-detector field of view is centered on the light-source field of view while the light-source field of view and the first-detector field of view are scanned.

5. The lidar system of claim 1, wherein, when the portion of the scattered pulse of light is detected by the first detector, the first-detector field of view at least partially overlaps the pixel.

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

7. The lidar system of claim 1, wherein, when the pulse of light is emitted, the light-source field of view overlaps substantially all of the pixel.

8. The lidar system of claim 1, wherein, when the pulse of light is emitted, the first-detector field of view at least partially overlaps another pixel of the plurality of pixels, wherein the another pixel is located adjacent to the pixel along the scanning direction.

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

10. The lidar system of claim 1, wherein the first-detector field of view is larger than the light-source field of view.

11. The lidar system of claim 1, wherein an angular size of the first-detector field of view is three to four times larger than an angular size of the light-source field of view.

12. The lidar system of claim 1, wherein the first-detector field of view is offset from the light-source field of view in a direction opposite the scanning direction so that the first-detector field of view lags behind the light-source field of view while the first-detector field of view and the light-source field of view are scanned in the scanning direction.

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

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

15. The lidar system of claim 1, wherein the first detector comprises an avalanche photodiode (APD).

16. 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.

17. The lidar system of claim 1, further comprising a second detector, wherein:

the scanning direction corresponds to a first scanning direction;

the first-detector field of view is offset from the light-source field of view in a direction opposite the first scanning direction so that the first-detector field of view lags behind the light-source field of view when scanning in the first scanning direction; and

a field of view of the second detector is offset from the light-source field of view in the first scanning direction so that the second-detector field of view leads the light-source field of view when scanning in the first scanning direction.

18. The lidar system of claim 17, wherein the scanner is further configured to:

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

scan the second-detector field of view in the second scanning direction, wherein the second-detector field of view is offset from the light-source field of view so that the second-detector field of view lags the light-source field of view when scanning in the second scanning direction.

19. The lidar system of claim 18, 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 second scanning direction; and

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

20. The lidar system of claim 18, wherein:

the first scanning direction corresponds to a left-to-right direction from the perspective of the scanner; and

the second scanning direction corresponds to a right-to-left direction from the perspective of the scanner.