Method and system for scanning ladar transmission with pulse modulation

• US 9,885,778 B2
• Filed: 08/14/2015
• Issued: 02/06/2018
• Est. Priority Date: 08/15/2014
• Status: Active Grant

• Current Assignee: AEye, Inc.
• Original Assignee: AEye, Inc.
• Inventors: Dussan, Luis Carlos
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US14/827,206
• Publication Number:
  US 20160047900A1
• Time in Patent Office: 907 Days
• Field of Search: 356 4, 356 401
• 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 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/499 using polarisation effects

Abstract

Various embodiments are disclosed for improved scanning ladar transmission, including but not limited to an example embodiment where a scanning ladar transmission system employs pulse modulation.

Claims

1. A method comprising:

controlling a scan pattern for a scanning ladar transmission system to target a plurality of range points according to the scan pattern, wherein the controlling step comprises (1) scanning a first mirror of the scanning ladar transmission system to a plurality of first mirror scan positions to target the scanning ladar transmission system along a first axis based on a first control signal, and (2) scanning a second mirror of the scanning ladar transmission system to a plurality of second mirror scan positions to target the scanning ladar transmission system along a second axis based on a second control signal, wherein the first and second axes are orthogonal to each other, and wherein the combination of the first and second mirror scan positions define where the scanning ladar transmission system is targeted; and

transmitting, by the controlled scanning ladar transmission system, a plurality of modulated ladar pulses toward the range points in accordance with the scan pattern, wherein the transmitting step comprises (1) firing a light source of the scanning ladar transmission system to transmit a modulated ladar pulse toward the scanning first mirror, whereupon the modulated ladar pulse is reflected toward the scanning second mirror, whereupon the modulated ladar pulse is reflected toward a targeted range point, and (2) repeating the firing step for a plurality of the targeted range points as the first and second mirrors continue to scan.

3. The method of claim 1 wherein the transmitting step further comprises transmitting the modulated ladar pulses such that a plurality of the modulated ladar pulses are traveling to and/or from a plurality of the targeted range points at the same time.

4. The method of claim 3 wherein the scanning ladar transmission system comprises a first light source and a second light source, each light source configured to generate the modulated ladar pulses, the method further comprising providing a plurality of firing commands to the first and second light sources to cause the transmitting.

5. The method of claim 1 wherein the transmitting step employs pulse position modulation of the ladar pulses.

6. The method of claim 1 wherein the transmitting step employs intensity modulation of the ladar pulses.

7. The method of claim 1 wherein the transmitting step employs short asymmetric amplitude modulation (AM) ladar pulse bursts.

8. The method of claim 1 wherein the transmitting step employs polarization modulation of the ladar pulses.

9. The method of claim 1 wherein the transmitting step employs phase modulation of the ladar pulses with coherent combining.

10. The method of claim 1 wherein the scan pattern comprises a dynamic scan pattern based on an ordered set of range points.

20. The method of claim 1 further comprising a processor (1) applying a range point down selection algorithm to data representative of a field of view for the scanning ladar transmission system, and (2) selecting a subset of range points within the field of view for targeting by the scanning ladar transmission system based on the applied range point down selection algorithm, wherein the selected subset of range points serve as the range points targeted by the transmitting step.

2. An apparatus comprising:

a scanning ladar transmission system configured to control a scan pattern for the scanning ladar transmission system and target a plurality of range points according to the scan pattern, the scanning ladar transmission system comprising (1) a first mirror, (2) a second mirror, and (3) a light source;

wherein the light source is configured to generate a plurality of ladar pulses; and

wherein the scanning ladar transmission system is further configured to (1) scan the first mirror to a plurality of first mirror scan positions to target the scanning ladar transmission system along a first axis based on a first control signal, (2) scan the second mirror to a plurality of second mirror scan positions to target the scanning ladar transmission system along a second axis based on a second control signal, wherein the first and second axes are orthogonal to each other, and wherein the combination of the first and second mirror scan positions define where the scanning ladar transmission system is targeted, (3) fire the light source to transmit a modulated ladar pulse toward the scanning first mirror, whereupon the modulated ladar pulse is reflected toward the scanning second mirror, whereupon the modulated ladar pulse is reflected toward a targeted range point, and (4) repeat the fire operation for a plurality of the targeted range points as the first and second mirrors continue to scan to thereby transmit a plurality of the modulated ladar pulses toward the range points in accordance with the scan pattern.

11. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to transmit the modulated ladar pulses such that a plurality of the modulated ladar pulses are traveling to and/or from a plurality of the targeted range points at the same time.

12. The apparatus of claim 11 wherein the scanning ladar transmission system further comprises a first light source and a second light source, each light source configured to generate the modulated ladar pulses, the wherein the scanning ladar transmission system is further configured to provide a plurality of firing commands to the first and second light sources to cause the transmissions of the modulated ladar pulses.

13. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to apply pulse position modulation to the ladar pulses.

14. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to apply intensity modulation to the ladar pulses.

15. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to apply short asymmetric amplitude modulation (AM) bursts to the ladar pulses.

16. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to apply polarization modulation to the ladar pulses.

17. The apparatus of claim 2 wherein the scanning ladar transmission system is further configured to apply phase modulation to the ladar pulses with coherent combining.

18. The apparatus of claim 2 wherein the scan pattern comprises a dynamic scan pattern based on an ordered set of range points.

19. The apparatus of claim 2 wherein the scanning ladar transmission system further comprises a processor, the processor configured to (1) apply a range point down selection algorithm to data representative of a field of view for the scanning ladar transmission system, and (2) select a subset of range points within the field of view for targeting by the scanning ladar transmission system based on the applied range point down selection algorithm, wherein the selected subset of range points serve as the targeted range points.