Method and system for ladar transmission with spinning polygon mirror for dynamic scan patterns

• US 10,073,166 B2
• Filed: 08/14/2015
• Issued: 09/11/2018
• Est. Priority Date: 08/15/2014
• Status: Active Grant

• Current Assignee: AEye, Inc.
• Original Assignee: AEye, Inc.
• Inventors: Dussan, Luis Carlos
• Primary Examiner(s): Abraham, Samantha K
• Application Number:
  US14/827,175
• Publication Number:
  US 20160047896A1
• Time in Patent Office: 1,124 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 17/86 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 the scanning ladar transmission system includes a spinning polygon mirror for targeting range points according to a dynamic scan pattern.

Claims

1. A method comprising:

processing a shot list, the shot list comprising a plurality of range points for targeting by a scanning ladar transmission system, wherein the scanning ladar transmission system comprises (1) a first mirror that is scannable with respect to a first axis, and (2) a second mirror that is scannable with respect to second axis that is orthogonal to the first axis, wherein the first mirror comprises a spinning polygon mirror;

controlling a dynamic scan pattern for the scanning ladar transmission system by scanning the spinning polygon mirror and the second mirror to a plurality of mirror scan positions based on the processed shot list to target the range points of the processed shot list, wherein the combination of the mirror scan positions for the spinning polygon mirror and the second mirror define the range points to which the scanning ladar transmission system is targeted; and

transmitting, by the controlled scanning ladar transmission system, a plurality of ladar pulses toward the range points of the processed shot list in accordance with the dynamic scan pattern.

2. The method of claim 1 wherein the second mirror comprises a microelectromechanical systems (MEMS) mirror.

3. The method of claim 2 wherein the controlling step comprises:

scanning the spinning polygon mirror in one direction in a non-resonant mode; and

scanning the MEMS mirror in a plurality of directions in a non-resonant, point-to-point mode.

4. The method of claim 3 wherein the controlling step further comprises:

scanning the spinning polygon mirror as a fast axis mirror; and

scanning the MEMS mirror as a slow axis mirror.

5. The method of claim 2 wherein the spinning polygon mirror comprises an N-sided spinning polygon mirror, and wherein the controlling step comprises spinning the spinning polygon mirror at a spin rate such that N multiplied by the spin rate exhibits a ratio in the range of 10:

1 to 18;

1 relative to a resonant frequency for the second mirror.

6. The method of claim 1 further comprising:

a light source directing a plurality of ladar pulses onto the spinning polygon mirror;

the spinning polygon mirror reflecting the ladar pulses onto the second mirror; and

the second mirror reflecting the ladar pulses for transmission toward the targeted range points, the targeted range points being defined by the combination of mirror scan positions for the spinning polygon mirror and the second mirror when the ladar pulses are incident thereon.

7. The method of claim 1 wherein the spinning polygon mirror has a polygon shape with a number of sides within a range between 3-8 sides.

8. The method of claim 1 wherein the scanning ladar transmission system further comprises a plurality of laser sources and at least one additional mirror that is positioned to receive ladar pulses reflected by the spinning polygon mirror, the method further comprising:

operating the scanning ladar transmission system as a multi-beam scanner using the plurality of laser sources.

9. The method of claim 8 wherein the plurality of laser sources provide a plurality of fields of view for the scanning ladar transmission system, the method further comprising:

tilting the fields of view using a wedge or mirror.

10. 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.

11. An apparatus comprising:

a scanning ladar transmission system configured to direct a plurality of ladar pulses toward a plurality of range points via a plurality of scanable mirrors, wherein the scanning ladar transmission system comprises;

a beam scanner, the beam scanner including a first mirror and a second mirror, wherein the first mirror comprises a spinning polygon mirror, wherein the beam scanner is configured to (1) scan the first mirror to a plurality of mirror scan positions in response to a first control signal to target the scanning ladar transmission system along a first axis, and (2) scan the second mirror to a plurality of mirror scan positions in response to a second control signal to target the scanning ladar transmission system along a second axis, and wherein the combination of the mirror scan positions for the first and second mirrors defines the range points to which the scanning ladar transmission system is targeted; and

a beam scanner controller, wherein the beam scanner controller is configured to generate the first and second control signals for use by the beam scanner such that the first and second control signals define a dynamic scan pattern for the scanning ladar transmission system with respect to the range points.

12. The apparatus of claim 11 wherein the scanning ladar transmission system further comprises:

a light source positioned and configured to direct a plurality of ladar pulses onto the spinning polygon mirror, whereupon the spinning polygon mirror is configured to reflect the ladar pulses onto the second mirror, whereupon the second mirror is configured to reflect the ladar pulses for transmission toward the targeted range points, the targeted range points being defined by the combination of mirror scan positions for the spinning polygon mirror and the second mirror when the ladar pulses are incident thereon.

13. The apparatus of claim 12 wherein the second mirror comprises a microelectromechanical systems (MEMS) mirror.

14. The apparatus of claim 13 wherein the beam scanner is further configured to (1) scan the spinning polygon mirror in one direction in a non-resonant mode in response to the first control signal, and (2) scan the MEMS mirror in a plurality of directions in a non-resonant, point-to-point mode in response to the second control signal.

15. The apparatus of claim 14 wherein the beam scanner is further configured to (1) scan the spinning polygon mirror as a fast axis mirror, and (2) scan the MEMS mirror as a slow axis mirror.

16. The apparatus of claim 15 wherein the spinning polygon mirror comprises an N-sided spinning polygon mirror, and wherein the beam scanner is further configured to spin the spinning polygon mirror at a spin rate such that N multiplied by the spin rate exhibits a ratio in the range of 10:

1 to 18;

1 relative to a resonant frequency for the MEMS mirror.

17. The apparatus of claim 12 wherein the scanning ladar transmission system further comprises a plurality N of the light sources, each light source positioned to render the scanning ladar transmission system as a multi-beam scanner.

18. The apparatus of claim 17 wherein the beam scanner further comprises an additional mirror positioned to receive ladar pulses reflected by the spinning polygon mirror.

19. The apparatus of claim 18 wherein the value of N is a member of the group consisting of 2-16, and wherein the additional mirror comprises N−

1 additional mirrors positioned to receive ladar pulses reflected by the spinning polygon mirror.

20. The apparatus of claim 17 wherein the spinning polygon mirror has a polygon shape with a number of sides within a range between 3-8 sides.

21. The apparatus of claim 17 wherein the beam scanner further comprises a wedge or mirror positioned to tilt a field of view for the multi-beam scanner.

22. The apparatus of claim 11 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.