Beam Scanning Methods for Improved Eye Safety in LiDAR Systems

• US 20200136340A1
• Filed: 10/25/2019
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Application

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Moebius, Michael G., Spector, Steven J., Byrnes, Steven J., Bessette, Christopher, Lennox, Scott Evan, Sinclair, Matthew A., Rogomentich, Francis J.
• Application Number:
  US16/663,814
• Publication Number:
  US 20200136340A1
• Time in Patent Office: Days
• CPC Class Codes: G01S 13/865 Combination of radar systems with lidar systems
• CPC Class Codes: G01S 13/867 Combination of radar systems with cameras
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/26 wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/93 for anti-collision purposes
• CPC Class Codes: G01S 7/499 using polarisation effects
• CPC Class Codes: G02B 6/3534 the optical element being diffractive, i.e. a grating
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3598 Switching means directly located between an optoelectronic element and waveguides, including direct displacement of either the element or the waveguide, e.g. optical pulse generation based on changing the optical properties of the medium G02F1/00; optical pulse generation in optical transmitters H04B10/508; optical pulse generation by controlling laser operation H01S3/00
• CPC Class Codes: H01S 3/1305 Feedback control systems

Abstract

A LiDAR system includes an array of optical emitters, an objective lens optically coupling each optical emitter to a respective unique portion of a field of view, an optical switching network coupled between a laser and the array of optical emitters and a controller coupled to the optical switching network and configured to cause the optical switching network to route light from the laser to a sequence of the optical emitters according to a dynamically varying temporal pattern and to vary the temporal pattern in a way that reduces risk of eye injury from the laser light.

Claims

1. A LiDAR system having a field of view, the LiDAR system comprising:

a laser;

an array of optical emitters;

an objective lens optically coupling each optical emitter of the array of optical emitters to a respective unique portion of the field of view;

an optical switching network coupled between the laser and the array of optical emitters;

a controller coupled to the optical switching network and configured to cause the optical switching network to route light from the laser to a sequence of optical emitters of the array of optical emitters according to a dynamically varying temporal pattern; and

an optical receiver coupled to the optical switching network and configured to receive light reflected from the field of view.

2. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern so as to vary a repetition rate at which the light from the laser illuminates a given pixel of the field of view.

3. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern so as to vary pulse width of the light from the laser for a given pixel of the field of view.

4. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern so as to vary dwell time of the light from the laser for a given pixel of the field of view.

5. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern so as to vary a revisit rate at which the light from the laser illuminates a given pixel of the field of view.

6. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern so as to vary dwell time and revisit rate of the light from the laser for a given pixel of the field of view, such that the dwell time and revisit rate are varied in inverse proportions to maintain constant reliability and accuracy.

7. A LiDAR system according to claim 6, wherein the controller is further configured to analyze consecutive return pulses of the light reflected from the field of view together.

8. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary amplitude of the light from the laser.

9. A LiDAR system according to claim 1, wherein the controller is configured to automatically dynamically vary the temporal pattern for a portion of the field of view designated as potentially including an eye of a living being.

10. A LiDAR system according to claim 9, wherein the controller is further configured to automatically detect a portion of the field of view that includes a living being and designate the portion of the field of view as potentially including an eye of a living being.

11. A LiDAR system according to claim 10, further comprising a digital camera, wherein the controller is configured to automatically analyze image date from the digital camera to automatically detect the portion of the field of view that includes the living being.

12. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned horizontally non-sequentially.

13. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned vertically non-sequentially.

14. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned horizontally non-sequentially and vertically non-sequentially.

15. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned such that a maximum of three horizontally adjacent pixels are illuminated in sequence and a maximum of three vertically adjacent pixels are illuminated in sequence.

16. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned according to a non-raster pattern.

17. A LiDAR system according to claim 1, wherein the controller is configured to cause the optical switching network to route the light from the laser to the sequence of optical emitters of the array of optical emitters such that the field of view is scanned according to a pseudorandom pattern.

18. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern at least in part according to a speed of translation of the LiDAR system.

19. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern at least in part according to an expected density of human beings in the field of view.

20. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern at least in part according to a degree of reliability of range information is needed.

21. A LiDAR system according to claim 1, wherein the controller is configured to dynamically vary the temporal pattern differently for respective different non-overlapping regions of the field of view.

22. A LiDAR system according to claim 21, wherein the controller is configured to dynamically vary the temporal pattern differently for the respective different non-overlapping regions of the field of view based at least in part on whether the respective regions are designated as potentially including an eye of a living being.