Lidar system

• US 9,874,635 B1
• Filed: 03/27/2017
• Issued: 01/23/2018
• Est. Priority Date: 11/30/2015
• Status: Active Grant

• Current Assignee: Luminar Technologies, Inc.
• Original Assignee: Luminar Technologies, Inc.
• Inventors: Eichenholz, Jason M., Russell, Austin K., Campbell, Scott R., Villeneuve, Alain, Cleye, Rodger W., LaChapelle, Joseph G., Weed, Matthew D., Martin, Lane A.
• Primary Examiner(s): Ratcliffe, Luke D
• Application Number:
  US15/470,718
• Time in Patent Office: 302 Days
• CPC Class Codes: G01S 17/00 Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
• CPC Class Codes: G01S 17/02 Systems using the reflection of electromagnetic waves other than radio waves G01S17/66 takes precedence
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• 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 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• 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 17/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4804 Auxiliary means for detecting or identifying lidar signals or the like, e.g. laser illuminators
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/483 Details of pulse systems
• 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 7/4863 : Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4865 : Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/4873 : by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/4876 : by removing unwanted signals G01S7/495 takes precedence
• CPC Class Codes: H01S 2301/02 : ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 3/0007 : Applications not otherwise provided for working metals or other materials by laser beam B23K26/00; using photons to produce a reactive propulsive thrust F03H3/00; optical recording of measured values in general G01D15/14; optics in general G02B; holographic processes or apparatus G03H; optical marking or sensing of data record carriers G06K7/10 - G06K7/14, G06K15/12; injection heating of plasma by laser H05H1/22; acceleration of neutral particles by electromagnetic wave pressure H05H3/04
• CPC Class Codes: H01S 3/0078 : Frequency filtering
• CPC Class Codes: H01S 3/0085 : Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/06733 : Fibre having more than one cladding
• CPC Class Codes: H01S 3/0675 : Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/06754 : Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06758 : Tandem amplifiers
• CPC Class Codes: H01S 3/08086 : Multiple-wavelength emission
• CPC Class Codes: H01S 3/094003 : the pumped medium being a fibre
• CPC Class Codes: H01S 3/094042 : of a fibre laser
• CPC Class Codes: H01S 3/094076 : Pulsed or modulated pumping H01S3/1024 takes precedence
• CPC Class Codes: H01S 3/0941 : of a laser diode
• CPC Class Codes: H01S 3/10023 : by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/1106 : Mode locking
• CPC Class Codes: H01S 3/1608 : erbium
• CPC Class Codes: H01S 3/2383 : Parallel arrangements
• CPC Class Codes: H01S 5/0057 : for temporal shaping, e.g. pulse compression, frequency chirping
• CPC Class Codes: H01S 5/0085 : for modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 5/4012 : Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4087 : emitting more than one wavelength

Abstract

A lidar system having a light source to emit an output beam and an overlap mirror having a reflecting surface with an aperture through which the output beam passes. The lidar system may include mirrors driven by a galvanometer scanner, a resonant scanner, a microelectromechanical systems device, or a voice coil motor. The mirrors may direct the output beam toward a light source field of view (FOV) and may move the light source FOV to different locations within a field of regard. The mirrors may receive reflected portions of the output beam as an input beam and direct the input beam toward the reflecting surface of the overlap mirror. The lidar system may include a receiver to receive the input beam from the reflecting surface of the overlap mirror. The receiver may have a receiver FOV that moves synchronously with, and at least partially overlaps, the light source FOV.

Claims

1. A lidar system comprising:

a light source configured to emit pulses of light as an output beam;

an overlap mirror comprising a reflecting surface with an aperture through which the output beam passes;

a scanner comprising one or more mirrors driven by a galvanometer scanner, a resonant scanner, a microelectromechanical systems (MEMS) device, or a voice coil motor, the one or more mirrors being configured to direct the output beam toward a light source field of view within a field of regard and to move the light source field of view to different locations within the field of regard, the one or more mirrors being further configured to receive reflected or scattered portions of the output beam as an input beam and to direct the input beam toward the reflecting surface of the overlap mirror; and

a receiver configured to receive the input beam from the reflecting surface of the overlap mirror, the receiver having a receiver field of view that moves synchronously with, and at least partially overlaps, the light source field of view, wherein

the light source field of view and the receiver field of view are scanned along a scanning direction; and

the receiver field of view is offset from the light source field of view in a direction opposite the scanning direction.

2. The lidar system of claim 1, further comprising a sensor head located remotely from the light source, wherein:

the sensor head comprises the scanner and the receiver; and

the sensor head is coupled to the light source by an optical link.

3. The lidar system of claim 2, wherein:

the lidar system further comprises one or more additional sensor heads;

each of the additional sensor heads comprises a respective scanner and receiver; and

the light source is coupled to each of the additional sensor heads by a respective optical link.

4. The lidar system of claim 3, wherein the lidar system is incorporated into a vehicle, and wherein the sensor head and the one or more additional sensor heads of the lidar system are positioned about the vehicle to provide at least a 180-degree view of an environment around the vehicle.

5. The lidar system of claim 1, wherein the lidar system has a maximum range of at least 50 meters.

6. The lidar system of claim 1, wherein the field of regard comprises:

a horizontal field of regard of at least 25 degrees; and

a vertical field of regard of at least 5 degrees.

7. The lidar system of claim 1, wherein the lidar system has a horizontal resolution of at least 100 pixels and a vertical resolution of at least 4 pixels.

8. The lidar system of claim 1, wherein the lidar system is configured to generate point clouds of distance measurements at a rate between approximately 0.1 frames per second and approximately 1,000 frames per second.

9. The lidar system of claim 1, wherein the scanner comprises:

a first mirror driven by a first galvanometer scanner that scans the first mirror along a first direction; and

a second mirror driven by a second galvanometer scanner that scans the second mirror along a second direction substantially orthogonal to the first direction.

10. The lidar system of claim 1, wherein the scanner comprises:

a first mirror driven by a resonant scanner that scans the first mirror along a first direction; and

a second mirror driven by a galvanometer scanner that scans the second mirror along a second direction substantially orthogonal to the first direction.

11. The lidar system of claim 1, wherein the scanner comprises two mirrors driven synchronously, wherein the synchronously driven mirrors trace out a scan pattern that comprises substantially straight lines.

12. The lidar system of claim 1, wherein the scanner comprises a mirror driven by two actuators configured to scan the mirror along two substantially orthogonal directions.

13. The lidar system of claim 1, wherein the scanner comprises a mirror configured to be scanned along two axes, wherein motion along each axis is provided by two actuators arranged in a push-pull configuration.

14. The lidar system of claim 1, wherein an angular extent of the light source field of view is approximately equal to an angular extent of the receiver field of view.

15. The lidar system of claim 1, wherein:

the light-source field of view has an angular extent of less than or equal to 50 milliradians; and

the receiver field of view has an angular extent of less than or equal to 50 milliradians.

16. The lidar system of claim 1, wherein an angular extent of the receiver field of view is approximately twice an angular extent of the light source field of view.