Lidar system

• US 9,857,468 B1
• Filed: 03/27/2017
• Issued: 01/02/2018
• 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:
  US15/470,708
• Publication Number:
  US 20180024241A1
• Time in Patent Office: 281 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 with a pulsed laser diode configured to produce an optical seed pulse of light at an operating wavelength between approximately 1400 nm and approximately 1600 nm. The lidar system may also include an optical amplifier configured to amplify the optical seed pulse to produce an eye-safe output optical pulse that is emitted into a field of view. The optical amplifier may produce an amount of amplified spontaneous emission (ASE) associated with the output optical pulse. The lidar system may include an optical filter configured to filter the output optical pulse to reduce the associated ASE. The lidar system may also include a receiver configured to detect at least a portion of the output optical pulse reflected or scattered from the field of view.

Claims

1. A lidar system comprising:

a pulsed laser diode configured to produce a plurality of optical seed pulses of light at an operating wavelength between approximately 1400 nm and approximately 1600 nm;

an optical amplifier configured to amplify the optical seed pulses to produce a plurality of eye-safe output optical pulses that are emitted into a field of view, the optical amplifier producing an amount of amplified spontaneous emission (ASE) associated with the output optical pulses, wherein the plurality of output optical pulses have characteristics comprising;

a pulse repetition frequency of less than or equal to 100 MHz;

a pulse duration of less than or equal to 20 nanoseconds; and

a duty cycle of less than or equal to 1%;

an optical filter configured to filter the output optical pulses to reduce the associated ASE; and

a receiver configured to detect at least a portion of the output optical pulses reflected or scattered from the field of view.

2. The lidar system of claim 1, wherein the receiver is provided in a sensor head remotely located from the pulsed laser diode, and wherein the sensor head is coupled to the pulsed laser diode or the optical amplifier by an optical link.

3. The lidar system of claim 2, wherein:

the lidar system further comprises one or more additional sensor heads, wherein the pulsed laser diode or the optical amplifier is coupled to each of the additional sensor heads by a respective optical link which conveys a respective portion of the optical seed pulses or the output optical pulses to each of the additional sensor heads.

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 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 lidar system comprises a scanner configured to scan at least a portion of the output optical pulses across 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 comprises a scanner configured to scan at least a portion of the output optical pulses with 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 pulsed laser diode comprises a distributed-feedback (DFB) laser or a distributed-Bragg reflector (DBR) laser.

9. The lidar system of claim 1, wherein the optical amplifier comprises a booster amplifier with a double-clad gain fiber having erbium dopants or erbium and ytterbium dopants.

10. The lidar system of claim 1, wherein the characteristics further comprise:

a pulse energy of at least 10 nanojoules;

a peak power of at least 1 watt; and

an average power of no more than 50 watts.

11. The lidar system of claim 1, wherein the optical filter is configured to transmit light at one or more wavelengths comprising the operating wavelength and to attenuate light away from the transmitted wavelengths by at least 10 dB.

12. A lidar system comprising:

a pulsed laser diode configured to produce a plurality of optical seed pulses of light at an operating wavelength between approximately 1400 nm and approximately 1600 nm;

an optical amplifier configured to amplify the optical seed pulses to produce a plurality of output optical pulses comprising an eye-safe output optical pulse that is emitted into a field of view, the optical amplifier producing an amount of amplified spontaneous emission (ASE) associated with the output optical pulses;

an optical filter configured to filter the output optical pulses to reduce the associated ASE;

a scanner configured to scan at least a portion of the output optical pulses; and

a receiver configured to detect at least a portion of the output optical pulses reflected or scattered from the field of view,

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.

13. The lidar system of claim 12, wherein the receiver is provided in a sensor head remotely located from the pulsed laser diode, and wherein the sensor head is coupled to the pulsed laser diode or the optical amplifier by an optical link.

14. The lidar system of claim 12, wherein the scanner is configured to scan the portion of the output optical pulses across a horizontal field of regard of at least 25 degrees and a vertical field of regard of at least 5 degrees.

15. The lidar system of claim 12, wherein the scanner is configured to scan the portion of the output optical pulses with a horizontal resolution of at least 100 pixels and a vertical resolution of at least 4 pixels.

16. A lidar system comprising:

a plurality of pulsed laser diodes, each pulsed laser diode being configured to produce optical seed pulses of light at a different operating wavelength between approximately 1400 nm and approximately 1600 nm;

an optical multiplexer configured to combine the optical seed pulses produced by each laser diode into a single optical fiber;

an optical amplifier configured to amplify the combined optical seed pulses to produce a plurality of output optical pulses comprising an eye-safe output optical pulse that is emitted into a field of view, the optical amplifier producing an amount of amplified spontaneous emission (ASE) associated with the output optical pulses;

an optical filter configured to filter the output optical pulses to reduce the associated ASE; and

a receiver configured to detect at least a portion of the output optical pulses reflected or scattered from the field of view.

17. The lidar system of claim 16, wherein the receiver is provided in a sensor head remotely located from the plurality of pulsed laser diodes, and wherein the sensor head is coupled to the pulsed laser diodes or the optical amplifier by an optical link.

18. The lidar system of claim 17, wherein the lidar system further comprises one or more additional sensor heads, wherein the optical amplifier is coupled to each of the additional sensor heads by a respective optical link which conveys a respective portion of the optical seed pulses or the output optical pulses to each of the additional sensor heads.

19. The lidar system of claim 16, further comprising a scanner configured to scan at least a portion of the output optical pulses across a horizontal field of regard of at least 25 degrees and a vertical field of regard of at least 5 degrees.

20. The lidar system of claim 16, wherein the optical amplifier comprises a booster amplifier with a double-clad gain fiber having erbium dopants or erbium and ytterbium dopants.