Scanning lidar system and method

• US 10,613,200 B2
• Filed: 02/13/2018
• Issued: 04/07/2020
• Est. Priority Date: 09/19/2017
• Status: Active Grant

• Current Assignee: Veoneer, Inc. (SSW Partners LP)
• Original Assignee: Veoneer, Inc. (SSW Partners LP)
• Inventors: Hallstig, Emil, Wihlbeck, Jonas, Hansson, Peter, de Mersseman, Bernard, Puglia, Kenneth
• Primary Examiner(s): Bolda, Eric L
• Application Number:
  US15/895,460
• Publication Number:
  US 20190086518A1
• Time in Patent Office: 784 Days
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• 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 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4876 by removing unwanted signals G01S7/495 takes precedence
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/493 Extracting wanted echo signals

Abstract

A LiDAR detection system includes optical sources generating a plurality of output optical signals disposed along a first direction. A modulation circuit applies an output signal from a signal generator to the optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency-modulated modulation envelopes. A scanning device scans the output optical signals into a region over a second direction. A receiver comprising a two-dimensional array of optical detectors receives return optical signals and generates receive signals indicative of the return optical signals. The return optical signals impinge on a mask between the region and the array, the mask comprising a plurality of apertures aligned with a first dimension of the array. The receive signals are generated for a set of detectors in the array disposed along the first dimension of the array and aligned with the mask apertures.

Claims

1. A LiDAR detection system, comprising:

a plurality of optical sources disposed along a first direction for generating a plurality of output optical signals disposed along the first direction;

a signal generator for generating an output signal having a variable frequency;

a modulation circuit for receiving the output signal from the signal generator and applying the output signal from the signal generator to the plurality of optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency-modulated modulation envelopes;

optical transmission elements for transmitting the envelope-modulated output optical signals into a region;

a scanning device for scanning the plurality of envelope-modulated output optical signals over a second direction different than the first direction;

a receiver for receiving return optical signals at least partially generated by reflection of the transmitted envelope-modulated output optical signals and generating receive signals indicative of the return optical signals, the receiver comprising a two-dimensional array of optical detectors;

a mask disposed in proximity to the array between the region and the array, the return optical signals impinging on the mask, the mask comprising a plurality of apertures disposed along a direction aligned with a first dimension of the array, each aperture being adapted such that the mask blocks a first portion of the return optical signals from impinging on the array and the aperture allows a second portion of the return optical signals to impinge on the array, wherein the receive signals are generated for a set of detectors in the array disposed along the first dimension of the array and aligned with the apertures in the mask and exposed to the received return optical signals, wherein the receive signals are generated for one set of detectors at a time, the sets of detectors being offset with respect to each other along a second dimension of the array substantially orthogonal to the first dimension of the array, wherein each detector in a set of detectors comprises multiple regions, a first region of each detector receiving a return optical signal at a first time and a second region of each detector receiving another return optical signal at a second time later than the first time, wherein the first and second times occur during different sweeps of the array; and

a processor coupled to the receiver for receiving the receive signals and processing the receive signals to generate detections of one or more objects in the region.

2. The LiDAR detection system of claim 1, wherein the first portion of the return optical signals blocked by the mask are from at least one portion of the region that is not illuminated by the output optical signals.

3. The LiDAR detection system of claim 1, wherein the mask is located at or near a focal plane of a receiving lens in the receiver.

4. The LiDAR detection system of claim 1, wherein the scanning device comprises a scanning mirror for scanning the transmitted envelope-modulated output optical signals at varying angles into the region.

5. The LiDAR detection system of claim 4, wherein the scanning mirror is a micro-electromechanical (MEMS) scanning mirror.

6. The LiDAR detection system of claim 1, wherein the signal generator comprises a voltage-controlled oscillator (VCO), the frequency of the output signal being variable by a control input applied to the VCO.

7. The LiDAR detection system of claim 6, wherein the frequency of the output signal is controlled to vary according to a ramp between a first frequency and a second frequency.

8. The LiDAR detection system of claim 1, wherein the transmitted envelope-modulated output optical signals are frequency-modulated continuous-wave (FMCW) signals.

9. The LiDAR detection system of claim 1, wherein the transmitted envelope-modulated output optical signals are pulsed signals.

10. The LiDAR detection system of claim 1, wherein the optical sources comprise lasers.

11. The LiDAR detection system of claim 1, wherein the LIDAR detection system is an automotive LiDAR detection system.

12. The LiDAR detection system of claim 1, wherein the array of optical detectors comprise at least one silicon photomultiplier (SiPM) detector.

13. The LiDAR detection system of claim 1, wherein the array of optical detectors comprise at least one avalanche photodiode detector (APD).

14. The LiDAR detection system of claim 1, wherein the array of optical detectors comprise at least one multi-pixel photon counter (MPPC) detector.

15. The LiDAR detection system of claim 1, wherein the optical transmission elements comprise at least one optical element which shapes the output optical signals such that the divergence of each output optical signal is substantially reduced or minimize.

16. The LiDAR detection system of claim 1, wherein the optical transmission elements comprise lasers.

17. The LiDAR detection system of claim 1, wherein the LiDAR detection system is an automotive LiDAR detection system.

18. The LiDAR detection system of claim 1, wherein the LiDAR detection system is a biaxial system.

19. The LiDAR detection system of claim 1, wherein the LiDAR detection system is a coaxial system.