Hyper Temporal Lidar with Shot Scheduling for Variable Amplitude Scan Mirror

Patent metadata

Field	Value
Publication number	US-2022308168-A1
Application number	US-202117482820-A
Country	US
Kind code	A1
Filing date	Sep 23, 2021
Priority date	Mar 26, 2021
Publication date	Sep 29, 2022
Grant date	—

Abstract

A lidar system that includes a laser source and transmits laser pulses produced by the laser source toward range points in a field of view via a mirror that scans through a plurality of scan angles can use (1) a laser energy model to model the available energy in the laser source over time and (2) a mirror motion model to model motion of the mirror over time. The mirror can exhibit a variable scan amplitude, and a control circuit can then evaluate whether benefits such as a shorter completion time for firing laser pulse shots at a list of range points can be achieved by changing the mirror's scan amplitude. When making such decisions, the control circuit can take into account a settle time for the variable amplitude mirror that arises from changing the mirror's scan amplitude.

First claim

1 . A lidar apparatus comprising:
a laser source; a variable amplitude mirror that is scannable through a plurality of scan angles to define where the lidar apparatus is aimed along an axis within a field of view, wherein an angular extent of the scan angles for the variable amplitude mirror is defined by an amplitude for the variable amplitude mirror; and a control circuit that dynamically (1) controls a variable rate firing of laser pulse shots by the laser source toward a plurality of range points in the field of view via the variable amplitude mirror and (2) controls changes in the amplitude for the variable amplitude mirror for the laser pulse shots based on a settle time arising from amplitude changes for the variable amplitude mirror; and wherein the control circuit dynamically controls changes in the amplitude of the variable amplitude mirror by (1) determining a first completion time for a list of range points to be targeted with laser pulse shots where the variable amplitude mirror scans according to a first mirror motion model that models the scan angles for the variable amplitude mirror over time when scanning using a first amplitude for the variable amplitude mirror, (2) determining a second completion time for the list where the variable amplitude mirror scans according to a second mirror motion model that models the scan angles for the variable amplitude mirror over time when scanning using a second amplitude for the variable amplitude mirror, wherein the second completion time takes into account the settle time for the variable amplitude mirror, (3) comparing the first completion time with the second completion time, (4) controlling the variable amplitude mirror to exhibit the first amplitude with respect to firing laser pulse shots for the list if the first completion time is less than the second completion time, and (5) controlling the variable amplitude mirror to exhibit the second amplitude with respect to firing laser pulse shots for the list if the second completion time is less than the first completion time.

2 . (canceled)

3 . The apparatus of claim 1 wherein the first amplitude corresponds to a current amplitude for the variable amplitude mirror.

4 . The apparatus of claim 3 wherein the second amplitude corresponds to a smaller amplitude than the current amplitude.

5 . The apparatus of claim 1 wherein the first and second mirror motion models model the scan angles for the variable amplitude mirror as a plurality of corresponding time slots, and wherein the control circuit schedules laser pulse shots for the list by assigning the laser pulse shots to corresponding time slots defined by the first and second mirror motion models.

6 . The apparatus of claim 5 wherein the time slots reflect time intervals in a range between 5 nanoseconds and 50 nanoseconds.

7 . The apparatus of claim 1 wherein the first and second mirror motion models model the scan angles according to a cosine oscillation.

8 . The apparatus of claim 1 wherein the control circuit drives the variable amplitude mirror to scan through the scan angles along the axis in a resonant mode.

9 . The apparatus of claim 8 wherein the variable amplitude mirror comprises a first mirror, the apparatus further comprising a second mirror that is scannable through a plurality of scan angles along a second axis within the field of view, and wherein the control circuit drives the second mirror to scan in a point-to-point mode based on the range points in the field of view to be targeted with the laser pulse shots.

10 . The apparatus of claim 1 wherein the control circuit drives the scannable variable amplitude mirror to scan through the scan angles along the axis at a frequency between 100 Hz and 20 kHz.

11 . The apparatus of claim 1 wherein the control circuit drives the scannable variable amplitude mirror to scan through the scan angles along the axis at a frequency between 10 kHz and 15 kHz.

12 . The apparatus of claim 1 wherein the variable amplitude mirror comprises a MEMS mirror.

13 . The apparatus of claim 1 wherein the control circuit schedules the laser pulse shots for the list based on a laser energy model that models how much energy is available from the laser source for laser pulse shots over time.

14 . The apparatus of claim 13 wherein the laser energy model (1) models a depletion of energy in the laser source in response to each laser pulse shot, (2) models a retention of energy in the laser source after laser pulse shots, and (3) models a buildup of energy in the laser source between laser pulse shots.

15 . The apparatus of claim 13 wherein the laser source comprises an optical amplification laser source.

16 . The apparatus of claim 15 wherein the optical amplification laser source comprises a pulsed fiber laser source.

17 . The apparatus of claim 16 wherein the pulsed fiber laser source comprises a seed laser, a pump laser, and a fiber amplifier, and wherein the laser energy model models (1) seed energy for the pulsed fiber laser source over time and (2) energy stored in the fiber amplifier over time.

18 . The apparatus of claim 17 wherein the laser energy model models available energy for laser pulse shots according to a relationship of EF(t+δ)=aS(t+δ)+bEF(t), wherein a+b=1 so that a and b reflect how much energy is drained from and remains in the fiber amplifier when laser pulse shots are fired, wherein EF(t) represents laser energy for a laser pulse shot fired at time t, wherein EF(t+δ) represents laser energy for a laser pulse shot fired at time t+δ, wherein S(t+δ) represents an amount of energy deposited by the pump laser into the fiber amplifier over time duration δ, wherein t represents a fire time for a laser pulse shot, and wherein the time duration δ represents intershot spacing in time.

19 . The apparatus of claim 18 wherein S(t+δ)=δE P , wherein E P represents an amount of energy per unit of time that is deposited by the pump laser into the fiber amplifier.

20 . The apparatus of claim 15 wherein the laser energy model (1) models depletion of energy in an optical amplifier of the optical amplification laser source in response to each laser pulse shot, (2) models retention of energy in the optical amplifier after laser pulse shots, and (3) models buildup of energy in the optical amplifier between laser pulse shots.

21 . The apparatus of claim 13 wherein the laser energy model models available laser energy for laser pulse shots over time intervals in a range between 10 nanoseconds to 100 nanoseconds.

22 . The apparatus of claim 1 wherein the control circuit comprises (1) a system controller and (2) a beam scanner controller;
wherein the system controller determines an amplitude to use for the variable amplitude mirror; and
wherein the beam scanner controller (1) provides firing commands to the laser source in accordance with the list and (2) controls scanning of the variable amplitude mirror including controlling the variable amplitude mirror to exhibit the determined amplitude.

23 . A method for controlling how a plurality of targeted laser pulse shots are transmitted from a laser source into a field of view via a variable amplitude mirror that scans through a plurality of scan angles, wherein an angular extent of the scan angles for the variable amplitude mirror is defined by an amplitude for the variable amplitude mirror, the method comprising:
dynamically controlling a variable rate firing of laser pulse shots by the laser

Assignees

• Aeye Inc

Inventors

• Feru Philippe
• Dussan Luis
• Benscoter Joel
• Jung Il Woong
• Liang Alex
• Polishchuk Igor
• Steinhardt Allan

Classifications

• G01S7/4817

  relating to scanning · CPC title

• G01S17/10

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S7/4814

  of transmitters alone · CPC title