Method and system for optimizing scanning of coherent LIDAR

1. A light detection and ranging (LIDAR) system, comprising:

a laser source that is configured to generate a laser beam;

a preliminary scanner configured to scan the laser beam as a first beam along a first path and as a second beam along a second path, the first path and the second path extend in a beam plane;

a motor;

a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis that extends in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along the first path from a first side of the rotation axis and towards the rotation axis, the first scanner configured to deflect the first beam in a first scan plane angled relative to the beam plane at a first angle through a first region for detecting objects in a first field near the LIDAR system; and

a second scanner coupled to the motor, the motor configured to rotate the second scanner in a second direction about the rotation axis different than the first direction to deflect the second beam on the second scanner, the second scanner positioned to receive the second beam along the second path from the first side of the rotation axis and towards the rotation axis, the second scanner configured to deflect the second beam in a second scan plane angled relative to the beam plane at a second angle through a second region for detecting objects in a second field far from the LIDAR system relative to the first field, the first region is below the second region relative to the rotation axis and the first region has a greater angular extent in the beam plane than the second region.

2. The LIDAR system of claim 1 , wherein the first scanner is a first polygon scanner and the second scanner is a second polygon scanner.

3. The LIDAR system of claim 1 , wherein:

the first scanner is configured to deflect the first beam from a first angle in the first scan plane to a second angle in the first scan plane less than or equal to sixty degrees from the first angle in the first scan plane, the first scan plane in a first scan region; and

the second scanner is configured to deflect the second beam from a first angle in the second scan plane to a second angle in the second scan plane less than or equal to sixty degrees from the first angle in the second scan plane, the second scan plane is in a second scan region adjacent to the first scan region in elevation.

4. The LIDAR system of claim 1 , wherein the first scanner is configured to rotate at a first rotation speed, the second scanner is configured to rotate at a second rotation speed, and the first rotation speed is greater than the second rotation speed.

5. The LIDAR system of claim 1 , further comprising at least one collimator configured to provide the first beam to the first scanner and the second beam to the second scanner.

6. The LIDAR system of claim 1 , wherein the first scanner is a polygon scanner that has an inscribed diameter greater than or equal to 1 inch and less than or equal to 3 inches, and a height greater than or equal to 2 inches and less than or equal to 3 inches.

7. An autonomous vehicle control system, comprising:

a laser source that is configured to generate a laser beam;

a motor;

a preliminary scanner configured to scan the laser beam as a first beam along a first path and as a second beam along a second path, the first path and the second path extend in a beam plane;

a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis that extends in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along the first path from a first side of the rotation axis and towards the rotation axis, the first scanner configured to deflect the first beam in a first scan plane angled relative to the beam plane at a first angle through a first region for detecting objects in a first field near the LIDAR system;

a second scanner coupled to the motor, the motor configured to rotate the second scanner in a second direction about the rotation axis different than the first direction to deflect the second beam on the second scanner, the second scanner positioned to receive the second beam along the second path from the first side of the rotation axis and towards the rotation axis, the second scanner configured to deflect the second beam in a second scan plane angled relative to the beam plane at a second angle through a second region for detecting objects in a second field far from the LIDAR system relative to the first field, the first region is below the second region relative to the rotation axis and the first region has a greater angular extent in the beam plane than the second region; and

one or more processors configured to:

receive a return signal corresponding to at least one of the first beam or the second beam; and

transmit a control signal, based on the return signal, to at least one of a steering system of an autonomous vehicle or a braking system of the autonomous vehicle to control at least one of a direction or a speed of the autonomous vehicle.

8. The autonomous vehicle control system of claim 7 , wherein the one or more processors are configured to determine at least one of a range to or a velocity of an object responsive to the return signal.

9. An autonomous vehicle, comprising:

a LIDAR system comprising:

a laser source that is configured to generate a laser beam;

a preliminary scanner configured to scan the laser beam as a first beam along a first path and as a second beam along a second path, the first path and the second path extend in a beam plane;

a motor;

a first scanner coupled to the motor, the motor configured to rotate the first scanner in a first direction about a rotation axis that extends in the beam plane to deflect the first beam on the first scanner, the first scanner positioned to receive the first beam along the first path from a first side of the rotation axis and towards the rotation axis, the first scanner configured to deflect the first beam in a first scan plane angled relative to the beam plane at a first angle through a first region for detecting objects in a first field near the LIDAR system; and

a second scanner coupled to the motor, the motor configured to rotate the second scanner in a second direction about the rotation axis different than the first direction to deflect the second beam on the second scanner, the second scanner positioned to receive the second beam along the second path from the first side of the rotation axis and towards the rotation axis, the second scanner configured to deflect the second beam in a second scan plane angled relative to the beam plane at a second angle through a second region for detecting objects in a second field far from the LIDAR system relative to the first field, the first region is below the second region relative to the rotation axis and the first region has a greater angular extent in the beam plane than the second region;

a steering system;

a braking system; and

a vehicle controller comprising one or more hardware processors configured to transmit a control signal, based on a return signal corresponding to at least one of the first beam or the second beam, to control at least one of the steering system or the braking system.

10. The autonomous vehicle of claim 9 , wherein the LIDAR system is mounted to the autonomous vehicle so that the second scanner is above the first scanner.

11. The autonomous vehicle of claim 9 , wherein the LIDAR system is mounted to at least one of a front or a top of the autonomous vehicle.

12. The autonomous vehicle of claim 9 , wherein the vehicle controller is configured to determine at least one of a range to or a velocity of an object responsive to the return signal.