Reducing audio noise in a lidar scanner with a polygon mirror

• US 10,324,185 B2
• Filed: 04/27/2018
• Issued: 06/18/2019
• Est. Priority Date: 11/22/2017
• Status: Active Grant

• Current Assignee: Luminar Technologies, Inc.
• Original Assignee: Luminar Technologies, Inc.
• Inventors: McWhirter, John E., Campbell, Scott R.
• Primary Examiner(s): Abraham, Samantha K.
• Application Number:
  US15/965,471
• Publication Number:
  US 20190154829A1
• Time in Patent Office: 417 Days
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 26/123 Multibeam scanners, e.g. using multiple light sources or beam splitters
• CPC Class Codes: G02B 26/125 Details of the optical system between the polygonal mirror and the image plane G02B26/123, G02B26/127 take precedence; F-Theta lenses G02B13/0005
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: G02B 27/0977 Reflective elements
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/0841 comprising organic materials, e.g. polymers
• CPC Class Codes: G02B 5/09 Multifaceted or polygonal mirrors , e.g. polygonal scanning mirrors; Fresnel mirrors
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence
• CPC Class Codes: G02B 7/1821 for rotating or oscillating mirrors
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 27/14643 : Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14647 : Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
• CPC Class Codes: H01L 27/14694 : The active layers comprising only AIIIBV compounds, e.g. GaAs, InP

Abstract

An optical scanner includes a rotatable polygon mirror and a second mirror. The rotatable polygon mirrors includes a block having a first wall, a second wall, and reflective surfaces extending between the first and second walls, the reflective surfaces being angularly offset from one another along a periphery of the block; a polygon mirror axle extending into the block through at least one of the first and second walls, about which the block rotates; a motor driving rotation of the block; and chamfers in the block, each of the chamfers being bounded by a pair of adjacent reflective surfaces and the second wall. The second mirror is pivotable along an axis orthogonal to the polygon mirror axle and more proximate to the second wall of the block than the first wall of the block.

Claims

1. An optical scanner comprising:

a rotatable polygon mirror including;

a block having a first wall, a second wall, and a plurality of reflective surfaces extending between the first and second walls, the reflective surfaces being angularly offset from one another along a periphery of the block,

a polygon mirror axle extending into the block through at least one of the first and second walls, about which the block rotates,

a motor driving rotation of the block, and

a plurality of chamfered corners in the block, each of the chamfered corners being bounded by a pair of adjacent reflective surfaces and the second wall, and not bounded by the first wall; and

a second mirror pivotable along an axis orthogonal to the polygon mirror axle and more proximate to the second wall of the block than the first wall of the block.

2. The optical scanner of claim 1, wherein each of the chamfered corners is cut at an angle of 45°

to the adjacent finished reflective surfaces.

3. The optical scanner of claim 1, wherein the chamfered corners reduce a major diameter of the rotatable polygon mirror, and wherein the rotatable polygon mirror and the second mirror are positioned so that the reduced major diameter reduces a distance between the rotatable polygon mirror and the second mirror.

4. The optical scanner of claim 1, wherein each reflective surface of the block is joined to adjacent reflective surfaces of the block along a drag-reducing, non-sharp edge.

5. The optical scanner of claim 4, further comprising a housing enclosing one or more of a light source, the optical scanner, a receiver, and a controller, wherein the rotation of the polygon mirror imparts a flow of air through the housing to provide cooling to components enclosed within the housing.

6. The optical scanner of claim 1, wherein the motor imparts rotation to the polygon mirror axle.

7. The optical scanner of claim 6, wherein the motor is disposed at least partially within the block.

8. The optical scanner of claim 1, wherein the second mirror includes a block having a reflective surface facing the polygon mirror, the center of gravity of the block being displaced toward the reflective surface.

9. The optical scanner of claim 8, wherein the block of the second mirror includes a layer with a honeycomb structure.

10. The optical scanner of claim 1, wherein the block is formed of at least one of a glass substrate, a plastic, a polycarbonate, a metal, carbon fiber, or a ceramic.

11. A lidar system comprising:

a light source configured to emit light;

a receiver configured to detect the light scattered by one or more remote targets; and

an optical scanner including;

a rotatable polygon mirror comprising;

a block having a first wall, a second wall, and a plurality of reflective surfaces extending between the first and second walls, the reflective surfaces being angularly offset from one another along a periphery of the block,

a polygon mirror axle extending into the block through at least one of the first and second walls, about which the block rotates,

a motor driving rotation of the block, and

a plurality of chamfered corners in the block, each of the chamfered corners being bounded by a pair of adjacent reflective surfaces and the second wall, and not bounded by the first wall, the optical scanner further including;

a second mirror pivotable along an axis orthogonal to the polygon mirror axle and more proximate to the second wall of the block than the first wall of the block.

12. The lidar system of claim 11, wherein each of the chamfered corners is cut at an angle of 45°

to the adjacent finished reflective surfaces.

13. The lidar system of claim 11, wherein the chamfered corners reduce a major diameter of the rotatable polygon mirror, and wherein the rotatable polygon mirror and the second mirror are positioned so that the reduced major diameter reduces a distance between the rotatable polygon mirror and the second mirror.

14. The lidar system of claim 11, wherein each reflective surface of the block is joined to adjacent reflective surfaces of the block along a drag-reducing, non-sharp edge.

15. The lidar system of claim 14, the optical scanner further comprising a housing enclosing one or more of a light source, the optical scanner, a receiver, and a controller, wherein the rotation of the polygon mirror imparts a flow of air through the housing to provide cooling to components enclosed within the housing.

16. The lidar system of claim 11, wherein the motor imparts rotation to the polygon mirror axle.

17. The lidar system of claim 16, wherein the motor is disposed at least partially within the block.

18. The lidar system of claim 11, wherein the second mirror includes a block having a reflective surface facing the polygon mirror, the center of gravity of the block being displaced toward the reflective surface.

19. The lidar system of claim 18, wherein the block of the second mirror includes a layer with a honeycomb structure.

20. The lidar system of claim 11, wherein the block is formed of at least one of a glass substrate, a plastic, a polycarbonate, a metal, carbon fiber, or a ceramic.