Manufacturing a balanced polygon mirror

• US 10,663,585 B2
• Filed: 04/27/2018
• Issued: 05/26/2020
• Est. Priority Date: 11/22/2017
• Status: Active Grant

• Current Assignee: Luminar Technologies, Inc.
• Original Assignee: Luminar Technologies, Inc.
• Inventors: McWhirter, John E.
• Primary Examiner(s): Cherry, Euncha P
• Application Number:
  US15/965,519
• Publication Number:
  US 20190154889A1
• Time in Patent Office: 760 Days
• Field of Search: 3592161-2191
• 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

A technique for manufacturing highly balanced rotatable polygon mirrors for use in scanners includes forming a block having a first wall, a second wall, and reflective surfaces extending between the first and second walls, the surfaces being angularly offset from one another along a periphery of the block. The technique includes applying a coarse balancing procedure to the block, making the surfaces reflective, mating the block to a motor, and applying a precise balancing procedure to the block. The technique also includes imparting rotation to the block and removing material from the block via the first wall using high-energy laser pulses.

Claims

1. A method for manufacturing highly balanced rotatable polygon mirrors for use in scanners, the method comprising:

forming a block having a first wall, a second wall, and a plurality of surfaces extending between the first and second walls, the surfaces being angularly offset from one another along a periphery of the block, including applying a coarse balancing procedure to the block;

making the surfaces reflective;

mating the block to a motor; and

applying a precise balancing procedure to the block, the procedure including;

imparting rotation to the block, and

removing material from the block via the first wall using high-energy laser pulses.

2. The method of claim 1, further comprising installing the block and the motor to which the block is mated in a scanner.

3. The method of claim 2, wherein the precise balancing procedure is applied to the block after the block and the motor are installed in the scanner.

4. The method of claim 3, wherein the forming of the block and the making of the surfaces reflective occur prior to installing the block and the motor to which the block is mated in the scanner.

5. The method of claim 1, wherein forming the block during the coarse balancing procedure includes using a shaft-balancing machine.

6. The method of claim 1, wherein making the surfaces reflective includes using surface replication.

7. The method of claim 1, further comprising using drilling for coarse balancing of the block, prior to using the high-energy laser pulses.

8. The method of claim 1, wherein forming the block includes using a hollowed-out substrate to reduce the weight of the block.

9. The method of claim 1, wherein forming the block includes using a glass substrate, a plastic, a polycarbonate, a metal, carbon fiber, or a ceramic.

10. The method of claim 1, wherein removing the material from the block includes removing the material by laser ablation using the high-energy laser pulses.

11. The method of claim 1, wherein removing the material from the block includes:

receiving, at the controller, a feedback signal from an electronic sensor, the signal being indicative of rotation of the block; and

activating and de-activating a laser that emits the high-energy laser pulses, using a controller, in accordance with the feedback signal.

12. A method of manufacturing highly balanced rotatable polygon mirrors for use in scanners, the method comprising:

installing, in a housing of a lidar scanner, an assembly including (i) a coarsely balanced block, the block having a first wall, a second wall, and a plurality of reflective surfaces extending between the first and second walls, the surfaces being angularly offset from one another along a periphery of the block, (ii) a motor mated to the coarsely balanced block;

causing the motor to impart rotation to the block;

removing material from the block via the first wall using a first laser configured to emit high-energy laser pulses, to transform the coarsely balanced block into a highly balanced block;

subsequent to removing the material from the block, installing remaining one or more components of the lidar scanner in the housing, including not removing the assembly including the highly balanced block and the motor.

13. The method of claim 12, wherein installing the assembly further includes installing a polygon mirror axle extending into the coarsely balanced block through at least one of the first and second walls, about which the coarsely balanced block rotates.

14. The method of claim 12, further comprising:

prior to installing the assembly, applying a coarse balancing procedure to the block.

15. The method of claim 14, wherein applying the coarse balancing procedure to the block includes using a shaft-balancing machine.

16. The method of claim 14, wherein applying the coarse balancing procedure to the block includes using drilling.

17. The method of claim 12, further comprising:

prior to installing the assembly, making the surfaces reflective using surface replication.

18. The method of claim 12, further comprising forming the block prior to installing the assembly, wherein forming the block includes using a hollowed-out substrate to reduce the weight of the block.

19. The method of claim 12, further comprising forming the block, wherein forming the block includes using at least one of a glass substrate, a plastic, a polycarbonate, a metal, carbon fiber, or a ceramic.

20. The method of claim 12, wherein removing the material from the block includes:

receiving, at the controller, a feedback signal from an electronic sensor, the signal being indicative of rotation of the block; and

activating and de-activating a laser that emits the high-energy laser pulses, using a controller, in accordance with the feedback signal.