Microrod compression of laser beam in combination with transmit lens

• US 9,086,273 B1
• Filed: 03/08/2013
• Issued: 07/21/2015
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Gruver, Daniel, Droz, Pierre-Yves, Pennecot, Gaetan, Morriss, Zachary, Iordache, Dorel Ionut
• Primary Examiner(s): Alsomiri, Isam
• Assistant Examiner(s): Abraham, Samantha K
• Application Number:
  US13/790,251
• Time in Patent Office: 865 Days
• Field of Search: 356/3.01, 356/4.01, 356/4.07, 356/5.01, 356/5.09, 356/9, 356/625
• US Class Current: 1/1
• CPC Class Codes: G01C 3/02 Details
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• 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 7/4817 relating to scanning

Abstract

A LIDAR device may transmit light pulses originating from one or more light sources and may receive reflected light pulses that are detected by one or more detectors. The LIDAR device may include a lens that both (i) collimates the light from the one or more light sources to provide collimated light for transmission into an environment of the LIDAR device and (ii) focuses the reflected light onto the one or more detectors. Each light source may include a respective laser diode and cylindrical lens. The laser diode may emit an uncollimated laser beam that diverges more in a first direction than in a second direction. The cylindrical lens may pre-collimate the uncollimated laser beam in the first direction to provide a partially collimated laser that diverges more in the second direction than in the first direction.

Claims

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

at least one laser diode, wherein the at least one laser diode is configured to emit an uncollimated laser beam comprising light in a narrow wavelength range, wherein the uncollimated laser beam has a first divergence in a first direction and a second divergence in a second direction, and wherein the first divergence is greater than the second divergence;

at least one cylindrical lens, wherein the at least one cylindrical lens is configured to pre-collimate the uncollimated laser beam in the first direction to provide a partially collimated laser beam that has a third divergence in the first direction and a fourth divergence in the second direction, wherein the third divergence is less than the fourth divergence and the fourth divergence is substantially equal to the second divergence;

at least one detector, wherein the at least one detector is configured to detect light having wavelengths in the narrow wavelength range; and

an objective lens, wherein the objective lens is configured to (i) collimate the partially collimated laser beam to provide a collimated laser beam for transmission into an environment of the LIDAR device and (ii) focus object-reflected light onto the at least one detector, wherein the object-reflected light comprises light from the collimated laser beam that has reflected from one or more objects in the environment of the LIDAR device.

2. The LIDAR device of claim 1, wherein the objective lens receives the partially collimated laser beam via a transmission path and focuses the object-reflected light through a focusing path, and wherein the transmission path includes a reflective element that partially obstructs the focusing path.

3. The LIDAR device of claim 2, wherein the reflective element comprises a plane mirror.

4. The LIDAR device of claim 1, wherein the at least one laser diode comprises a plurality of laser diodes, the at least one detector comprises a plurality of detectors, and the at least one cylindrical lens comprises a plurality of cylindrical lenses, such that each cylindrical lens in the plurality of cylindrical lenses is associated with a corresponding laser diode in the plurality of laser diodes.

5. The LIDAR device of claim 4, wherein each laser diode is configured to emit a respective uncollimated laser beam in a respective direction, and wherein each cylindrical lens is configured to pre-collimate the uncollimated laser beam produced by its corresponding laser diode to provide a corresponding partially collimated laser beam that is then collimated by the objective lens to provide a corresponding collimated laser beam.

6. The LIDAR device of claim 5, wherein each detector in the plurality of detectors is associated with a corresponding laser diode in the plurality of laser diodes, and wherein the objective lens is configured to focus onto each detector a respective portion of the object-reflected light that comprises light from the detector'"'"'s corresponding laser diode.

7. The LIDAR device of claim 6, wherein each laser diode has a rectangular aperture that has a short dimension and a long dimension, and wherein each cylindrical lens is configured to magnify the short dimension of the aperture of its corresponding laser diode such that the light from the laser diode that is focused onto the laser diode'"'"'s corresponding detector has a substantially square shape.

8. The LIDAR device of claim 1, wherein the at least one cylindrical lens comprises at least one microrod lens.

9. The LIDAR device of claim 1, wherein the narrow wavelength range includes wavelengths of about 905 nanometers.

10. The LIDAR device of claim 1, wherein the objective lens is an aspherical lens.

11. The LIDAR device of claim 1, further comprising a mirror, wherein the mirror is configured to reflect the collimated laser beam from the objective lens into the environment and to reflect the object-reflected light from the environment into the objective lens.

12. The LIDAR device of claim 11, wherein the mirror rotates about a vertical axis.

13. The LIDAR device of claim 12, wherein the mirror comprises a plurality of reflective surfaces, each reflective surface having a different tilt with respect to the vertical axis.

14. A light detection and ranging (LIDAR) device, comprising:

a plurality of light sources, wherein each light source is configured to emit partially collimated light;

a plurality of detectors, wherein each detector in the plurality of detectors is associated with a respective light source in the plurality of light sources;

a first mirror, wherein the first mirror is configured to reflect the partially collimated light from the light sources;

a second mirror, wherein the second mirror is configured to rotate about an axis; and

a lens, wherein the lens is configured to (i) receive, via the first mirror, the partially collimated light from the light sources, (ii) collimate the partially collimated light from the light sources to provide collimated light, wherein the second mirror is configured to reflect the collimated light from the lens into an environment of the LIDAR device, and (iii) focus, via a focusing path, onto each detector any object-reflected light from the detector'"'"'s associated light source that has reflected from one or more objects in the environment of the LIDAR device, wherein the second mirror is configured to reflect the object-reflected light from the environment into the lens,

wherein the first mirror partially obstructs the focusing path.

15. The LIDAR device of claim 14, wherein each light source in the plurality of light sources comprises a respective laser diode and a respective cylindrical lens.

16. The LIDAR device of claim 14, wherein the second mirror comprises a plurality of reflective surfaces, each reflective surface having a different tilt with respect to the axis.

17. A method comprising:

emitting an uncollimated laser beam from a laser diode, wherein the uncollimated laser beam has a first divergence in a first direction and a second divergence in a second direction, and wherein the first divergence is greater than the second divergence;

pre-collimating the uncollimated laser beam in the first direction to provide a partially collimated laser beam, wherein the partially collimated laser beam has a third divergence in the first direction and a fourth divergence in the second direction, and wherein the third divergence is less than the fourth divergence and the fourth divergence is substantially equal to the second divergence;

collimating, by a lens, the partially collimated laser beam to provide a collimated laser beam;

transmitting the collimated laser beam into an environment;

collecting object-reflected light, wherein the object-reflected light comprises light from the collimated laser beam that has reflected from one or more objects in the environment; and

focusing, by the lens, the object-reflected light through a focusing path onto a detector, wherein the lens receives the partially collimated laser beam via a plane mirror that partially obstructs the focusing path.

18. The method of claim 17, wherein pre-collimating the uncollimated laser beam in the first direction to provide a partially collimated laser beam comprises transmitting the uncollimated laser beam through a cylindrical lens.

19. The method of claim 17, wherein transmitting the collimated laser beam into an environment comprises a rotating mirror reflecting the collimated laser beam from the lens into the environment, and wherein collecting object-reflected light comprises the rotating mirror reflecting the object-reflected light from the environment into the lens.

20. The method of claim 17, further comprising:

rotating an optical assembly about an axis while transmitting the collimated laser beam into the environment and collecting object-reflected light, wherein the optical assembly includes the laser diode, the lens, the detector, and the plane mirror.