Methods and Systems for LIDAR Optics Alignment

• US 20160282453A1
• Filed: 03/27/2015
• Published: 09/29/2016
• Est. Priority Date: 03/27/2015
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Pennecot, Gaetan, Droz, Pierre-yves
• Granted Patent: US 9,651,658 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4972 Alignment of sensor
• CPC Class Codes: G01S 7/51 Display arrangements
• CPC Class Codes: G02B 27/62 Optical apparatus specially adapted for adjusting optical elements during the assembly of optical systems
• CPC Class Codes: G02B 5/20 Filters polarising elements G02B5/30

Abstract

A method is provided that involves mounting a transmit block and a receive block in a LIDAR device to provide a relative position between the transmit block and the receive block. The method also involves locating a camera at a given position at which the camera can image light beams emitted by the transmit block and can image the receive block. The method also involves obtaining, using the camera, a first image indicative of light source positions of one or more light sources in the transmit block and a second image indicative of detector positions of one or more detectors in the receive block. The method also involves determining at least one offset based on the first image and the second image. The method also involves adjusting the relative position between the transmit block and the receive block based at least in part on the at least one offset.

Claims

1. A method comprising:

mounting a transmit block and a receive block in a light detection and ranging (LIDAR) device to provide a relative position between the transmit block and the receive block, wherein the transmit block includes one or more light sources configured to emit light at a source wavelength, and wherein the receive block includes one or more detectors configured to detect light at the source wavelength;

locating a camera at a given position at which the camera, when focused at infinity, can image light beams emitted by the one or more light sources and can image the one or more detectors;

obtaining a first image using the camera located at the given position and focused at infinity, wherein the first image is indicative of light source positions of the one or more light sources;

obtaining a second image using the camera located at the given position and focused at infinity, wherein the second image is indicative of detector positions of the one or more detectors in the receive block;

determining at least one offset based on the light source positions indicated by the first image and the detector positions indicated by the second image; and

adjusting the relative position between the transmit block and the receive block based at least in part on the at least one offset.

2. The method of claim 1, wherein the LIDAR device further includes a lens configured to (i) collimate light emitted from the one or more light sources and (ii) focus light onto the one or more detectors, and wherein the given position is such that the camera can image light beams emitted by the one or more light sources via the lens and can image the one or more detectors via the lens.

3. The method of claim 1, wherein adjusting the relative position between the transmit block and the receive block comprises:

rotating the receive block about an axis.

4. The method of claim 1, wherein obtaining the first image comprises:

obtaining the first image while the one or more light sources are emitting light at the source wavelength.

5. The method of claim 4, wherein obtaining the first image further comprises:

obtaining the first image while a light filter is interposed between the camera and the one or more light sources, wherein the light filter is configured to attenuate light within a wavelength range that includes the source wavelength.

6. The method of claim 1, wherein obtaining the second image comprises:

obtaining the second image while the one or more light sources are not emitting light at the source wavelength and the one or more detectors are illuminated with light at the source wavelength from an auxiliary light source.

7. The method of claim 1, further comprising generating a composite image based on overlaying the first image and the second image, wherein the at least one offset is determined based on separation between one or more pixels in the composite image associated with a light source and one or more pixels in the composite image associated with a corresponding detector.

8. The method of claim 1, wherein adjusting the relative position between the transmit block and the receive block reduces the at least one offset.

9. The method of claim 1, wherein adjusting the relative position between the transmit block and the receive block causes the at least one offset to correspond to a particular offset.

10. The method of claim 1, further comprising:

detecting a defect in a light source based on the first image.

11. The method of claim 1, further comprising:

detecting an aberration in an optical element optically coupled to a light source based on the first image.

12. The method of claim 1, wherein the receive block is coupled to a half-mirror positioned along a receive path of the receive block, wherein the camera is coupled to at least two light sources positioned along a periphery of a camera lens of the camera and configured to emit light toward the LIDAR device, the method further comprising:

causing the at least two light sources to emit light pulses;

obtaining a third image from the camera indicative of reflections of the emitted light pulses off the half-mirror coupled to the receive block; and

comparing the third image with a stored image, wherein adjusting the relative position between the transmit block and the receive block is further based on the comparison.

13. The method of claim 1, further comprising actuating at least two probes positioned adjacent to the receive block toward the receive block, wherein a given probe is configured to provide a signal indicative of contact between the given probe and the receive block, wherein adjusting the relative position between the transmit block and the receive block comprises rotating the receive block such that at least two signals from the at least two probes are provided at a same time.

14. A system comprising:

a mounting platform to mount a light detection and ranging (LIDAR) device that provides a relative position between a transmit block in the LIDAR device and a receive block in the LIDAR device, wherein the transmit block includes one or more light sources configured to emit light at a source wavelength, wherein the receive block includes one or more detectors configured to detect light at the source wavelength;

a camera located at a given position at which the camera, when focused at infinity, can image light beams emitted by the one or more light sources and can image the one or more detectors;

an alignment apparatus configured to adjust the relative position between the transmit block and the receive block; and

a controller configured to;

obtain a first image from the camera located at the given position and focused at infinity, wherein the first image is indicative of light source positions of the one or more light sources;

obtain a second image from the camera located at the given position and focused at infinity, wherein the second image is indicative of detector positions of the one or more detectors in the receive block;

determine at least one offset based on the light source positions indicated by the first image and the detector positions indicated by the second image; and

cause the alignment apparatus to adjust the relative position between the transmit block and the receive block based at least in part on the at least one offset.

15. The system of claim 14, wherein the LIDAR device further includes a lens configured to (i) collimate light emitted from the one or more light sources and (ii) focus light onto the one or more detectors, and wherein the given position is such that the camera can image light beams emitted by the one or more light sources via the lens and can image the one or more detectors via the lens.

16. The system of claim 14, further comprising:

a light filter configured to attenuate light within a wavelength range that includes the source wavelength; and

an actuator coupled to the light filter, wherein the controller is further configured to;

cause the actuator to move the light filter to a first position where the light filter is interposed between the camera and the one or more light sources;

obtain the first image while the light filter is at the first position;

cause the actuator to move the light filter to a second position where the light filter is outside a field-of-view of the camera; and

obtain the second image while the light filter is at the second position.

17. The system of claim 14, further comprising:

at least two light sources positioned along a periphery of a camera lens of the camera and configured to emit light toward the LIDAR device, wherein the receive block is coupled to a half-mirror positioned along a receive path of the receive block, and wherein the controller is further configured to;

cause the at least two light sources to emit light pulses;

obtain a third image from the camera indicative of reflections of the emitted light pulses off the half-mirror coupled to the receive block; and

adjust the relative position between the transmit block and the receive block based also on the third image.

18. The system of claim 14, further comprising:

at least two probes positioned adjacent to the receive block, wherein a given probe is configured to provide a signal indicative of contact between the given probe and the receive block, and wherein the controller is further configured to;

control an actuator to move the at least two probes toward the receive block; and

cause the alignment apparatus to rotate the receive block such that at least two signals from the at least two probes are provided at a same time.

19. The system of claim 14, wherein causing the alignment apparatus to adjust the relative position between the transmit block and the receive block reduces the at least one offset.

20. The system of claim 14, wherein the controller is further configured to:

detect an aberration in an optical element optically coupled to a light source based on the first image.