Calibration system and method for imaging flash LIDAR systems

• US 8,368,876 B1
• Filed: 10/14/2009
• Issued: 02/05/2013
• Est. Priority Date: 10/17/2008
• Status: Active Grant

• Current Assignee: Odyssey Space Research, LLC
• Original Assignee: Odyssey Space Research, LLC
• Inventors: Johnson, Michael D., Andrews, Dwight E.
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US12/579,145
• Time in Patent Office: 1,210 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

Systems and methods for calibrating a LIDAR unit. In one embodiment, a system includes a light pulse detection unit, a delay unit and a two-dimensional target. The light pulse detection unit receives a light pulse from the LIDAR unit. The delay unit produces one or more delayed light pulses which are delayed by a known interval from the light pulse received from the LIDAR unit. The delayed light pulses are used to illuminate the target. Target illumination from each of the delayed light pulses returns to the LIDAR unit with a corresponding known delay. The delay of each delayed light pulse simulates a range that is greater than the actual physical distance from the LIDAR unit to the target. The delay of the light pulses from different parts of the target may be different to simulate different ranges for the different parts of the target.

Claims

1. A system for calibrating a Light Detection and Ranging (LIDAR) unit, the system comprising:

a light pulse detection unit configured to receive a first light pulse from the LIDAR unit;

a delay unit coupled to the light pulse detection unit and configured to produce one or more delayed light pulses, wherein each of the delayed light pulses is delayed by a corresponding known interval from the first light pulse received from the LIDAR unit; and

a target having at least two dimensions, wherein the target is configured to be illuminated by the delayed light pulses, thereby creating corresponding return light pulses, wherein different portions of the target at different positions within a field of view of the LIDAR unit produce different ones of the return light pulses, and wherein the different portions of the target delay the corresponding ones of the return light pulses by different, known amounts of time, wherein each of the return light pulses is returned from the corresponding portion of the target to the LIDAR unit with a corresponding known total delay.

2. The system of claim 1, wherein the known delay corresponding to each of the delayed light pulses is greater than a time required for light to traverse a physical distance from the LIDAR unit to the target and back to the LIDAR unit.

3. The system of claim 1, wherein the target comprises a plurality of two-dimensional target images, and wherein the system further comprises a light tube configured to combine the plurality of two-dimensional target images into a single combined two-dimensional image that is presented to the LIDAR unit.

4. The system of claim 1, further comprising a lens configured to adjust a field of view of the target as presented to the LIDAR unit.

5. The system of claim 1, wherein the delay unit comprises a first length of optical fiber coupled to receive the light pulse from the LIDAR unit and to transmit the light pulse from the LIDAR unit to the target as at least one of the one or more delayed light pulses.

6. The system of claim 5, further comprising one or more optical splitters and one or more additional optical fibers, wherein the optical splitters are configured to split a light pulse emitted from the first length of optical fiber into a first plurality of light pulses, and wherein each of the first plurality of light pulses is transmitted through one or more of the additional optical fibers, thereby imparting a corresponding range gate delay.

11. The system of claim 1, wherein the target comprises a three-dimensional object, and wherein the delayed light pulses are reflected off the three-dimensional object to create the target illumination that is returned to the LIDAR unit.

12. The system of claim 1, wherein the target comprises one or more two-dimensional optical modulators.

13. The system of claim 12, wherein the optical modulators comprise transmissive optical modulators.

14. The system of claim 12, wherein the optical modulators comprise reflective optical modulators.

7. A system for calibrating a Light Detection and Ranging (LIDAR) unit, the system comprising:

a light pulse detection unit configured to receive a light pulse from the LIDAR unit;

a delay unit coupled to the light pulse detection unit and configured to produce one or more delayed light pulses, wherein each of the delayed light pulses is delayed by a corresponding known interval from the light pulse received from the LIDAR unit; and

a target having at least two dimensions, wherein the target is configured to be illuminated by the delayed light pulses, wherein target illumination from each of the delayed light pulses is returned to the LIDAR unit with a corresponding known delay,

wherein the delay unit comprises an electronic controller and a light source, wherein the electronic controller is triggered by the light pulse from the LIDAR unit, wherein the electronic controller is configured to control the light source to generate the one or more delayed light pulses at the corresponding known intervals after being triggered by the light pulse received from the LIDAR unit.

8. The system of claim 7, wherein the electronic controller is configured to control the light source to generate the one or more delayed light pulses in succession, with each of the delayed light pulses separated from adjacent ones of the delayed light pulses by a range gate delay.

9. The system of claim 8, wherein each of the delayed light pulses is modulated by one or more two-dimensional optical modulators, thereby presenting a series of range gate images to the LIDAR unit.

10. The system of claim 7, further comprising one or more optical shutters, wherein the optical shutters are configured to gate a single delayed light pulse generated by the light source to produce multiple delayed light pulses.

15. A system for calibrating a Light Detection and Ranging (LIDAR) unit, the system comprising:

a light pulse detection unit configured to receive a light pulse from the LIDAR unit;

a delay unit coupled to the light pulse detection unit and configured to produce one or more delayed light pulses, wherein each of the delayed light pulses is delayed by a corresponding known interval from the light pulse received from the LIDAR unit; and

a target having at least two dimensions, wherein the target is configured to be illuminated by the delayed light pulses, wherein target illumination from each of the delayed light pulses is returned to the LIDAR unit with a corresponding known delay,

wherein the delay unit comprises an electronic controller and a light source, wherein the electronic controller is triggered by the light pulse from the LIDAR unit, wherein the electronic controller is configured to control the light source to scan a beam generated by the light source across entrance apertures of a plurality of optical fibers, wherein each of the optical fibers carries a corresponding light pulse to the target.

16. The system of claim 15, wherein the beam is scanned across the entrance apertures of the optical fibers sequentially to create a range gate delay between light pulses of successive ones of the optical fibers.

17. The system of claim 16, wherein the entrance apertures of the optical fibers are arranged in a linear array.

18. The system of claim 17, wherein the beam is a linearly expanded beam, and wherein an angle between the linearly expanded beam and the linear array of entrance apertures is adjustable to vary the range gate delay between light pulses of successive ones of the optical fibers.

19. A method for calibrating a Light Detection and Ranging (LIDAR) unit, the method comprising:

emitting a first light pulse from the LIDAR unit;

receiving the first light pulse from the LIDAR unit in a light pulse detection unit;

generating one or more delayed light pulses, wherein each of the delayed light pulses is delayed by a corresponding known interval from the first light pulse received from the LIDAR unit;

illuminating a target having at least two dimensions with the delayed light pulses, thereby creating corresponding return light pulses, wherein different portions of the target at different positions within a field of view of the LIDAR unit produce different ones of the return light pulses, and wherein the different portions of the target delay the corresponding ones of the return light pulses by different, known amounts of time;

receiving each of the return light pulses at the LIDAR unit with a corresponding known total delay; and

adjusting a range calibration of the LIDAR unit based on the known total delay corresponding to each of the return light pulses.