Distributed LIDAR with fiber optics and a field of view combiner

• US 10,564,266 B2
• Filed: 12/21/2017
• Issued: 02/18/2020
• Est. Priority Date: 09/25/2016
• Status: Active Grant

• Current Assignee: O'Keeffe, James Thomas
• Original Assignee: O'Keeffe, James Thomas
• Inventors: O'Keeffe, James Thomas
• Primary Examiner(s): Murphy, Daniel L
• Application Number:
  US15/851,686
• Publication Number:
  US 20190025412A1
• Time in Patent Office: 789 Days
• Field of Search: 356 401
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

Large time-of-flight photodetector arrays can be expensive and one solution is to multiplex the detector array between several distinct fields of view, thereby increasing its utilization. In one embodiment, a vehicle-based distributed LIDAR is disclosed, comprising a plurality of coherent fiber optic image bundles (CFOBs) that transfer laser reflections from several fields of view (FOVs) around the vehicle to a shared remotely located detector array. An optical combiner functions to multiplex (e.g. timeshares) the FOVs from each coherent fiber bundle onto the remote detector array. Individual fibers in the CFOBs gather laser reflections from distinct portions of a FOV, thereby enabling correlation of the original reflection directions with fiber locations within a bundle. Unlike single fiber cables or incoherent multicore fiber cables, where the direction of incoming light is lost, the CFOBs transfer both the timing and direction of laser reflections from multiple FOVs to a shared detector array.

Claims

1. A light detection and ranging system comprising:

a. one or more emitters to generate an outgoing set of light pulses;

b. a plurality of coherent fiber optic image bundles (CFOBs) each comprising;

a plurality of optical fibers;

an input surface; and

an output surface;

wherein the plurality of optical fibers have a common spatial sequence at both the input surface and the output surface, and

wherein each of the plurality of CFOBs is positioned to transport at least some of a set of light reflections corresponding to the outgoing set of light pulses, from the corresponding input surface to the corresponding output surface;

c. one or more lenses to focus light on the input surface of each of the plurality of CFOBs; and

d. a ranging subassembly comprising;

a detector that functions to detect the set of light reflections;

a field of view combiner positioned relative to the output surface of each of the plurality of CFOBs to combine the set of light reflections at the detector;

electronic circuitry to compute for the set of light reflections a corresponding set of 3D reflection locations; and

a controller to instruct the one or more emitters to generate the outgoing set of light pulses.

2. The light detection and ranging system of claim 1 wherein the detector is a 2D detector array;

and

wherein the field of view combiner is a spatial field of view combiner that functions to transmit for each CFOB in the plurality of CFOBs, the corresponding at least some of the set of light reflections from the corresponding output surface to a corresponding portion of the 2D detector array dedicated to the each CFOB.

3. The light detection and ranging system of claim 1 wherein the field of view combiner is a solid state switchable mirror multiplexor.

4. The light detection and ranging system of claim 1 wherein the field of view combiner is a mechanical optical multiplexor.

5. The light detection and ranging system of claim 1 wherein the field of view combiner is a micromirror array multiplexor.

6. The light detection and ranging system of claim 1 wherein the field of view combiner is a fiber optic taper.

7. The light detection and ranging system of claim 1 wherein a first subset of the set of light reflections are carried exclusively by a first CFOB from the plurality of CFOBs and a second subset of the set of light reflections are carried exclusively by a second CFOB from the plurality of CFOBs and

wherein the field of view combiner functions to time multiplex the detector between receiving the first and second subsets of set of light reflections.

8. The light detection and ranging system of claim 7 wherein the detector comprises a plurality of detector elements arranged in 2D array;

and

wherein the field of view combiner is positioned relative to the detector such that each of the plurality of detector elements is operable to receive a light reflection from the first subset of the set of light reflections and a light reflection from the second subset of the set of light reflections.

9. The light detection and ranging system of claim 1 wherein for a first CFOB in the plurality of CFOBs the plurality of optical fibers comprises at least some optical fibers with a first cross-section area and at least some optical fibers with a second cross-section area distinct from the first cross-section area thereby providing variable resolution from the first CFOB.

10. The light detection and ranging system of claim 1 wherein a first CFOB of the plurality of CFOBs extends a length between the input surface and output surface;

and further comprises at least one expanded end wherein at least some of the plurality of optical fibers have a larger cross-section at the expanded end than at a point along the length.

11. The light detection and ranging system of claim 1 wherein the CFOB has a packing fraction at the input surface of at least 50 percent.

12. The light detection and ranging system of claim 1 wherein the plurality of CFOBs functions to transmit the set of light reflections to the ranging subassembly with positions at the output surfaces of the plurality of CFOBs that indicate the set of reflection directions at the input surfaces of the plurality of CFOBs.

13. The light detection and ranging system of claim 1 further comprising an optical connector to connect a first CFOB in the plurality of CFOBs to the ranging subassembly and wherein the optical connector comprises a registration feature to align the output surface of the first CFOB relative to the ranging subassembly in a specific orientation.

14. A light detection and ranging system comprising:

a. one or more emitters that generate an outgoing set of light pulses;

b. a first and a second coherent fiber optic image bundle (CFOB) each comprising;

an input surface,

one or more lenses,

an output surface, and

a plurality of optical fibers, fused together in a common spatial arrangement at both the input surface and the output surface,

wherein the plurality of optical fibers transfer, at least some of a set of light reflections corresponding to the outgoing set of light pulses from the input surface to the output surface;

wherein each of the set of light reflections is from a corresponding reflection location in a set of reflection locations; and

c. a ranging subassembly comprising;

a detector array that detects the set of light reflections,

a field of view combiner that combines the set of light reflections from the output surfaces of the first and second CFOBs at the detector array;

electronic circuitry coupled to the detector array that computes, for each light reflection in the set of light reflections a 3D location, indicative of the corresponding reflection location; and

a controller to instruct the one or more emitters to generate the outgoing set of light pulses.

15. The light detection and ranging system of claim 14 wherein the detector comprises a plurality of detector elements arranged in 2D array;

and

wherein the field of view combiner is positioned relative to the detector such that each of the plurality of detector elements receives at least one light reflection in the set of light reflections from the first CFOB and at least one light reflection in the set of light reflections from the second CFOB.

16. The light detection and ranging system of claim 14 wherein the detector comprises a plurality of detector elements arranged in 2D array;

and

wherein the field of view combiner is positioned relative to the detector such that each of the plurality of detector elements is operable to receive light reflections from the first CFOB and the second CFOB.

17. The light detection and ranging system of claim 14 wherein the first CFOB is a flexible CFOB, such that the plurality of optical fibers are arranged in a common spatial arrangement at the input surface and the output surface;

and wherein the plurality of optical fibers have a variable spatial arrangement along an elongated center section between the input surface and the output surface of the first CFOB.

18. The light detection and ranging system of claim 14 wherein the detector array further comprises a first detector element operable to receive light reflections in the set of light reflections from both the first and second CFOBs and wherein the field of view combiner functions at least in part to alternate between providing the light reflections in the set of light reflections from the first CFOB and providing the light reflections in the set of light reflections carried by the second CFOB to the first detector element.

19. The light detection and ranging system of claim 14 wherein the detector array generates a set of reflection signals indicating for each light reflection in the set of reflections a corresponding arrival time;

wherein at least some of the electronic circuitry computes for each light reflection in the set of light reflections a corresponding distance to the corresponding reflection location using the corresponding arrival time and uses the corresponding distance to compute the corresponding 3D location indicative of the corresponding reflection location.

20. The light detection and ranging system of claim 14 wherein for at least one of the first and second CFOBs the corresponding plurality of optical fibers is elongated and has a length of at least one meter between the input and output surface.

21. The light detection and ranging system of claim 14 wherein each of the first and second CFOBs has a corresponding field of view (FOV) comprising a set of directions in which the each of the first and second CFOBs can receive at the corresponding input surface light reflections corresponding to the outgoing set of light pulses, and

wherein for each of the first and second CFOBs the ranging subassembly is remotely located from the corresponding FOV.

22. The light detection and ranging system of claim 21 wherein for the second CFOB the corresponding FOV is a narrower subset of the FOV corresponding to the first CFOB,

wherein the first CFOB provides a first subset of the set of light reflections to the ranging subassembly;

and

wherein the second CFOB provides to the ranging subassembly a second subset of the set of light reflections that has a higher resolution than the first subset of the set of light reflections.

23. The light detection and ranging system of claim 14 further comprising;

a lens that functions for the first CFOB to focus light onto the input surface and

a positioning mechanism that positions the lens and input surface of the first CFOB and thereby determines a field of view for the first CFOB.

24. A method comprising:

a. generating with one or more emitters an outgoing set of light pulses;

b. for each of a plurality of coherent fiber optic image bundles (CFOBs), each comprising an input surface, an output surface and a plurality of optical fibers;

focusing at least some of a set of light reflections corresponding to the outgoing set of light pulses on the input surface using a lens and transporting in the plurality of optical fibers, from the input surface to the output surface, the at least some of the set of light reflections corresponding to the outgoing set of light pulses, comprising the step of;

maintaining, using a common spatial ordering of the plurality of optical fibers at the input surface and the output surface, a common spatial ordering of the at least some of the set of light reflections at both the input surface and the output surface;

c. combining with a field of view (FOV) combiner, the set of light reflections from the output surfaces of the plurality of CFOBs;

d. detecting with a detector coupled to the field of view combiner the set of light reflections, wherein the detector comprises a 2D array of detector elements, and wherein combining the set of light reflections further comprises condensing the set of light reflections to fit onto the 2D array of detector elements; and

e. with electronic circuitry coupled to the detector, computing for each of the set of light reflections a corresponding 3D location indicative of a corresponding reflection location.

25. Method claim of claim 24 wherein the FOV combiner functions to alternate between transmitting a first some of the set of light reflections from the first CFOB to the detector with a first angular resolution and transmitting a second some of the set of light reflections from the second CFOB to the detector with a second finer angular resolution.

26. The method of claim 24 further comprising the step of controlling a position of a subassembly comprising the lens and the input surface of a first CFOB from the plurality of CFOBs to control at least one aspect of at least a first subset of the set of light reflections, from a group of aspects consisting of an angular range of the first subset of the set of light reflections, the angular resolution of the first subset of the set of light reflections, or the field of view corresponding to the first subset of the set of light reflections.

27. The method of claim 24 further comprising the steps of:

configuring the field of view combiner to transmit a first plurality of the set of light reflections from a first CFOB of the plurality of CFOBs to the detector;

computing for each light reflection in the first plurality of the set of light reflections the corresponding 3D location using a first local origin corresponding to the first CFOB; and

subsequently, reconfiguring the field of view combiner to transmit a second plurality of the set of light reflections from a second CFOB of the plurality of CFOBs to the detector; and

computing for each light reflection in the second plurality of the set of light reflections the corresponding 3D location using a second local origin corresponding to the second CFOB.

28. The method of claim 24 further comprising the steps of:

computing for each light reflection in a first subset of the set of light reflections, from a first CFOB of the plurality of CFOBs, the corresponding 3D location using a first local origin indicative of a location of the input surface of the first CFOB; and

computing for each light reflection in a second subset of the set of light reflections, from a second CFOB of the plurality of CFOBs, the corresponding 3D location using a second local origin indicative of a location of the input surface of the second CFOB.