MODULAR LADAR SENSOR

• US 20140340487A1
• Filed: 01/23/2013
• Published: 11/20/2014
• Est. Priority Date: 01/23/2013
• Status: Active Grant

• Current Assignee: Continental Autonomous Mobility US LLC (Continental AG)
• Original Assignee: Advanced Scientific Concepts, Inc.
• Inventors: Gilliland, Patrick, Heughebaert, Laurent, Spagnolia, Joseph, Short, Brad, Stettner, Roger
• Granted Patent: US 9,277,204 B2
• Time in Patent Office: Days
• US Class Current: 348/48
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: H04N 13/167 Synchronising or controlling image signals
• CPC Class Codes: H04N 13/172 image signals comprising non-image signal components, e.g. headers or format information
• CPC Class Codes: H04N 13/25 using two or more image sensors with different characteristics other than in their location or field of view, e.g. having different resolutions or colour pickup characteristics; using image signals from one sensor to control the characteristics of another sensor

Abstract

A lightweight, low volume, inexpensive LADAR sensor incorporating 3-D focal plane arrays is adapted specifically for modular manufacture and rapid field configurability and provisioning. The present invention generates, at high speed, 3-D image maps and object data at short to medium ranges. The techniques and structures described may be used to extend the range of long range systems as well, though the focus is on compact, short to medium range ladar sensors suitable for use in multi-sensor television production systems and 3-D graphics capture and moviemaking. 3-D focal plane arrays are used in a variety of physical configurations to provide useful new capabilities.

Claims

1. A modular ladar sensor comprising:

a receiver module within a housing, said housing having a quick connect optical receiver coupling, said housing further having a laser transmitter electrical connector and a laser transmitter mechanical mount for rapidly mounting a laser transmitter module;

a lens assembly with a quick connect optical plug coupling which mates with said optical receiver coupling;

a laser transmitter module with an electrical connector adapted to engage and mate with said laser transmitter electrical connector, and with complementary mechanical mounting and fastening features which mate with said laser transmitter mechanical mount, said laser transmitter with a modulated laser light output and a diffusing optic for illuminating a scene in the field of view of said modular ladar sensor;

a two dimensional array of light sensitive detectors positioned at a focal plane of said lens assembly, each of said light sensitive detectors with an output producing an electrical response signal from a reflected portion of said modulated laser light output;

a readout integrated circuit with a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having an input connected to one of said light sensitive detector outputs, each unit cell electrical circuit having an electrical response signal demodulator and a range measuring circuit connected to an output of said electrical response signal demodulator, said range measuring circuit further connected to a reference signal providing a zero range reference for the said range measuring circuit;

and,

a detector bias circuit connected to at least one voltage distribution grid of said array of light sensitive detectors, and a temperature stabilized frequency reference.

2. The modular ladar sensor of claim 1 wherein said quick connect optical receiver coupling comprises a bayonet style mount.

3. The modular ladar sensor of claim 1 wherein said laser transmitter electrical connector is a keyed connector.

4. The modular ladar sensor of claim 1 wherein said laser transmitter electrical connector further comprises optical connector contacts.

5. The modular ladar sensor of claim 1 wherein said complementary mechanical mounting and fastening features are comprised of clearance holes and screws.

6. The modular ladar sensor of claim 1 wherein said modulated laser light output comprises pulsed laser light.

7. The modular ladar sensor of claim 1 wherein said modulated laser light comprises sinewave modulated laser light.

8. The modular ladar sensor of claim 1 wherein said array of light sensitive detectors is formed on a semiconductor film on a sapphire substrate.

9. The modular ladar sensor of claim 8 wherein said sapphire substrate further comprises a microlens array.

10. A modular ladar sensor unit with a field of view and a wavelength of operation, said modular ladar sensor unit further comprising:

a laser transmitter with

a modulated laser light output and a diffusing optic for illuminating a scene in the field of view of a modular ladar sensor, and

a two dimensional array of light sensitive detectors positioned at a focal plane of a light collecting and focusing system, each of said light sensitive detectors having an output producing an electrical response signal from a reflected portion of said modulated laser light output,

a readout integrated circuit with a plurality of unit cell electrical circuits, each of said unit cell electrical circuits having

an input connected to one of said light sensitive detector outputs,

an electrical response signal demodulator, and

a range measuring circuit connected to an output of said electrical response signal demodulator, and said range measuring circuit further connected to a reference signal providing a zero range reference for said range measuring circuit;

a detector bias circuit connected to at least one voltage distribution grid of said array of light sensitive detectors, and a temperature stabilized frequency reference;

a communications port providing range data from said range measuring circuits of said unit cell electrical circuits; and

,

a keyed electrical connector connected to said communications port and quick connect mechanical mount having at least one mating pair of electrical contacts for connection to a host platform.

11. The modular ladar sensor unit of claim 10 wherein said laser transmitter comprises an optically pumped solid state laser formed in a gain medium selected from the set of yttrium aluminum garnet, erbium doped glass, neodymium doped yttrium aluminum garnet, and erbium doped yttrium aluminum garnet.

12. The modular ladar sensor unit of claim 10 wherein said laser transmitter comprises a vertical cavity surface emitting laser formed in a semiconducting gain medium with at least one element selected from the set of indium, gallium, arsenic, phosphorus.

13. The modular ladar sensor unit of claim 10 wherein said modulated laser light output is modulated with a waveform selected from the set of a single Gaussian pulse profile, multiple Gaussian profile pulses, a single flat-topped pulse profile, multiple flat-topped pulses, a pulsed sinewave, and a chirped sinewave pulse.

14. The modular ladar sensor unit of claim 13 wherein said waveform is a sequence of pulses and said sequence of pulses are encoded using a Barker code.

15. The modular ladar sensor unit of claim 10 wherein said two dimensional array of light sensitive detectors is mounted directly to said readout integrated circuit.

16. The modular ladar sensor unit of claim 10 wherein said two dimensional array of light sensitive detectors is formed on a sapphire substrate.

17. The modular ladar sensor unit of claim 10 wherein said two dimensional array of light sensitive detectors is formed of a semiconductor having at least one element selected from the set of silicon, indium, gallium, arsenic, phosphorus, aluminum, boron, antimony, magnesium, germanium, and nitrogen.

18. The modular ladar sensor unit of claim 10 wherein said electrical response signal demodulator comprises:

an input amplifier with an output connected to a trigger circuit;

a series of analog sampling gates, each sampling gate with an associated analog memory cell,

a sample clock controlling the timing of each of said sampling gates, a selector for selecting each of said sampling gates in sequence,

a counter for counting the number of samples,

an output amplifier with an input connected to each of said analog memory cells,

an output control for selecting a sequence of said analog memory cell contents to be output through said output amplifier,

and wherein an input of an analog to digital converter is connected to said output amplifier, an output of said analog to digital converter is connected to an input of a digital processor and produces a sequence of digitized analog samples of said electrical response signal, and said digital processor is programmed to demodulate said electrical response signal by operating on the sequence of digitized analog samples using a digital processing algorithm.

19. The modular ladar sensor unit of claim 10 wherein said electrical response signal demodulator comprises:

an input amplifier with an output connected to a first input of a phase comparator, said phase comparator having a phase reference signal connected to a second input, and an output of said phase comparator connected to the input of an integrator, said integrator having an integrator output with an output voltage proportional to the difference in phase between said first input and said second input of said phase comparator.

20. A 3D vision system comprising:

a host platform having an electronic enclosure with an opening;

a modular ladar sensor with a field of view and a wavelength of operation, said modular ladar sensor mounted in a unit to said host platform through the opening in said electronic enclosure and electrically connected to said host platform through an electrical connector and retained therein by a quick connect and release mechanical feature, said electrical connector having at least one mating pair of electrical contacts, said modular ladar sensor unit incorporating

a laser transmitter with a modulated laser light output and a diffusing optic for illuminating a scene in the field of view of said modular ladar sensor;

a two dimensional array of light sensitive detectors positioned at a focal plane of a light collecting and focusing system, each of said light sensitive detectors with an output producing an electrical response signal from a reflected portion of said modulated laser light outputs;

a readout integrated circuit with a plurality of unit cell electrical circuits, each of said unit cell electrical circuits with an input connected to one of said light sensitive detector outputs, said unit cell electrical circuits each having

an electrical response signal demodulator and

a range measuring circuit connected to an output of said electrical response signal demodulator, said range measuring circuit further connected to a reference signal providing a zero range reference for said range measuring circuit, and,

a detector bias circuit connected to at least one voltage distribution grid of said array of light sensitive detectors, and a temperature stabilized frequency reference.

21. The 3D vision system of claim 20 wherein said host platform further comprises at least one guiding feature selected from the set of guide rails, guide slots, and guide beams.

22. The 3D vision system of claim 20 wherein said modular ladar sensor unit incorporates at least one guiding feature selected from the set of guide rails, guide slots, and guide beams.

23. The 3D vision system of claim 20 wherein said host platform further comprises a conductive cover secured to said opening in said electronic enclosure.

24. The 3D vision system of claim 20 wherein said host platform further comprises a hinged conductive door designed to open into a recessed cavity within said electronic enclosure.

25. The 3D vision system of claim 20 wherein an outer surface of said modular ladar sensor unit is a conductive surface.

26. The 3D vision system of claim 20 further comprising a housing which is formed from a processed material selected from the set of bent sheet metal, cast metal alloy, forged metal alloy, and molded plastic.

27. The 3D vision system of claim 26 wherein said housing has a surface treated by a process selected from the set of electroplating, chemical film application, zinc coating, chromate coating, evaporated metallic coating applied under vacuum, electroless plating, physical vapor deposition, sputtering, and flame spray.

28. The 3D vision system of claim 20 wherein said host platform having an electronic enclosure further has an opening therein, and said opening with a conductive cover attached thereto, and a conductive gasket applied between said conductive cover and a surface of said electronic enclosure.

29. The 3D vision system of claim 20 wherein said host platform having an electronic enclosure further has an opening therein, and a plurality of conductive spring fingers connecting between a surface of said opening and a conductive surface of a modular ladar sensor unit inserted within said opening.

30. A three dimensional video production system capable of capturing three dimensional images comprising:

a master controller and

a plurality of ladar sensors, each ladar sensor having a field of view overlapping a common scene of interest to be imaged,

each ladar sensor connected to said master controller via a signal transmission cable,

each ladar sensor having an internal real time clock, and

each ladar sensor time stamping an acquired three dimensional image file with the time given by said real time clock, and

a scene processor receiving three dimensional images from said plurality of ladar sensors, said scene processor producing a solid model of said common scene of interest by combining time stamped three dimensional images received from said plurality of ladar sensors.

31. The three dimensional video production system of claim 30 wherein each of said ladar sensors receives a real time clock reference signal from a satellite in earth orbit.

32. The three dimensional video production system of claim 30 wherein said master controller further comprises a master real time clock and a transmission cable length measuring system, and said master controller distributing an individually cable length adjusted real time clock to each of said ladar sensors, and each of said plurality of ladar sensors thereby maintaining a real time clock synchronous with said master real time clock.

33. The three dimensional video production system of claim 30 wherein each of said ladar sensors is mounted to a two dimensional imaging device, and said two dimensional imaging device is further mounted to a pointing platform with at least two angular degrees of freedom.

34. The three dimensional video production system of claim 33 wherein said pointing platform has a motorized pivot for each angular degree of freedom.

35. The three dimensional video production system of claim 34 wherein said motorized pivots work together with a controller to track an object of interest.

36. The three dimensional video production system of claim 30 wherein each of said ladar sensors is mounted to a two dimensional imaging device, and said two dimensional imaging device is further mounted to a traversing platform.

37. The three dimensional video production system of claim 36 wherein said traversing platform is selected from the set of a wheeled dolly, a wheeled cart on a track, and a wire supported overhead platform.

38. The three dimensional video production system of claim 37 wherein said wire supported overhead platform comprises a SkyCam®

overhead camera system.

39. The three dimensional video production system of claim 30 wherein said common scene of interest further comprises an object of interest selected from the set of an actor, an athlete, a vehicle, and an object in play.

40. The three dimensional video production system of claim 39 wherein said object of interest further has a feature marked with an attached infrared reflector.