Systems And Methods Of High Resolution Three-Dimensional Imaging

• US 20100128109A1
• Filed: 11/25/2009
• Published: 05/27/2010
• Est. Priority Date: 11/25/2008
• Status: Active Grant

• Current Assignee: Nlight Inc.
• Original Assignee: Tetravue Inc.
• Inventors: Banks, Paul S.
• Granted Patent: US 8,471,895 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• 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 17/89 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 7/4816 of receivers alone
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/486 Receivers
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: H04N 13/204 using stereoscopic image cameras stereoscopic photography G03B35/00
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof

Abstract

Embodiments of the invention provide systems and methods for three-dimensional imaging with wide field of view and precision timing. In accordance with one aspect, a three-dimensional imaging system includes an illumination subsystem configured to emit a light pulse with a divergence sufficient to irradiate a scene having a wide field of view. A sensor subsystem is configured to receive over a wide field of view portions of the light pulse reflected or scattered by the scene and including: a modulator configured to modulate as a function of time an intensity of the received light pulse portion to form modulated received light pulse portions; and means for generating a first image corresponding to the received light pulse portions and a second image corresponding to the modulated received light pulse portions. A processor subsystem is configured to obtain a three-dimensional image based on the first and second images.

Claims

1. A three-dimensional imaging system, comprising:

an illumination subsystem configured to emit a light pulse with a divergence sufficient to irradiate a scene having a wide field of view;

a sensor subsystem configured to receive over a wide field of view portions of the light pulse reflected or scattered by the scene, the sensor subsystem comprising;

a modulator configured to modulate as a function of time an intensity of the received light pulse portions to form modulated received light pulse portions; and

means for generating a first image corresponding to the received light pulse portions and a second image corresponding to the modulated received light pulse portions; and

a processor subsystem configured to obtain a three-dimensional image based on the first and second images.

2. The system of claim 1, wherein the means for generating comprises first and second discrete arrays of light sensors.

3. The system of claim 2, wherein the means for generating further comprises an image constructor.

4. The system of claim 1, wherein the means for generating comprises a single array of light sensors.

5. The system of claim 1, wherein the light pulse has a duration of less than 2 nanoseconds.

6. The system of claim 1, wherein the divergence is between 1 and 180 degrees.

7. The system of claim 1, wherein the divergence is between 5 and 40 degrees.

8. The system of claim 1, wherein the illumination subsystem comprises a low-coherence laser configured to generate light pulses containing a sufficient number of spatial modes to produce a smooth spatial profile.

9. The system of claim 1, wherein the light pulse contains a wavelength between 1400 nm and 2500 nm.

10. The system of claim 1, wherein the modulator comprises a Pockels cell.

11. The system of claim 1, wherein the processor subsystem comprises a controller configured to send a control signal to the modulator, the modulator configured to modulate the received light pulse portions monotonically as a function of time responsive to the control signal.

12. The system of claim 1, wherein the processor subsystem comprises a controller configured to send a control signal to the modulator, the modulator configured to modulate the received light pulse portions non-monotonically as a function of time responsive to the control signal.

13. The system of claim 1, wherein the means for generating includes at least one focal plane array comprising a plurality of pixels, each pixel having a well depth of 100,000 or more electrons.

14. The system of claim 1, wherein the means for generating includes at least one focal plane array comprising a plurality of pixels, and further comprising a filter having a plurality of regions, each region positioned in front of a pixel and configured to attenuate light transmitted to that pixel in a predetermined fashion.

15. The system of claim 1, wherein the sensor subsystem further comprises a broadband or multiband imaging subsystem, the imaging subsystem comprising:

an image sensor configured to obtain a broadband or multiband image of the scene; and

an optic configured to direct a portion of the received light to the image sensor.

16. The system of claim 1, wherein at least one of the first and second images contains a region of maximum intensity, wherein the means for generating comprises a sensor array having a saturation limit, and wherein the system is configured to enhance a dynamic range of the three-dimensional image by increasing an energy of the light pulse above the saturation limit of the sensor array.

17. The system of claim 1, wherein the processor subsystem is configured to:

instruct the illumination subsystem to emit a plurality of light pulses;

adjust a timing of the modulator such that modulation begins at a different time for each light pulse of the plurality of light pulses;

obtain a plurality of three-dimensional images corresponding to each light pulse of the plurality of light pulses; and

obtain an enhanced three-dimensional image based on the plurality of three-dimensional images, the enhanced three-dimensional image corresponding to a larger distance window than a distance window of any of the plurality of three-dimensional images.

18. A method of three-dimensional imaging, comprising:

emitting a light pulse having a divergence sufficient to irradiate a scene having a wide field of view;

receiving over a wide field of view portions of the light pulse reflected or scattered by the scene;

modulating with a modulator the received light pulse portions as a function of time to form modulated received light pulse portions;

generating a first image corresponding to the received light pulse portions;

generating a second image corresponding to the modulated received light pulse portions; and

obtaining a three-dimensional image of the scene based on the first and second images.

19. The method of claim 18, wherein generating the first image comprises adding the second image to a third image.

20. The method of claim 18, wherein modulating with the modulator comprises modulating a polarization state of the received light pulse portions.