Optical system for object detection and location

• US 10,267,915 B2
• Filed: 06/07/2016
• Issued: 04/23/2019
• Est. Priority Date: 06/07/2016
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Uyeno, Gerald P., Keller, Sean D.
• Primary Examiner(s): Bolda, Eric L
• Application Number:
  US15/175,807
• Publication Number:
  US 20170350979A1
• Time in Patent Office: 1,050 Days
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• 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 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• 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: G01S 7/4873 by deriving and controlling a threshold value
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31

Abstract

Optical systems and methods for object detection and location. One example of an optical system includes a laser radar optical source positioned to emit a pulsed laser beam, a non-mechanical beamsteering device positioned to scan the beam in a linear scan over a first area of a scene, a laser radar detector positioned to receive and integrate a reflection of the beam, a read-out integrated circuit (ROIC) configured to provide a first read-out signal based on the integrated reflection, and a controller configured to receive the first read-out signal, determine a range to the first area based on a time of flight of the pulsed laser beam, and identify a presence of an object within the scene based on a signal level of the first read-out signal, the first signal level corresponding to a reflectivity of a portion of the object within the first area of the scene.

Claims

1. An imaging system comprising:

a laser radar optical source positioned to emit a pulsed laser beam along a fixed optical axis;

a non-mechanical beamsteering device positioned along the fixed optical axis to receive the pulsed laser beam from the laser radar optical source and to scan the pulsed laser beam in a first linear scan over a first area of a scene and in a second linear scan over a second area of the scene;

a laser radar detector positioned to receive and integrate, at a first active portion of the laser radar detector, a reflection of the pulsed laser beam from the first area of the scene, and at a second active portion of the laser radar detector, a reflection of the pulsed laser beam from the second area of the scene;

a read-out integrated circuit (ROIC) coupled to the laser radar detector and configured to provide a first read-out signal based at least in part on the integrated reflection of the pulsed laser beam corresponding to the first area of the scene and a second read-out signal based at least in part on the reflection of the pulsed laser beam corresponding to the second area of the scene; and

a controller coupled to the ROIC and configured to;

receive the first read-out signal and the second read-out signal;

determine a range to the first area of the scene based at least in part on a time of flight of the pulsed laser beam of the first linear scan;

determine a range to the second area of the scene based at least in part on a time of flight of the pulsed laser beam of the second linear scan;

identify a presence of an object within the scene based at least in part on a first signal level of the first read-out signal, the first signal level corresponding to a reflectivity of at least a portion of the object within the first area of the scene; and

generate an average signal level for the scene, the average signal level corresponding to an average of at least the first signal level of the first read-out signal and a signal level of the second read-out signal.

2. The imaging system according to claim 1, wherein the controller is further configured to generate an image of the object within the scene based at least in part on the range to the first area of the scene and the range to the second area of the scene.

3. The imaging system according to claim 2, wherein the controller is further configured to detect a spatial profile of the object, and aggregate object data based at least in part on the detected spatial profile.

4. The imaging system according to claim 1, wherein in identifying the presence of the object, the controller is further configured to compare the first signal level and the average signal level for the scene and detect a disparity between the first signal level and the average signal level.

5. The imaging system according to claim 1, wherein the non-mechanical beamsteering device is further configured to synchronize at least the first linear scan to correspond to the first active portion of the laser radar detector.

6. The imaging system according to claim 5, wherein the photodetector includes a single linear array of detector elements.

7. The imaging system according to claim 1, wherein the non-mechanical beamsteering device, the laser radar detector, and the ROIC are configured to operate in accordance with a search and track mode of operation, and wherein during the search and track mode of operation the non-mechanical beamsteering device and laser radar detector are synchronized.

8. A method for optical imaging, the method comprising:

emitting from a laser radar optical source a pulsed laser beam along a fixed optical axis;

scanning with a non-mechanical beamsteering device the pulsed laser beam in a first linear scan over a first area of a scene;

receiving and integrating, at a first active portion of a laser radar detector, a reflection of the pulsed laser beam from the first area of the scene;

scanning with the non-mechanical beamsteering device the pulsed laser beam in a second linear scan over a second area of the scene;

receiving and integrating, at a second active portion of the laser radar detector, a reflection of the pulsed laser beam from the second area of the scene;

providing a first read-out signal from a read-out integrated circuit (ROIC) coupled to the laser radar detector, the first read-out signal being based at least in part on the integrated reflection of the pulsed laser beam corresponding to the first area of the scene;

providing a second read-out signal from the ROIC based at least in part on a reflection of the pulsed laser beam corresponding to the second area of the scene;

determining a range to the first area of the scene based at least in part on a time of flight of the pulsed laser beam of the first linear scan;

determining a range to the second area of the scene based at least in part on a time of flight of the pulsed laser beam of the second linear scan;

identifying whether an object is present within the scene based at least in part on a first signal level of the first read-out signal, the first signal level corresponding to a reflectivity of at least a portion of the object within the first area of the scene, by generating an average signal level for the scene corresponding to an average of at least the first signal level of the first read-out signal and a second signal level of the second read-out signal, comparing the first signal level and the average signal level, and detecting a disparity between the first signal level and the average signal level.

9. The method according to claim 8, further comprising generating an image of the object based at least in part on the range to the first area of the scene and the range to the second area of the scene.

10. The method according to claim 9, further comprising:

detecting a spatial profile of the object; and

aggregating object data based at least in part on the detected spatial profile.

11. An imaging system comprising:

a laser radar optical source positioned to emit a pulsed laser beam;

a non-mechanical beamsteering device positioned to receive the pulsed laser beam from the laser radar optical source, the non-mechanical beamsteering device being configured to scan the pulsed laser beam in a first linear scan over a first area of a scene including at least a portion of an object, and in a second linear scan over a second area of the scene;

a laser radar detector positioned to receive and integrate, at a first active portion of the laser radar detector, a reflection of the pulsed laser beam from the first area of the scene, and at a second active portion of the laser radar detector, a reflection of the pulsed laser beam from the second area of the scene, wherein a boresight of the laser radar detector is fixed to a line of sight of an operator;

a read-out integrated circuit (ROIC) coupled to the laser radar detector and configured to provide a first read-out signal based at least in part on the integrated reflection of the pulsed laser beam corresponding to the first area of the scene and a second read-out signal based at least in part on the reflection of the pulsed laser beam corresponding to the second area of the scene;

a controller coupled to the ROIC and configured to receive the first and second read-out signals, determine a range to the first portion of the object based at least in part on a time of flight of the pulsed laser beam of the first linear scan, determine a range to the second area of the scene based at least in part on a time of flight of the pulsed laser beam of the second linear scan, identify a presence of the object within the scene based at least in part on a first signal level of the first read-out signal, the first signal level corresponding to a reflectivity of the portion of the object within the first area of the scene, and generate an average signal level for the scene, the average signal level corresponding to an average of at least the first signal level of the first read-out signal and a signal level of the second read-out signal; and

a housing configured to couple the imaging system to the operator.

12. The imaging system according to claim 11, wherein the housing includes at least one of a goggle housing, a vehicle-mount housing, and a machinery-mount housing.

13. The imaging system according to claim 11, wherein the non-mechanical beamsteering device, the laser radar detector, and the ROIC, are configured to operate in accordance with a search and track mode of operation, and wherein during the search and track mode of operation the non-mechanical beamsteering device and laser radar detector are synchronized.

14. The imaging system according to claim 11, wherein in identifying the presence of the object, the controller is further configured to compare the first signal level and the average signal level for the scene and detect a disparity between the first signal level and the average signal level.