Efficient lidar with flexible target interrogation pattern

• US 7,532,311 B2
• Filed: 04/06/2005
• Issued: 05/12/2009
• Est. Priority Date: 04/06/2005
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Postal Technologies Inc (Opex Corporation)
• Original Assignee: Lockheed Martin Coherent Technologies, Inc. (Martin Marietta Corporation)
• Inventors: Henderson, Sammy W., Suni, Paul J. M.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US11/100,082
• Publication Number:
  US 20060227317A1
• Time in Patent Office: 1,497 Days
• Field of Search: 356/28, 356/4.01, 356/614, 356/622, 382/210, 382/154, 382/106
• US Class Current: 356/4.01
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A system for observing a field of view including a light transmitter and a light detector. A path is defined between the transmitter and the detector. The light transmitter generates substantially coherent light onto a transmit portion of a light path and the light detector is positioned in a receive portion of the light path defined by reflected light from some of the target locations. The system includes a component for configuring at least a portion of the light path such that a subset of the plurality of potential target points are included in the light path.

Claims

1. A system for observing a field of view, wherein the field of view comprises a plurality of potential target points, the system comprising:

a transmitter;

a detector comprising a plurality of detector elements, wherein a path is defined between the transmitter and the detector,

wherein the transmitter is configured to generate electromagnetic (EM) energy into a transmit portion of the path,

wherein the detector is positioned in a receive portion of the path defined by reflected EM energy from some of the plurality of potential target points;

a beam forming element configured to select at least one of a plurality of illumination patterns, to selectively generate M beams out of N possible beams to produce an illumination pattern, and to illuminate simultaneously a selected subset of the plurality of potential target points in the field of view using M beams out of N possible beams, the subset including multiple predetermined areas within the field of view, wherein M is an integer, N is an integer, and M is less than N; and

a second beam forming element positioned in the receive portion of the path, the second beam forming element configured to select a subset of the plurality of detector elements and to steer the receive portion of the path to the selected subset of the plurality of detector elements.

2. The system of claim 1 wherein the beam forming element is positioned in the transmit portion of the path.

3. The system of claim 1 further comprising, means for configuring at least a portion of the path such that the subset of the plurality of potential target points are to be included in the path, wherein the means for configuring comprises the beam forming element.

4. The system of claim 3 further comprising a signal processor coupled to the detector and operable to process signals generated by the detector, wherein the signal processor is coupled to the means for configuring at least a portion of the path to select a subset of the plurality of detector elements for processing.

5. The system of claim 3 further comprising a local oscillator (LO) for producing a laser beam aligned with the receive portion of the path to implement coherent detection.

6. The system of claim 5 wherein the LO is configured to use the means for configuring at least a portion of the path.

7. The system of claim 5 further comprising a second means for configuring at least a portion of the path, wherein the LO is configured to use the second means for configuring.

8. The system of claim 3 wherein the means for configuring at least a portion of the path comprises fixed passive elements.

9. The system of claim 3 wherein the means for configuring at least a portion of the path comprises switchable passive elements.

10. The system of claim 3 wherein the means for configuring at least a portion of the path comprises active elements.

11. The system of claim 3 wherein the means for configuring at least a portion of the path comprises a device selected from the group consisting of:

liquid, crystal array, deformable mirror, micro-mirror array, micro-prism array, transmissive phase control devices, diffractive optical devices, refractive optical devices and holograms.

12. The system of claim 1 wherein the beam forming element is configured to alter one or more characteristics of the EM energy selected from the group consisting of:

direction, phase, frequency, amplitude and polarization.

13. The system of claim 1 wherein the beam forming element is configured to alter one or more characteristics of the reflected EM energy selected from the group consisting of:

direction, phase, frequency, amplitude and polarization.

14. The system of claim 1 further comprising a signal processor coupled to the detector and operable to process signals generated by the detector.

15. The system of claim 1 wherein the detector comprises a number of elements that is larger than the number in the subset of the plurality of potential target points.

16. The system of claim 1 wherein the detector comprises a number of elements that is substantially equal to the number in the subset of the plurality of potential target points.

17. The system of claim 1 wherein the detector comprises a number of elements that is less than the number in the subset of the plurality of potential target points.

18. The system of claim 1 wherein the selected subset of the plurality of potential target points comprises a selectable two-dimensional pattern.

19. The system of claim 1 wherein the beam forming element is configured to illuminate a first selected pattern of the plurality of potential target points and to move the first selected pattern to fill in a second selected pattern of the plurality of potential target points over a predetermined period of time, wherein the second selected pattern is larger than the first selected pattern.

20. The system of claim 1 wherein the selected subset of the plurality of potential target points comprises three sub-areas, 6×

6 sub-areas, or larger sub-areas.

21. The system of claim 1 wherein the beam forming element is configured to produce non-parallel independently pointing beams.

22. The system of claim 1 wherein the beam forming element is programmable to produce a selectable illumination pattern, and the second beam forming element is programmable to flexibly select a subset of the plurality of detector elements.

23. The system of claim 1 wherein the beam forming element is configured to produce an arbitrary illumination pattern.

24. The system of claim 1 wherein there is no one-to-one relationship between M beams and the number of active pixels in the detector.

25. The system of claim 1 wherein the beam forming element and the second beam forming element are mounted as a beam forming subsystem having a common mechanical carrier or housing,

wherein the beam forming element and the second beam forming element are aligned relative to one another in the common mechanical carrier or housing off-line, and

wherein the beam forming subsystem is configured to be field replaceable in that the beam forming subsystem is configured to be interchangeable in a field as a unit with a second pre-aligned beam forming subsystem, without performing in the field alignment of multiple elements of the second pre-aligned beam forming subsystem.

26. A method for observing a field of view, wherein the field of view comprises a plurality of potential target points, the method comprising:

transmitting electromagnetic (EM) energy into a transmit portion of a path;

directing the light path to the field of view, wherein some of the EM energy in the path is reflected to form a receive portion of the path, the step of directing comprising;

selecting at least one of a plurality of illumination patterns;

selectively generating M beams out of N possible beams to produce an illumination pattern, wherein M is an integer, N is an integer, and M is less than N; and

illuminating simultaneously a selected subset of the plurality of potential target points in the field of view using M beams out of N possible beams, the subset including multiple predetermined areas within the field of view; and

detecting the reflected EM energy, the step of detecting comprising;

selecting a subset of a plurality of detector elements; and

steering the receive portion of the path to the selected subset of the plurality of detector elements.

27. A method comprising using the method of claim 26 to determine a characteristic of an object in the field of view.

28. The method of claim 27 wherein the characteristic is selected from the group consisting of:

range, speed, velocity, acceleration, direction of motion, vibration, texture, reflectivity, color, dimension and shape.

29. The method of claim 26 further comprising configuring at least a portion of the path such that the subset of the plurality of potential target points are included in the path,

wherein the act of configuring at least a portion of the path comprises:

configuring the transmit portion of the path to direct the path to only selected location in the field of view.

30. The method of claim 29 wherein the act of configuring at least a portion of the path further comprises:

configuring the receive portion of the path to direct the receive portion of the path to selected portions of a detector used to perform the detecting.

31. The method of claim 29 wherein the act of configuring the path further comprises altering one or more characteristics of the EM energy selected from the group consisting of:

direction, phase, frequency, amplitude and polarization.

32. A system for observing a field of view, wherein the field of view comprises a plurality of potential target points, the system comprising:

a transmitter;

a detector comprising a plurality of detector elements, wherein a path is defined between the transmitter and the detector,

wherein the transmitter is configured to generate electromagnetic (EM) energy into a transmit portion of the path,

wherein the detector is positioned in a receive portion of the path defined by reflected EM energy from some of the plurality of potential target points;

a beam forming element configured to select at least one of a plurality of illumination patterns, to selectively generate M beams out of N possible beams to produce an illumination pattern, and to illuminate simultaneously a selected subset of the plurality of potential target points in the field of view using M beams out of N possible beams, the subset including multiple predetermined areas within the field of view, wherein M is an integer, N is an integer, and M is less than N; and

a detector controller coupled to the detector, the detector controller configured to receive information as to which of the plurality of detector elements are valid and to enable data output from only the plurality of detector elements that contain valid data.