ELECTRONICALLY STEERED FLASH LIDAR

• US 20120038903A1
• Filed: 08/16/2010
• Published: 02/16/2012
• Est. Priority Date: 08/16/2010
• Status: Active Grant

• Current Assignee: Ball Aerospace & Technologies Corporation (Ball Corporation)
• Original Assignee: Ball Aerospace & Technologies Corporation (Ball Corporation)
• Inventors: Weimer, Carl S., Ramond, Tanya M., Adkins, Carl M., Applegate, Jeff T., Delker, Thomas P., Ruppert, Lyle S.
• Granted Patent: US 8,736,818 B2
• Time in Patent Office: Days
• US Class Current: 356/4.07
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor

Abstract

Methods and systems for adaptively controlling the illumination of a scene are provided. In particular, a scene is illuminated, and light reflected from the scene is detected. Information regarding levels of light intensity received by different pixels of a multiple pixel detector, corresponding to different areas within a scene, and/or information regarding a range to an area within a scene, is received. That information is then used as a feedback signal to control levels of illumination within the scene. More particularly, different areas of the scene can be provided with different levels of illumination in response to the feedback signal.

Claims

1. A method for illuminating a scene, comprising:

outputting light in a first illumination pattern, wherein the first illumination pattern illuminates the scene;

determining at least one of an intensity of light reflected from the scene while the scene is illuminated by the first illumination pattern or a range to an area of the scene determined from light included in the first illumination pattern;

in response to detecting the at least one of an intensity of light reflected from the scene as a result of illumination of the scene by the first illumination pattern or a range to an area of the scene determined from light included in the first illumination pattern, outputting a second illumination pattern and illuminating the scene with the second illumination pattern, wherein the first illumination pattern differs from the second illumination pattern.

2. The method of claim 1, wherein the first illumination pattern comprises a first plurality of beams, wherein the second illumination pattern comprises a second plurality of beams, and wherein outputting the second plurality of beams includes steering at least one of the beams included in the first plurality of beams.

3. The method of claim 2, wherein outputting the second plurality of beams includes controlling at least a first beam included in the first plurality of beams, and wherein controlling at least a first beam included in the first plurality of beams includes at least one of:

controlling an intensity of the first beam,

controlling an area within in the scene on which the first beam is incident, and

controlling an area adjacent the scene on which the first beam is incident.

4. The method of claim 1, wherein the second illumination pattern is output in response to detecting an intensity of light received at a first element of a multiple element detector as a result of illumination of the scene by the first illumination pattern.

5. The method of claim 1, wherein detecting an intensity of light reflected from the scene while the scene is illuminated by the first illumination pattern includes receiving a signal from at least a first element of a multiple element detector.

6. The method of claim 5, wherein the signal received from the first element of the multiple element detector is greater than a threshold amount,

wherein a signal received from a second element of the multiple element detector is less than the threshold amount,

wherein producing a second illumination pattern includes reducing an intensity of a first beam illuminating area of the scene from which light received by the first element of the multiple element detector is reflected as compared to the intensity of a corresponding beam in the first illumination pattern, and

wherein producing a second illumination pattern does not include reducing an intensity of a second beam illuminating an area of the scene from which light received by the second element of the multiple element detector is reflected as compared to the intensity of a corresponding beam in the first illumination pattern.

7. The method of claim 5, further comprising:

directing the second illumination pattern to the scene;

in response to detecting that an intensity of light reflected from the scene while the scene is illuminated by the second illumination pattern exceeds a threshold amount, controlling the second illumination pattern to produce a third illumination pattern, wherein the second illumination pattern differs from the third illumination pattern.

8. The method of claim 5, wherein the intensity of light detected by the first element of the multiple element detector while the scene is illuminated by the second illumination pattern is less than the intensity of light detected by the first element of the multiple element detector while the scene is illuminated by the first illumination pattern.

9. The method of claim 2, wherein controlling the first plurality of beams includes steering a first one of the beams independently of a second one of the plurality of beams.

10. The method of claim 1, wherein controlling the first illumination pattern includes electronically controlling the first illumination pattern.

11. An imaging system, comprising:

a light source;

a multiple pixel detector;

a controller, wherein at least one of a number of beams output by the imaging system forming device, a differential power of beams output by the imaging system, and a number of beams incident on a scene from which light is reflected to the multiple pixel detector is controlled by the controller in response to a signal from at least a first pixel included in the multiple pixel detector.

12. The system of claim 11, wherein the light source includes a laser or an array of lasers.

13. The system of claim 12, further comprising:

a beam forming device, wherein the beam forming device is an acoustic optic modulator.

14. The system of claim 13, further comprising:

a driver circuit, wherein the driver circuit provides a first number of drive frequencies to the acoustic optic modulator, and wherein the beam forming device outputs a number of beams equal to the first number of drive frequencies plus one.

15. The system of claim 14, wherein the driver circuit changes an amplitude of at least one of the first number of drive frequencies to change an intensity of one of the beams included in the first number of beams.

16. The system of claim 11, wherein the multiple pixel detector is a focal plane array.

17. The system of claim 11, wherein the beam forming device is operable to produce multiple beams including at least first and second beams, and wherein the first beam has a different intensity than the second beam.

18. A lidar system, including:

a light source, wherein the light source generates at least a first light pulse comprising a first beam of light;

a first acoustic optic modulator, wherein the beam of light generated by the light source is provided to the first acoustic optic modulator;

a first radio frequency driver, wherein a selected number of radio frequencies are output to the first acoustic optic modulator, and wherein a number of steerable beams corresponding to the selected number of radio frequencies are output from the first acoustic optic modulator in response to the selected number of radio frequencies;

a focal plane array;

a controller, wherein the controller is in communication with at least the light source, the first radio frequency driver, and the focal plane array, wherein a time at which the first light pulse is generated by the light source and a time at which a return signal comprising at least some light from the first light pulse is received at the focal plane array provides range information, wherein information regarding an intensity of the return signal is provided to the controller, and wherein the information regarding an intensity of the return signal is used to determine at least one parameter of a control signal provided by the controller to the first radio frequency driver.

19. The system of claim 18, wherein the at least one parameter of a control signal includes an intensity of a first steerable beam output from the first acoustic optic modulator and an intensity of a second steerable beam output from the first acoustic optic modulator, wherein the intensity of the first steerable beam relative to the second steerable beam is changed between the first light pulse generated by the light source and a second pulse generated by the light source.

20. The system of claim 18, wherein the at least one parameter of a control signal includes a steering angle of first, second and third steerable beams output from the first acoustic optic modulator, wherein the first steerable beam is steered independently of the second and third steerable beams.