HIGH DYNAMIC RANGE & DEPTH OF FIELD DEPTH CAMERA

• US 20130201288A1
• Filed: 02/01/2013
• Published: 08/08/2013
• Est. Priority Date: 02/03/2012
• Status: Active Grant

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: An-Chun Tien, Bryed Billerbeck
• Inventors: BILLERBECK, Bryed, TIEN, An-Chun, MORALES, Lucas
• Granted Patent: US 9,294,754 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• 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 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: H04N 13/204 using stereoscopic image cameras stereoscopic photography G03B35/00

Abstract

In order to maximize the dynamic range and depth of field for a depth camera used in a time of flight system, the light source is modulated at a plurality of different frequencies, a plurality of different peak optical powers, a plurality of integration subperiods, a plurality of lens foci, aperture and zoom settings during each camera frame time. The different sets of settings effectively create subrange volumes of interest within a larger aggregate volume of interest, each having their own frequency, peak optical power, lens aperture, lens zoom and lens focus products consistent with the distance, object reflectivity, object motion, field of view, etc. requirements of various ranging applications.

Claims

1. A depth camera for a time of flight device for presenting three dimensional data to a host comprising:

a light source for launching a beam of light at a range of interest for a field of view, the light source having an adjustable frequency and an adjustable peak optical power;

a detector array for receiving and detecting portions of the beam of light reflected off of objects within the range of interest and field of view; and

a controller for adjusting the light source frequency and peak optical power within a single frame time period in accordance with a plurality of frequency and peak optical power pairs to obtain a plurality of three dimensional data measurements for each frame time period,

whereby the range of interest and field of view is divided into a plurality of volumes of interest, each volume of interest having a different, frequency, peak optical power, and minimum and maximum distance from the light source, to increase dynamic range and depth of field within each volume of interest.

2. The depth camera according to claim 1, wherein initial light source frequency and peak optical power settings for each volume of interest are predetermined and stored in non-volatile memory accessible by the controller.

3. The depth camera according to claim 2, wherein the controller adjusts at least one of the light source frequency and the peak optical power based on feedback from the detector array.

4. The depth camera according to claim 1, wherein the controller also adjusts the light source integration period in accordance with predetermined or calculated integration periods for each frequency and peak optical power pair.

5. The depth camera according to claim 4, further comprising a lens for focusing the beam of light;

wherein the controller is also capable of adjusting the focus of the lens along with each frequency, peak optical power and integration period.

6. The depth camera according to claim 5, further comprising an adjustable aperture for the lens;

wherein the controller is also capable of adjusting the adjustable aperture along with each frequency, peak optical power, integration period and lens focus.

7. The depth camera according to claim 1, further comprising an adjustable lens for focusing the beam of light;

wherein the controller is also capable of adjusting the focus of the lens along with each frequency and peak optical power.

8. The depth camera according to claim 1, further comprising a lens and an adjustable aperture for the lens;

wherein the controller is also capable of adjusting the adjustable aperture along with each frequency and peak optical power pair.

9. The depth camera according to claim 1, wherein the controller is also capable of aggregating the plurality of three dimensional data measurements

10. The depth camera according to claim 9, further comprising an ASIC incorporating the controller and other control and processing functions of the camera to minimize latency between the depth camera and the host device.

11. The depth camera according to claim 1, wherein the controller is also capable of dynamically adjusting any one or more of the frequencies, and the peak optical powers depending on a reflectivity of the object.

12. The depth camera according to claim 1, wherein a first frequency is between 10 and 40 MHz, and a first peak optical power is greater than 1 W.

13. The depth camera according to claim 1, wherein a second frequency is between 40 and 50 MHz, and a second peak optical power is between 250 mW and 1 W.

14. The depth camera according to claim 1, wherein a third frequency is greater than 75 MHz, and a third peak optical power is less than 250 mW.

15. A method of operating a depth camera comprising:

a) launching light from a light source at a range of interest over a field of view; and

b) receiving and detecting portions of the beam of light reflected off of various objects within the range of interest and the field of view;

wherein step a) includes;

launching a first beam of light at a first frequency and a first peak optical power for a first integration period within a single frame time period to increase depth of field and dynamic range within a first volume of interest to generate a first three dimensional data measurement,

launching a second beam of light at a second frequency greater than the first frequency and a second peak optical power less than the first peak optical power for a second integration period within the same single frame time period to increase depth of field and dynamic range within a second volume of interest to generate a second three dimensional data measurement; and

launching a third beam of light at a third frequency greater than the second frequency and a third peak optical power less than the second peak optical power for a third integration period within the same single frame time period to increase depth of field and dynamic range within a third volume of interest to generate a third three dimensional data measurement.

16. The method according to claim 15, wherein step b) including aggregating the first, second and third three dimensional data measurements.

17. The method according to claim 15, further comprising adjusting the focus of a lens associated with the light source for each of the first, second and third volumes of interest.

18. The method according to claim 15, further comprising adjusting an aperture of a lens associated with the light source for each of the first, second and third volumes of interest.

19. The method according to claim 15, further comprising dynamically adjusting any one or more of the first, second and third frequencies, and the first, second and third peak optical powers depending on a reflectivity of one of the objects.

20. The method according to claim 15, wherein the first, second and third integration periods are different.

21. The method according to claim 15, wherein the first frequency is between 20 and 25 MHz, and the first peak optical power is greater than 500 mW.

22. The method according to claim 15, wherein the second frequency is between 40 and 50 MHz, and the second peak optical power is between 250 and 500 mW.

23. The method according to claim 15, wherein the third frequency is greater than 60 MHz, and the third peak optical power is less than 250 mW.

24. A time of flight based depth camera for presenting three dimensional data to a host device comprising:

a light source for launching a beam of light at a range of interest for a field of view, the light source having variable integration time periods and peak optical power;

a detector array for receiving and detecting portions of the beam of light reflected off of objects within the range of interest and field of view; and

a controller for adjusting the light source integration time period and peak optical power within a single frame time period in accordance with a plurality of integration time period and peak optical power pairs to obtain a plurality of three dimensional data measurements, whereby the range of interest and field of view is divided into a plurality of volumes of interest, each volume of interest having a different, integration time period, peak optical power, and minimum and maximum distance from the light source, to increase dynamic range and depth of field within each volume of interest.