ILLUMINATION LIGHT PROJECTION FOR A DEPTH CAMERA

• US 20140049610A1
• Filed: 08/14/2012
• Published: 02/20/2014
• Est. Priority Date: 08/14/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Masalkar, Prafulla, Hudman, Joshua Mark
• Granted Patent: US 9,297,889 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

Various embodiments of TOF depth cameras and methods for illuminating image environments with illumination light are provided herein. In one example, a TOF depth camera configured to collect image data from an image environment illuminated by illumination light includes a light source including a plurality of surface-emitting lasers configured to generate coherent light. The example TOF camera also includes an optical assembly configured to transmit light from the plurality of surface-emitting lasers to the image environment and an image sensor configured to detect at least a portion of return light reflected from the image environment.

Claims

1. A time-of-flight depth camera configured to collect image data from an image environment illuminated by illumination light, the time-of-flight depth camera comprising:

a light source including a plurality of surface-emitting lasers configured to generate coherent light, the light source comprising an arrangement of the plurality of surface-emitting lasers in a selected shape;

a lens system configured to project an image of the light source to the image environment, the lens system comprising;

a first stage positioned to condense light received from the light source, and

a second stage positioned to receive light from the first stage, the second stage being configured to relay the image of the light source into the image environment to illuminate the image environment; and

an image sensor configured to detect at least a portion of return light reflected from the image environment.

2. The time-of-flight depth camera of claim 1, where the plurality of surface-emitting lasers are arranged in a rectangular shape.

3. The time-of-flight depth camera of claim 1, wherein the lens system is configured to transmit collimated light emitted from a first surface-emitting laser to the image environment in a different direction than collimated light emitted from a second surface-emitting laser.

4. The time-of-flight depth camera of claim 1, where at least one of the plurality of surface-emitting lasers is selected from the group consisting of vertical external cavity surface-emitting lasers (VECSELs) and vertical-cavity surface-emitting lasers (VCSELs).

5. The time-of-flight depth camera of claim 1, where the lens system has an f-number configured to provide an illumination depth region of at least 0.5 m.

6. The time-of-flight depth camera of claim 1, further comprising a Schmidt plate positioned at an entrance pupil of the lens system.

7. The time-of-flight depth camera of claim 1, where each of the plurality of surface-emitting lasers generates coherent light having an angular divergence of 2 degrees or more.

8. The time-of-flight depth camera of claim 1, where the lens system includes a single substrate having a light receiving surface configured to receive light from the light source and a light emitting surface configured to transmit light to the image environment, where the light receiving surface includes a first pattern encoding a first prescription for the first stage, and where the light emitting surface includes a second pattern encoding a second prescription for the second stage.

9. The time-of-flight depth camera of claim 1, where the first stage is further configured to shape the coherent light into light having a light profile that is more intense at a location farther from an optical axis of the light than at a location closer to the optical axis of the light.

10. A time-of-flight depth camera configured to collect image data from an image environment illuminated by illumination light, the time-of-flight depth camera comprising:

a light source including an array of surface-emitting lasers configured to generate coherent light;

a homogenizing light guide positioned to receive at least a portion of coherent light from the light source, the homogenizing light guide being configured to increase an apparent size of the light source;

a microlens array positioned to receive at least a portion of the light emitted from the homogenizing light guide, the microlens array adapted to diverge the light received from the homogenizing light guide for projection into the image environment as illumination light; and

an image sensor configured to detect at least a portion of return light reflected from the image environment.

11. The time-of-flight depth camera of claim 10, where the homogenizing light guide is further configured to defocus the coherent light to generate collimated light.

12. The time-of-flight depth camera of claim 10, where at least one of the plurality of surface-emitting lasers is selected from the group consisting of vertical external cavity surface-emitting lasers (VECSELs) and vertical-cavity surface-emitting lasers (VCSELs).

13. The time-of-flight depth camera of claim 10, where each of the plurality of surface-emitting lasers generates coherent light having an angular divergence of 2 degrees or more.

14. The time-of-flight depth camera of claim 10, where the homogenizing light guide includes a homogenizing light wedge having a total internal reflection surface opposite the light emitting surface, the total internal reflection surface being angled with respect to the light emitting surface.

15. The time-of-flight depth camera of claim 10, where the homogenizing light guide includes a partial internal reflection surface at the light emitting surface and a total internal reflection surface opposite the partial internal reflection surface.

16. The time-of-flight depth camera of claim 10, where the microlens array is further configured to shape the light received from the homogenizing light guide into light having a light profile that is more intense at a location farther from an optical axis of the light than at a location closer to the optical axis of the light.

17. A peripheral time-of-flight depth camera system configured to collect image data from an image environment illuminated by illumination light, the peripheral time-of-flight depth camera comprising:

a light source including a plurality of surface-emitting lasers configured to generate coherent light;

a reflective light guide including a folded light path that receives at least a portion of the coherent light from the light source and emits all of the portion of the coherent light received, the reflective light guide configured to self-correct one or more reflection errors via total internal reflection;

a microlens array positioned to receive at least a portion of the light emitted from the reflective light guide, the microlens array adapted to diverge the light received from the reflective light guide for projection into the image environment as illumination light;

an image sensor configured to detect at least a portion of return light reflected from the image environment;

a logic subsystem; and

a storage subsystem holding instructions executable by the logic subsystem to generate depth information about the object based upon image information generated by the image sensor from detected return light and to output the depth information to a computing device.

18. The peripheral time-of-flight depth camera system of claim 17, where the microlens array is further configured to shape the light received from the reflective light guide into illumination light having a light profile that is more intense farther from an optical axis of the illumination light than closer to the optical axis of the illumination light.

19. The peripheral time-of-flight depth camera system of claim 17, where the reflective light guide includes:

a light entrance configured to receive at least a portion of coherent light from the light source;

a first total internal reflection surface configured to receive all of the coherent light from the light entrance;

a second total internal reflection surface configured to receive all of the coherent light reflected from the first total internal reflection surface; and

a light exit configured to emit all of the coherent light reflected from the second total internal reflection surface.

20. The peripheral time-of-flight depth camera system of claim 17, where at least one of the plurality of surface-emitting lasers is selected from the group consisting of vertical external cavity surface-emitting lasers (VECSELs) and vertical-cavity surface-emitting lasers (VCSELs), and where at least one of the plurality of surface-emitting lasers generates coherent light having an angular divergence of 2 degrees or more.