Illumination light projection for a depth camera

Patent metadata

Field	Value
Publication number	US-9891309-B2
Application number	US-201615068479-A
Country	US
Kind code	B2
Filing date	Mar 11, 2016
Priority date	Aug 14, 2012
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

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.

First claim

The invention claimed is:

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 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.

2. The time-of-flight depth camera of claim 1 , where the homogenizing light guide is further configured to defocus the coherent light to generate collimated light.

3. 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).

4. 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.

5. The time-of-flight depth camera of claim 1 , 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.

6. The time-of-flight depth camera of claim 1 , 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.

7. The time-of-flight depth camera of claim 1 , 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.

8. The time-of-flight depth camera of claim 1 , where the microlens array is further configured to shape the light received from the light guide into a profile comprising a rectangular shape.

9. 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.

10. The peripheral time-of-flight depth camera system of claim 9 , 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.

11. The peripheral time-of-flight depth camera system of claim 9 , 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.

12. The peripheral time-of-flight depth camera system of claim 9 , 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.

13. The peripheral time-of-flight depth camera system of claim 9 , 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.

14. 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 comprising a plurality of surface-emitting lasers configured to generate coherent light;
a light guide positioned to receive at least a portion of the coherent light from the light source, the light guide being configured to spread the coherent light within the light guide and to emit the portion of the coherent light;
a microlens array positioned to receive at least a portion of the light emitted from the light guide, the microlens array adapted to diverge the light received from the 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 environment.

15. The time-of-flight depth camera of claim 14 , where the plurality of surface-emitting lasers comprises one or more of a vertical external cavity surface-emitting laser (VECSEL) and vertical-cavity surface-emitting laser (VCSEL).

16. The time-of-flight depth camera of claim 14 , wherein the light guide comprises a wedge-shaped light guide having a total internal reflection surface opposite a light emitting surface, the total internal reflection surface being angled with respect to the light emitting surface.

17. The time-of-flight depth camera of claim 16 , wherein the wedge-shaped light guide is further configured to generate collimated light.

18. The time-of-flight depth camera of claim 14 , wherein the light guide comprises a rectangular-shaped light guide.

19. The time-of-flight depth camera of claim 18 , where the rectangular-shaped 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.

20. The time-of-flight depth camera of claim 14 , wherein the light guide comprises a reflective light guide including a folded light path, the reflective li

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Hudman Joshua Mark
• Masalkar Prafulla

Classifications

• G06T7/521

  from laser ranging, e.g. using interferometry; from the projection of structured light · CPC title

• G01S7/4814 Primary

  of transmitters alone · CPC title

• G01S7/4818

  using optical fibres · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title