Optical modules that reduce speckle contrast and diffraction artifacts

• US 9,462,253 B2
• Filed: 09/23/2013
• Issued: 10/04/2016
• Est. Priority Date: 09/23/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Hudman, Joshua, DePue, Marshall
• Primary Examiner(s): Patel, Jay Au
• Assistant Examiner(s): HUANG, FRANK F
• Application Number:
  US14/034,189
• Publication Number:
  US 20150085075A1
• Time in Patent Office: 1,107 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: H04N 13/128 Adjusting depth or disparity
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/229 using lenticular lenses, e.g. arrangements of cylindrical lenses
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An optical module, for use in a depth camera, includes a plurality of laser emitting elements, each of which emits a corresponding laser beam, and a micro-lens array (MLA) that includes a plurality of lenslets. Laser beams emitted by adjacent laser emitting elements at least partially overlap one another prior to being incident on the MLA For each lenslet of at least a majority of the lenslets of the MLA, the lenslet is at least partially filled by light corresponding to laser beams emitted by at least two of the laser emitting elements. The inclusion of the plurality of laser emitting elements is used to reduce speckle contrast. The overlap of the laser beams, and the at least partially filling of the lenslets of the MLA with light corresponding to laser beams emitted by multiple laser emitting elements, is used to reduce diffraction artifacts.

Claims

1. A depth camera system for use in obtaining a depth image of a capture area, comprising:

an optical module configured to output infrared (IR) light that illuminates the capture area;

an image pixel detector array configured to detect a portion of the IR light, output by the optical module, that has reflected off one or more objects within the capture area and is incident on the image pixel detector array; and

a processor configured to produce the depth image based on the portion of the IR light detected by the image pixel detector;

wherein the optical module includes

a plurality of laser emitting elements each of which is operable to emit a corresponding IR laser beam, the plurality of laser emitting elements including five or more laser emitting elements; and

a micro-lens array including a two-dimensional array of substantially identical lenslets;

wherein adjacent ones of the laser emitting elements are configured to emit IR laser beams that at least partially overlap one another prior to being incident on the micro-lens array;

wherein for each lenslet of at least a majority of the lenslets in the two-dimensional array of substantially identical lenslets of the micro-lens array, the lenslet is configured to be at least partially filled by IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements;

wherein a number of lenlests, in the two-dimensional array of substantially identical lenslets of the micro-lens array, is greater than a number of laser emitting elements;

wherein a center-to-center distance between any two of the light emitting elements that are adjacent to one another is less than 100 μ

m; and

wherein a center-to-center distance between any two of the light emitting elements that are not adjacent to one another is less than 1 mm.

2. The depth camera system of claim 1, wherein IR light exiting the micro-lens array comprises the IR light output by the optical module that illuminates the capture area.

3. The depth camera system of claim 1, wherein:

the inclusion of the plurality of laser emitting elements in the optical module reduces speckle contrast in the IR light that is output by the optical module and illuminates the capture area; and

the overlap of the IR laser beams emitted by adjacent ones of the laser emitting elements, and the at least partially filling of the lenslets of the micro-lens array with IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements, reduces diffraction pattern artifacts in the IR light that is output by the optical module and illuminates the capture area.

4. The depth camera system of claim 1, wherein each of the laser emitting elements is configured to emit highly IR coherent light.

5. The depth camera system of claim 1, wherein for each lenslet of the at least a majority of the lenslets of the micro-lens array, the lenslet is configured to be completely filled by IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements.

6. The depth camera system of claim 1, wherein:

the plurality of laser emitting elements comprise five or more edge emitting lasers.

7. The depth camera system of claim 6, wherein the five or more edge emitting lasers comprise five or more parallel laser stripes fabricated on a same semiconductor substrate.

8. The depth camera system of claim 1, wherein:

the plurality of laser emitting elements comprises an array of five or more vertical-cavity surface-emitting lasers (VCSELs).

9. The depth camera system of claim 1, wherein the micro-lens array is a periodic structure.

19. The depth camera system of claim 1, wherein:

the two-dimensional array of substantially identical lenslets of the micro-lens array of the optical module comprises at least a 7×

7 array of the substantially identical lenslets; and

for each lenslet of at least a majority of the lenslets, in the at least 7×

7 array of the substantially identical lenslets, the lenslet is configured to be at least partially filled by IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements.

10. A method for use by a depth camera, the method comprising:

outputting infrared (IR) light from an optical module of the depth camera to thereby illuminate a capture area with the IR light;

detecting a portion of the IR light that has reflected off one or more objects within the capture area;

producing a depth image based on the detected portion of the IR light; and

updating an application based on the depth image;

wherein the outputting IR light from the optical module includes emitting a plurality of separate IR laser beams towards a micro-lens array that includes a two-dimensional array of lenslets such that

adjacent IR laser beams at least partially overlap one another prior to being incident on the micro-lens array, and

for each lenslet of at least a majority of the lenslets in the two-dimensional array of lenslets of the micro-lens array, the lenslet is at least partially filled by IR light corresponding to at least five of the IR laser beams.

11. The method of claim 10, wherein the emitting the plurality of separate IR laser beams towards the micro-lens array that includes the plurality of lenslets is performed such that each of the IR laser beams at least partially overlaps each of the other IR laser beams of the plurality of separate IR laser beams, prior to the plurality of IR laser beams being incident on the micro-lens array.

12. The method of claim 10, wherein the emitting the plurality of separate IR laser beams towards the micro-lens array that includes the plurality of lenslets is performed such that each lenslet of the micro-lens array, is at least partially filled by each IR laser beam of the plurality of IR laser beams.

13. The method of claim 10, wherein the emitting the plurality of separate IR laser beams towards the micro-lens array that includes the plurality of lenslets is performed such that each lenslet of the at least a majority of the lenslets of the micro-lens array, is completely filled by at least five IR laser beams.

14. An optical module for use with a depth camera system for use in obtaining a depth image of a capture area, the optical module comprising:

a plurality of laser emitting elements each of which is configured to emit a corresponding infrared (IR) laser beam; and

a micro-lens array including a two-dimensional array of lenslets;

wherein IR laser beams emitted by adjacent ones of the laser emitting elements at least partially overlap one another prior to being incident on the micro-lens array;

wherein for each lenslet of at least a majority of the lenslets in the two-dimensional array of lenslets of the micro-lens array, the lenslet is configured to be at least partially filled by IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements and

wherein a number of lenlests, in the two-dimensional array of substantially identical lenslets of the micro-lens array, is greater than a number of laser emitting elements.

15. The optical module of claim 14, wherein for each lenslet of the at least a majority of the lenslets of the micro-lens array, the lenslet is configured to be at least partially filled by IR light corresponding to IR laser beams emitted by at least five of the laser emitting elements.

16. The optical module of claim 14, wherein for each lenslet of the at least a majority of the lenslets of the micro-lens array, the lenslet is configured to be completely filled by IR light corresponding to IR laser beams emitted by at least five of laser emitting elements.

17. The optical module of claim 14, wherein the plurality of laser emitting elements comprise five or more edge emitting lasers.

18. The optical module of claim 14, wherein the plurality of laser emitting elements comprises an array of vertical-cavity surface-emitting lasers (VCSELs).