Sub-resolution optical detection

Patent metadata

Field	Value
Publication number	US-9523771-B2
Application number	US-201514595369-A
Country	US
Kind code	B2
Filing date	Jan 13, 2015
Priority date	Jan 13, 2014
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A detector for optical detection of location within a volume, comprises a beam source for shining a structured light pattern on the volume and a digital detector having detection pixels of a given size. The light pattern, when shone into the volume and reflected back to the detection pixels, has a brightness distribution with a peak and a surrounding brightness structure. Now often the peak may be smaller than the pixel size although the overall distribution of the brightness extends over multiple pixels. The system includes an electronic processor for assessing a distribution of brightness among the neighboring pixels to infer a location of the peak within a region smaller than the size of the central pixel on which it falls, thus giving sub-pixel resolution.

First claim

What is claimed is:

1. An apparatus, comprising:
a structured light source for projecting a structured light pattern into a volume;
a digital detector having a plurality of detection pixels configured to receive the structured light pattern reflected from the volume; and
an electronic processor coupled to the digital detector configured to receive pixel values indicating a light intensity signal related to the structured light pattern reflected from the volume, the light intensity signal includes a peak and a surrounding structure, wherein the electronic processor is further configured to
analyze, across a subset of the detection pixels having the pixel values, a distribution of the peak and the surrounding structure, and
determine, based on the analysis, a location of the peak within a region smaller than a size of a detection pixel of the plurality of detection pixels.

2. The apparatus of claim 1 , wherein the distribution indicates brightness of the received structured light pattern reflected from the volume across the subset of the detection pixels.

3. The apparatus of claim 1 , further comprising a diffraction element located in front of the plurality of detection pixels.

4. The apparatus of claim 3 , wherein the diffraction element is configured to convert, at the digital detector, the structured light pattern reflected from the volume into the pixel values indicating the light intensity signal having an undiverted main peak and at least one auxiliary peak in the surrounding structure across the subset of the detection pixels, and wherein the electronic processor is further configured to infer the location of the peak within the region based on the main peak and the at least one auxiliary peak.

5. The apparatus of claim 4 , wherein the diffraction element is configured to place the at least one auxiliary peak in a vicinity of a detection pixel in the subset of the detection pixels detecting the main peak.

6. The apparatus of claim 2 , wherein each detection pixel of the plurality of detection pixels is divided into a plurality of zones, and wherein the processor is configured to map combinations of levels of the brightness across the subset of the detection pixels to one of the zones on a detection pixel in the subset of the detection pixels.

7. The apparatus of claim 6 , wherein the combinations of levels of the brightness comprise levels of brightness in two spatial dimensions across the subset of the detection pixels.

8. The apparatus of claim 6 , wherein the plurality of zones comprises at least five zones per detection pixel.

9. The apparatus of claim 4 , wherein the diffraction element is configured such that each of the at least one auxiliary peak is located at a boundary between two or more detection pixels in the subset of the detection pixels when the undiverted main peak is located at a center of a first detection pixel in the subset of the detection pixels.

10. The apparatus of claim 1 , further comprising a diffraction element located on an outward beam path of the structured light pattern from the structured light source into the volume.

11. The apparatus of claim 1 , further comprising a distortion element located in front of the plurality of detection pixels, wherein the distortion element is configured to distort the structured light pattern reflected from the volume producing distorted brightness distribution over a central detection pixel and neighboring pixels of the subset of the detection pixels, and wherein the electronic processor is further configured to infer the location of the peak based on the distorted brightness distribution.

12. The apparatus of claim 11 , wherein each detection pixel of the plurality of detection pixels is divided into a plurality of zones, and wherein the processor is further configured to map combinations of levels of the distorted brightness distribution across the subset of the detection pixels to one of the zones on a detection pixel in the subset of the detection pixels.

13. The apparatus of claim 3 , wherein the diffraction element is located on a lens in front of the digital detector.

14. A method, comprising:
projecting a structured light pattern into a volume;
receiving, at a plurality of detection pixels, the structured light pattern reflected from the volume;
receiving pixel values indicating a light intensity signal related to the structured light pattern reflected from the volume, the light intensity signal includes a peak and a surrounding structure;
analyzing, across a subset of the detection pixels having the pixel values, a distribution of the peak and the surrounding structure; and
determining, based on the analysis, a location of the peak within a region smaller than a size of a detection pixel of the plurality of detection pixels.

15. The method of claim 14 , wherein the distribution indicates brightness of the received structured light pattern reflected from the volume across the subset of the detection pixels.

16. The method of claim 14 , further comprising:
converting the structured light pattern reflected from the volume into the pixel values indicating the light intensity signal having an undiverted main peak and at least one auxiliary peak at one or more detection pixels in the subset adjacent to a detection pixel in the subset detecting the main peak; and wherein
determining the location of the peak comprises inferring the location of the peak within the region based on the main peak and the at least one auxiliary peak.

17. The method of claim 15 , wherein each detection pixel of the plurality of detection pixels is divided into a plurality of zones, and wherein determining the location of the peak comprises mapping combinations of levels of the brightness across the subset of the detection pixels to one of the zones on a detection pixel in the subset of the detection pixels.

18. The method of claim 17 , further comprising performing the mapping in two spatial dimensions across the subset of the detection pixels.

19. The method of claim 17 , wherein the plurality of zones comprises at least ten zones per detection pixel.

20. The method of claim 16 , wherein converting comprises applying an optical function designed to ensure that each of the at least one auxiliary peak is located at a boundary between two or more detection pixels in the subset of the detection pixels when the undiverted main peak is located at a center of a first detection pixel in the subset of the detection pixels.

21. The method of claim 14 , further comprising collimating beams of the structured light pattern when projecting the structured light pattern into the volume.

22. The method of claim 14 , further comprising distorting the structured light pattern reflected from the volume producing distorted brightness distribution over a central detection pixel and neighboring pixels of the subset of the detection pixels, and wherein determining the location of the peak comprises inferring the location of the peak based on the distorted brightness distribution.

23. The method of claim 22 , wherein each detection pixel of the plurality of detection pixels is divided into a plurality of zones, and wherein determining the location of the peak comprises mapping combinations of levels of the distorted brightness distribution across the subset of the detection pixels to one of the zones on a detection pixel in the subset of the detection pixels.

24. The method of claim 14 , wherein beams of the

Assignees

• Oculus Vr Llc
• Facebook Inc

Inventors

• Romano Nitay
• Grossinger Nadav
• Alon Emil
• Alpern Yair

Classifications

• G06F3/017

  Gesture based interaction, e.g. based on a set of recognized hand gestures (interaction based on gestures traced on a digitiser G06F3/04883) · CPC title

• G01B11/25

  by projecting a pattern, e.g. {one or more lines,} moiré fringes on the object (G01B11/255 takes precedence {; image analysis for depth or shape recovery G06T7/50}) · CPC title

• G01S17/48

  Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves · CPC title

• G06F3/0304

  Detection arrangements using opto-electronic means (constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042) · CPC title

• G01S17/06 Primary

  Systems determining position data of a target · CPC title