Holographic waveguide optical tracker

Patent metadata

Field	Value
Publication number	US-10423222-B2
Application number	US-201515513288-A
Country	US
Kind code	B2
Filing date	Sep 25, 2015
Priority date	Sep 26, 2014
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

There is provided an object tracker having: a first waveguide; a source of illumination light; a detector optically coupled to the waveguide; and at least one grating lamina formed within the waveguide. Illumination light propagating along a first optical path from the source to an object in relative motion to the object tracker. Image light reflected from at least one surface of an object is deflected by the grating lamina into a second optical path towards the detector.

First claim

The invention claimed is:

1. An object tracker for tracking at least one object using structured light, comprising:
a waveguide;
a source of illumination light optically coupled to said waveguide;
a set of one or more grating lamina elements formed within said waveguide,
wherein said waveguide is configured to direct said illumination light along a first optical path from said source to an object via said set of grating lamina elements, and
wherein said set of grating lamina elements are configured to modify and diffract said illumination light such that said illumination light is modified by said set of grating lamina elements into structured light having a first signal pattern that is characterized by a first speckle pattern diffracted towards said object; and

a detector optically coupled to detect image light reflected from said object, wherein said image light is a reflection of at least a portion said illumination light directed at said object,
wherein said image light is structured light having a second signal pattern that is characterized by a second speckle pattern and is a reflected derivative of said first signal pattern,
wherein said detector is configured to detect said object by detecting the reflected image light and recording said second signal pattern when said waveguide and said detector are in relative motion with said object.

2. The object tracker of claim 1 wherein said first optical path includes a first waveguide path, wherein said reflected image light travels a second optical path that includes a second waveguide path, wherein said set of grating lamina elements is configured to couple said illumination light out of said first waveguide path towards said object, and wherein said set of grating lamina elements is further configured to couple said reflected image light into said second waveguide path towards said detector.

3. The object tracker of claim 2 wherein said set of grating lamina elements includes a first switchable grating element having a diffracting state and a non diffracting state, wherein said first switchable grating element in said diffracting state couples said illumination light in said first waveguide path out of said waveguide towards said object and said first switchable grating element further couples said reflected image light into said second waveguide path towards said detector.

4. The object tracker of claim 2 wherein said set of grating lamina elements includes a first and a second switchable grating element, each having a diffracting state and a non-diffracting state, wherein said first switchable grating element in said diffracting state couples said illumination light in said first waveguide path out of said first waveguide towards said object, and wherein said second switchable grating element in said diffracting state couples said reflected image light into said second waveguide path towards said detector.

5. The object tracker of claim 1 wherein said set of grating lamina elements includes a first switchable grating element having a diffracting state and a non diffracting state.

6. The object tracker of claim 1 wherein said set of grating lamina elements includes at least one grating lamina element selected from the group consisting of: a switchable Bragg grating, a switchable grating recorded in a reverse mode holographic polymer dispersed liquid crystal, a switchable grating recorded in a reverse mode holographic polymer dispersed liquid crystal, a surface relief grating and a non switching Bragg grating.

7. The object tracker of claim 1 wherein said set of grating lamina elements includes at least one pair of grating lamina elements, wherein each orating lamina element of said pair of grating lamina elements is configured to diffract said illumination light into output paths in accordance with a k-vector such the illumination light diffracted by said pair of grating lamina elements each converge towards a center of rotation of said object.

8. The object tracker of claim 1 wherein said set of grating lamina elements includes at least two grating lamina elements, and wherein each grating lamina element of said set of grating lamina elements is configured to diffract said illumination light into parallel output paths.

9. The object tracker of claim 1 wherein said detector is connected to an image processing apparatus for determining at least one spatio-temporal characteristic of an object movement.

10. The object tracker of claim 1 further comprising an image processing system which includes at least one of an edge finding algorithm, a centroid detection algorithm or a neural network.

11. The object tracker of claim 1 wherein the waveguide and detector are implemented in a device selected from the group consisting of: an eye tracker, a LIDAR, an eye-slaved display, a display implementing foveated rendering, and a display using gaze vector data to adjust a displayed image to provide vergence accommodation related depth cues.

12. The object tracker of claim 1 wherein said set of grating lamina elements is configured to diffract said illumination light into multiple illumination perspectives such that reflected high signal to noise ratio throughout the field of view.

13. The object tracker of claim 1 wherein said detector is a fast low resolution detector.

14. The object tracker of claim 1 wherein signal of said first and said second signal pattern is further characterized by at least one of: beam intensity profile, phase distribution, or beam direction.

15. The object tracker of claim 1 further comprising a lens that focuses said image light onto said detector.

16. The object tracker of claim 1 wherein said detector is configured to detect said object when said object is fixed in a three dimensional space and said waveguide or said detector are in motion relative to said object.

17. The object tracker of claim 1 wherein said detector is configured to detect said object when said waveguide or said detector move along a curvilinear path in three dimensional space.

18. The object tracker of claim 1 wherein said set of grating lamina elements include a first and a second grating lamina element, wherein said first grating lamina element is configured to diverge said illumination light into a first beam divergence width, and wherein said second grating lamina element is configured to diverge said illumination light into a second beam divergence width, and wherein said first and said second beam divergence widths are different.

19. The object tracker of claim 1 wherein said set of grating lamina elements include a first and a second grating lamina element, wherein said first grating lamina element is configured to modify said illumination light into a first speckle contrast, and wherein said second grating lamina element is configured to modify said illumination light into a second speckle contrast, wherein said first and said second speckle contrasts are different, and wherein said first speckle pattern is characterized by at least said first and said second speckle contrasts.

20. The object tracker of claim 1 wherein said set of grating lamina elements include a first and a second grating lamina element, wherein said orating lamina first element is configured to modify said illumination light into a first speckle grain size, and wherein said second grating lamina element is configured to modify said illumination light into a second speckle grain size, wherein said first and said second speckle grain sizes are different, and wherein said first speckle patter

Assignees

• Digilens Inc

Inventors

• Popovich Milan Momcilo
• Waldern Jonathan David
• Grant Alastair John
• Lokovic Kimberly Sun

Classifications

• G02F2201/307

  Reflective grating, i.e. Bragg grating · CPC title

• G02B6/0016

  Grooves, prisms, gratings, scattering particles or rough surfaces · CPC title

• G02F1/2955

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical waveguide switching G02F1/313) · CPC title

• A61B3/113

  for determining or recording eye movement · CPC title

• G02B27/017

  Head mounted · CPC title