EYE TRACKING APPARATUS, METHOD AND SYSTEM

• US 20150185475A1
• Filed: 12/26/2013
• Published: 07/02/2015
• Est. Priority Date: 12/26/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Saarikko, Pasi, McEldowney, Scott, Levola, Tapani, Lou, Xinye, Robbins, Steven
• Granted Patent: US 9,459,451 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: G02B 2027/0107 with optical power
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0093 with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 6/02085 characterised by the grating profile, e.g. chirped, apodised, tilted, helical
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: H04N 13/383 for tracking with gaze detection, i.e. detecting the lines of sight of the viewer's eyes

Abstract

A transparent waveguide for use in eye tracking includes an input-coupler and an output-coupler. The input-coupler comprises a plurality of curved grating lines having a radially varying pitch. When positioned in front of an eye illuminated with infrared light, infrared light beams reflected from the eye and incident on the input-coupler enter the waveguide at the input-coupler, propagate through the waveguide by way of total internal reflections, and exit the waveguide proximate the output-coupler. The radially varying pitch of the curved grating lines of the input-coupler provides angular encoding of infrared light incident on the input-coupler, and more specifically, causes different beams of infrared light incident on respective different horizontal and vertical positions of the input-coupler to propagate through the waveguide at respective different angles of reflection and exit the waveguide at respective different angles of incidence relative to a surface of the waveguide through which infrared light beams exit.

Claims

1. An apparatus for use in tracking an eye that is illuminated by infrared light, the apparatus comprising:

a waveguide that is transparent and includes an input-coupler and an output-coupler;

wherein the input-coupler and the output-coupler are spatially separated from one another;

wherein the input-coupler comprises a plurality of curved grating lines that diffract light beams incident on the input-coupler into the waveguide and towards a common region at which is located the output-coupler by way of total internal reflections;

wherein the plurality of curved grating lines of the input-coupler have a radially varying pitch; and

wherein the plurality of curved grating lines of the input-coupler each have a respective center of curvature and a respective point of convergence that are located within the region of the waveguide at which is located the output-coupler.

2. The apparatus of claim 1, wherein when the input-coupler is positioned in front of an eye that is illuminated with infrared light, infrared light beams reflected from the eye and incident on the input-coupler enter the waveguide at the input-coupler, propagate through the waveguide from the input-coupler to the output-coupler by way of total internal reflections, and exit the waveguide proximate the output-coupler.

3. The apparatus of claim 2, wherein the radially varying pitch of the curved grating lines of the input-coupler causes different infrared light beams that are incident on different horizontal and vertical positions of the input-coupler to propagate through the waveguide at respective different angles of reflection and exit the waveguide at respective different angles of incidence relative to a surface of the waveguide through which the infrared light beams exit.

4. The apparatus of claim 1, wherein the radially varying pitch of the curved grating lines of the input-coupler decreases with increases in distances between the curved grating lines and the output-coupler.

5. The apparatus of claim 1, wherein the input-coupler and the output-coupler are positioned relative to one another to substantially achieve telecentricity.

6. The apparatus of claim 1, wherein the plurality of curved grating lines of the input-coupler are substantially concentric, each have substantially the same center of curvature that is located within the region of the waveguide at which is located the output-coupler, and each have substantially the same point of convergence that is located within the region of the waveguide at which is located the output-coupler.

7. The apparatus of claim 1, wherein the center of curvature and the point of convergence for each of the plurality of curved grating lines of the input-coupler are the same point, which is located at or near a center of the output-coupler.

8. The apparatus of claim 1, wherein an optical transfer function of the input-coupler is substantially equivalent to an optical transfer function of an on-axis holographic lens combined with an optical transfer function of a linear diffraction grating.

10. The apparatus of claim 1, wherein the output-coupler comprises a linear grating, a holographic grating or a prism.

21. The apparatus of claim 1, wherein for each point on each of the plurality of curved grating lines of the input-coupler the respective center of curvature is within the region of the waveguide at which is located the output-coupler.

9. (canceled)

11. A method for use in tracking an eye, the method comprising:

illuminating an eye with infrared light while an input-coupler of a waveguide is generally axially aligned with the eye, which will result in infrared light beams reflected from the eye being incident on the input-coupler of the waveguide;

using curved grating lines of the input-coupler, diffracting the infrared light beams that are incident on the input-coupler of the waveguide towards a common region of the waveguide at which is located an output-coupler; and

using the output-coupler of the waveguide, causing the light beams to exit the waveguide;

wherein the input-coupler and the output-coupler are spatially separated from one another; and

wherein the plurality of curved grating lines of the input-coupler each have a respective center of curvature and a respective point of convergence that are located within the region of the waveguide at which is located the output-coupler.

12. The method of claim 11, further comprising:

causing infrared light beams incident on different portions of the input-coupler to propagate through the waveguide at respective different angles of reflection and exit the waveguide at respective different angles of incidence relative to a surface of the waveguide through which the infrared light beams exit, and thereby causing the infrared light beams traveling through the waveguide and exiting the waveguide to be angularly encoded.

13. The method of claim 12, further comprising:

converting the infrared light beams that exit the waveguide from angularly encoded infrared light beams to two-dimensional spatially encoded infrared light beams.

14. The method of claim 13, further comprising:

generating, in dependence on the two-dimensional spatially encoded infrared light beams, eye tracking data that can be used to track the eye.

15. The method of claim 14, further comprising:

controlling or modifying an aspect of an application based on the eye tracking data.

16. A system for use in tracking an eye, comprising:

an infrared illumination source that produces infrared light that can be used to illuminate an eye;

a waveguide that is transparent and includes an input-coupler and an output-coupler;

wherein the input-coupler and the output-coupler are spatially separated from one another;

wherein the input-coupler of the waveguide comprises a plurality of curved grating lines that diffract infrared light beams incident on the input-coupler into the waveguide and towards a common region at which is located the output-coupler of the waveguide;

wherein the plurality of curved grating lines of the input-coupler have a radially varying pitch that cause infrared light beams incident on different portions of the input-coupler to propagate through the waveguide at respective different angles of reflection and exit the waveguide at respective different angles of incidence relative to a surface of the waveguide through which the infrared light beams exit;

wherein the plurality of curved grating lines of the input-coupler each have a respective center of curvature and a respective point of convergence that are located within the region of the waveguide at which is located the output-coupler; and

wherein when the input-coupler of the waveguide is positioned in front of an eye that is illuminated with infrared light produced by the infrared illumination source, infrared light beams reflected from the eye and incident on the input-coupler enter the waveguide at the input-coupler, propagate through the waveguide from the input-coupler to the output-coupler by way of total internal reflections, and exit the waveguide proximate the output-coupler.

17. The system of claim 16, wherein:

the radially varying pitch of the curved grating lines of the input-coupler decreases with increases in distances between the curved grating lines and the output-coupler; and

for each point on each of the plurality of curved grating lines of the input-coupler the respective center of curvature is within the region of the waveguide at which is located the output-coupler.

18. The system of claim 16, further comprising:

a lens module that converts the infrared light beams that exit the waveguide from angularly encoded infrared light beams to two-dimensional spatially encoded infrared light beams.

19. The system of claim 16, further comprising:

a sensor that produces eye tracking data in dependence on the two-dimensional spatially encoded infrared light beams produced using the lens module.

20. The system of claim 19, further comprising:

a processor that controls or modifies an aspect of an application based on the eye tracking data.