Eye tracking apparatus, method and system
First Claim
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;
a light source adapted to illuminate an eye with infrared light so that at least a portion of the infrared light is reflected from the eye and is incident on the input-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 are configured to diffract infrared 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 that decreases with increases in distances between the curved grating lines and the output-coupler;
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 the input-coupler is configured to work as a focus element so that when the input-coupler is at a nominal eye relief distance, which is a focal distance of the input-coupler, ray bundles of infrared light reflected from a same field point on the eye that enter the waveguide through the input-coupler become collimated inside of the waveguide and exit the waveguide with a same angle of incidence relative to a surface of the waveguide through which the infrared light exits, and ray bundles of the infrared light reflected from different field points on the eye propagate through the waveguide at respective different angles of reflection and exit the waveguide with respective different angles of incidence relative to the surface of the waveguide through which the infrared light exits, which thereby provides for angular encoding of infrared light that is reflected off different field points on the eye.
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Accused Products
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.
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Citations
19 Claims
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1. An apparatus for use in tracking an eye that is illuminated by infrared light, the apparatus comprising:
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a waveguide that is transparent and includes an input-coupler and an output-coupler; a light source adapted to illuminate an eye with infrared light so that at least a portion of the infrared light is reflected from the eye and is incident on the input-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 are configured to diffract infrared 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 that decreases with increases in distances between the curved grating lines and the output-coupler; 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 the input-coupler is configured to work as a focus element so that when the input-coupler is at a nominal eye relief distance, which is a focal distance of the input-coupler, ray bundles of infrared light reflected from a same field point on the eye that enter the waveguide through the input-coupler become collimated inside of the waveguide and exit the waveguide with a same angle of incidence relative to a surface of the waveguide through which the infrared light exits, and ray bundles of the infrared light reflected from different field points on the eye propagate through the waveguide at respective different angles of reflection and exit the waveguide with respective different angles of incidence relative to the surface of the waveguide through which the infrared light exits, which thereby provides for angular encoding of infrared light that is reflected off different field points on the eye. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for use in tracking an eye, the method comprising:
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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, the eye at a nominal eye relief distance, which is a focal distance of the input-coupler; 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; using the output-coupler of the waveguide, causing the light beams to exit the waveguide; angularly encoding infrared light that is reflected from the eye by causing ray bundles of infrared light reflected from a same field point on the eye that enter the waveguide through the input-coupler to become collimated inside of the waveguide and exit the waveguide with a same angle of incidence relative to a surface of the waveguide through which the infrared light exits, and causing ray bundles of the infrared light reflected from different field points on the eye to propagate through the waveguide at respective different angles of reflection and exit the waveguide with respective different angles of incidence relative to the surface of the waveguide through which the infrared light exits; and 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. - View Dependent Claims (12, 13, 14)
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15. A system for use in tracking an eye, comprising:
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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 and are configured to cause the input-coupler to work as a focus element so that ray bundles of infrared light reflected from a same field point on the eye that enter the waveguide through the input-coupler become collimated inside of the waveguide and exit the waveguide with a same angle of incidence relative to a surface of the waveguide through which the infrared light exits, and ray bundles of the infrared light reflected from different field points on the eye propagate through the waveguide at respective different angles of reflection and exit the waveguide at respective different angles of incidence relative to the 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. - View Dependent Claims (16, 17, 18, 19)
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Specification