Eye tracking using light guide with faceted combiner

An eye tracking system comprising:

• a light guide configured to be disposed between a user eye and a display, the light guide comprising a transparent body having:
• a first surface, a second surface opposite the first surface, and a third surface between the first surface and the second surface;
• the first surface composed of a substantially planar surface;
• and
• the second surface comprising a combiner region having a plurality of facets arranged along a plane having a non-zero angle relative to the first surface and configured to reflect light incident on a corresponding region of the first surface internally through the body toward the third surface.

A system comprising:

• a light guide having a body, a first surface oriented toward a user, a second surface oriented away from the user, a collecting facet at a third surface of the light guide, and a plurality of facets formed in the second surface over a combiner area, each facet having a facet surface and a facet pitch angle, each of the facets reflecting a portion of infra-red (IR) light incident on a user eye into the body of the light guide and toward the third surface of the light guide;
• a first light-reflecting material placed proximate to the combiner area of the second surface of the light guide, the first light-reflecting material to reflect infra-red (IR) light from the user eye toward the third surface along the body of the light guide toward the collecting facet, and the first light-reflecting material allowing at least a portion of visible light to pass through the first light-reflecting material;
• an image sensor oriented toward the collecting facet of the light guide;
• a processor coupled to the image sensor;
• and
• a storage component, coupled to the processor, to store executable instructions, the executable instructions including:
• instructions to manipulate the processor to capture an image of the user eye via the collecting facet of the light guide;
• and
• instructions to manipulate the processor to locate an element of the user eye in the image.

In a near-eye display system, a method comprising:

• providing a light guide disposed between a first user eye and a display of the near-eye display system, the light guide comprising a body, a first surface disposed toward the first user eye, a second surface having a first plurality of facets, each facet oriented at a respective pitch angle thereby reflecting light internally into the body of the light guide and toward a third surface disposed between the first surface and the second surface;
• capturing, via an imaging sensor facing the third surface of the light guide, an image of the first eye from light reflected from the first eye and incident on the first surface of the light guide;
• and
• determining a pose of the first user eye based at least in part on the captured image of the first eye.