Systems and methods for using a display as an illumination source for eye tracking

A head-mounted display system, comprising:

• a head-mounted display comprising a visible light source including visible light pixels for directing visible images through a visible light waveguide to and centrally in front of the user's eye when in use, wherein the head-mounted display further comprises an infrared light waveguide that is separate from and overlapping the visible light waveguide, wherein the visible light source is edge-mounted relative to the visible light waveguide;
• an infrared source positioned on or in the head-mounted display to project a grid of infrared light from the infrared source through the infrared light waveguide and laterally between the visible light pixels centrally in front of the user's eye and to the user's eye, wherein the infrared source is edge-mounted relative to the infrared light waveguide;
• and
• an infrared sensor for detecting infrared light from the infrared source and reflected from the user's eye and for tracking a position of the user's eye.

A method for eye tracking, comprising:

• directing, with a plurality of visible light pixels of a visible light display comprising a visible light waveguide and a visible light projector edge-mounted to the visible light waveguide, a visible image to an eye of a user;
• directing, with a plurality of infrared pixels positioned to project a grid of infrared light through an infrared light waveguide to the eye of the user laterally between the visible light pixels, wherein the plurality of infrared pixels is produced by an infrared source edge-mounted to the infrared light waveguide and wherein the infrared light waveguide is separate from and overlapping the visible light waveguide;
• and
• detecting, with an infrared sensor, the grid of infrared light originating from the plurality of infrared pixels and reflected from the eye of the user.