In-field illumination for eye tracking

An eye-tracking unit for a near-eye display device, the eye-tracking unit comprising:

• a substrate transparent to visible light and configured to be placed in front of an eye of a user;
• a plurality of light sources positioned sparsely in or on a surface of the substrate and configured to emit infrared light for eye tracking;
• a plurality of beam diverting components that are spaced apart from each other and are placed sparsely on the substrate or the plurality of light sources in a field of view of the eye of the user, wherein each beam diverting component of the plurality of beam diverting components corresponds to one respective light source of the plurality of light sources, and is configured to direct the infrared light from the respective light source of the plurality of light sources to a different respective direction toward the eye of the user;
• and
• a camera configured to receive the infrared light from the plurality of light sources that is reflected by the eye of the user,
• wherein, for each light source of the plurality of light sources:
• the light source is configured to be positioned within the field of view of the eye of the user, and
• a maximum dimension of the light source in a plane parallel to an emission surface of the light source is less than 500 μm.

A method of tracking an eye of a user of a near-eye display, the method comprising:

• emitting infrared light by a plurality of light sources positioned sparsely on a transparent substrate within a field of view of the eye of the user, wherein, for each light source of the plurality of light sources, a maximum dimension of the light source in a plane parallel to an emission surface of the light source is less than 500 μm;
• directing, by each beam diverting component of a plurality of beam diverting components that are spaced apart from each other and are placed sparsely on the transparent substrate or the plurality of light sources in a field of view of the eye of the user, the infrared light from a respective light source of the plurality of light sources to a different respective direction toward the eye of the user, wherein each beam diverting component of the plurality of beam diverting components corresponds to one light source of the plurality of light sources;
• and
• receiving, by a camera, the infrared light from the plurality of light sources and reflected by the eye of the user.