OPTICAL SYSTEMS AND METHODS FOR EYE TRACKING BASED ON EYE IMAGING VIA COLLIMATING ELEMENT AND LIGHT-GUIDE OPTICAL ELEMENT

A light-transmitting substrate is deployed with a first of two major surfaces in facing relation to an eye of a viewer and guides light by internal reflection between the two major surfaces. An optical coupling-out configuration couples image light, that corresponds to a collimated image and that is guided by internal reflection between the two major surfaces, out of the light-transmitting substrate. A first optical coupling configuration collimates light from the eye to produce collimated light, and couples the collimated light into the light-transmitting substrate for guiding by internal reflection. A second optical coupling configuration couples the collimated light out of the light-transmitting substrate toward an optical sensor that senses the coupled-out light. A processing system derives current gaze direction of the eye by processing signals from the optical sensor.