Ambient light eye illumination for eye-tracking in near-eye display

An eye-tracking system in a display device, the eye-tracking system comprising:

• an infrared camera;
• a substrate transparent to both visible light and infrared light and configured to be placed in front of an eye of a user of the display device;
• and
• a shortwave-pass filter coupled to a first surface of the substrate, the shortwave-pass filter comprising:
• regions configured to transmit a first portion of visible light and reflect a first portion of infrared light found in ambient light entering the eye tracking system;
• and
• a plurality of windows configured to transmit both a second portion of visible light and a second portion of infrared light, found in the ambient light entering the eye tracking system, to the eye of the user,
• wherein the infrared camera is configured to capture infrared light reflected by the eye of the user.