The present disclosure generally relates to an eye tracker, and specifically relates to an eye tracker that can be embedded in a frame of a compact augmented reality (AR) display.
Head mounted devices (HMD) for virtual reality (VR) systems typically have a mirror arranged in between a lens and a display. The mirror directs light reflected from the eye to a camera that is used for eye tracking. Because virtual reality systems have relatively large form factors, and have room between the lens and the display, the mirror can be positioned behind the lens.
Augmented reality systems typically rely on wearable devices that have much smaller form factors than classical VR head mounted devices. For example, augmented reality devices may be near-eye-displays that resemble eyeglasses. In such devices, a mirror cannot be conveniently placed behind a lens. Instead, augmented reality devices often include a camera that images the eye directly. However, to avoid disrupting the view of the user, the camera is typically placed far from the optical axis, e.g., in the frame of the device. This results in a very off-axis view, which hinders accurate tracking of the eye. Furthermore, the camera is exposed, and can easily become dirty, scratched, or damaged.