INTERFERENCE PATTERN DETECTION FOR EYE TRACKING IN A HEAD-MOUNTED DEVICE

An eye tracking system for a head-mounted devices includes an interference pattern emitter, an interference pattern detector, and processing logic. The interference pattern emitter provides at least two light beams that combine into a light pattern in an eyebox region of the head-mounted device. The light pattern includes an interference pattern based on constructive and destructive interference of the at least two light beams. The light detector is configured to detect a portion of the light pattern and provides detector data that is representative of one or more light intensities in the portion of the light pattern. The processing logic is coupled to the light detector to receive the detector data and is configured to identify displacement characteristics of the interference pattern. The processing logic is configured to determine orientation characteristics of an eye in the eyebox region based on the displacement characteristics.