Pupil detection system

摘要

A pupil detection system projects two small infrared (IR) spots separated by approximately 0.5 mm. Each spot is turned on at different times (or alternatively, they can be modulated at different frequencies). The error signal produced by each spot is compared. If the errors are similar, a pupil is present. If the errors are different, no pupil is present (i.e., a blink or lost tracking). The sequencing of the IR spots and the reading of the detector data occur at the higher rates needed for accurate eye tracking.