Toward Micro Eye Movement Detection in Practice: Stand-alone Eye Tracker with High Resolution and Wide Measurement Range

Detecting the micromovements of eyes that reflect a person’s inner state can be an essential step in many applications, but most eye trackers need to fix the subject’s head using a chin rest to obtain sufficient data quality. We propose a stand-alone eye tracker that utilizes two 500 fps cameras, a pair of rotating mirrors for gaze control, a liquid lens for focus control and an intensity-controllable light source, and describe how the proposed system works in real-time. The experimental results show that our system covers more than twice as wide a measurement range in the depth direction as the conventional eye tracker while achieving sufficient data quality to analyze microsaccades with an amplitude of down to 0.2 deg. We also examine the practical use of the proposed system for microsaccade detection.