Safety issues and infrared light

Infrared light is the most common choice for illumination of the eye in current eye trackers, usually produced via IR light-emitting diodes (LEDs). This chapter provides an overview of the potential hazards of over-exposure to infrared light, the safety standards currently in place, configurations and lighting conditions employed by various eye tracking systems, the basics of measurement of IR light sources in eye trackers, and special considerations associated with continuous exposure in the case of gaze control for communication and disabled users. It should be emphasised that any eye tracker intended for production should undergo testing by qualified professionals at a recognised test house, in a controlled laboratory setting. However, some knowledge of the measurement procedures and issues involved should be useful to designers and users of eye tracking systems.