Designing an eye tracker involves choosing the most appropriate hardware components. A variety of hardware components are available for building an eye tracker, but it is not obvious which ones are the most appropriate. Common factors to consider are:
• Sensitivity to low light conditions
• Camera speed
• Camera fidelity
• Weight
• The working distance of the user
• Light emission levels (for safety)
• Costs
Manufacturers of commercial eye trackers do not provide detailed information about their hardware, but their choices most likely aim to optimise certain (perhaps unknown) goals. High accuracy under head movement conditions and minimisation of user calibration are usually optimised. By contrast, researchers exploring low-cost eye tracking solutions publish their hardware selection (Fritzer, Droege, & Paulus, 2005; Hansen & Pece, 2005; Hansen, San Agustin, & Villanueva, 2010; San Augustin et al., 2010; Winfield, Li, Babcock, & Parkhurst, 2005). However, these systems often have different parameters to optimise – for example, being designed for minimal price and increased flexibility. Each system has its hardware design choices that influence the usability and price of the system. This chapter discusses the hardware components used in most eye trackers. It is our hope that the overview provides sufficient understanding of the hardware components that it could be used to make your own eye tracker.