*3.1. Image Acquisition Frame Design*

The concept of the design for an eye-frame was first visualized using Fusion 360 software to validate its user friendliness. Two infrared (IR) [41] cameras were mounted on small platforms supported by flexible arms below eye level. Flexible arms were used to allow position adjustment of the two cameras for different users. The cameras were positioned at a distance that allowed the full eye movement range to be recorded, as seen in Figure 5. The reason for using the IR cameras was primary because (i) the acquired images were almost the same under different lighting conditions and (ii) the user was not irritated by the light emitted from the IR LEDs.

**Figure 5.** Image acquisition system using IR camera.
