- "Either something is wrong with my photoreceptors…or a ship is touching down over there."
Photoreceptors, also known as visual sensors, was a technical name for the optical sensors of a droid. They were the equivalent to an eye. Numbers of photoreceptors could vary depending on the size and model of a droid. For instance, R2-D2 had one, while EV-9D9 had three. Many droids, like C-3PO, had two. Some could have them in different areas. For instance, General Grievous' MagnaGuards had a built-in one in their torso to enable them to fight without their heads.[source?]