Photoreceptors was a generic name for the optical sensors of a droid. They are the equivalent to a droid's eyes. Numbers of photoreceptors can vary, depending on the size and model of a droid. For instance, R2-D2 has one and Jabba's droid, EV-9D9 has three. Most droids, like C3-PO have 2. Some can have them in different areas. For instance, General Grievous' magnaguards have a built-in one in their torso to enable them to fight without their heads.
- Star Wars Rebels: The Visual Guide
- Star Wars: The Force Awakens: The Visual Dictionary
- Ghosts of Dathomir
- Star Wars: The Last Jedi: The Visual Dictionary
- Star Wars Encyclopedia of Starfighters and Other Vehicles
- Star Wars: The Complete Visual Dictionary, New Edition
- Star Wars: Droidography