As with much concerning the Emperor, very little is known of the droids designated "Opticron". In fact, very few are even aware they exist.
From the exterior, they appear to be standard-issue Imperial probe droids, but further investigation would reveal an amalgamation of technology both exotic and arcane. Much like the Emperor's Hand, these droids are connected through the Force in some way to the mind and will of the Emperor himself. They are his unseen eyes, watching that which he cannot--until he returns from the brink.