Optical mice use two optical assemblies, each composed of an |LED| and a ~phototransistor~. The LED is positioned on one side of the synchronizer wheel and shines through notches or holes in it. As the wheel turns, the notches allow the light to flash through. The phototransistor is positioned on the other side of the wheel to detects the light pulses. The phototransistor translates these pulses into electrical signals. The computer then processes these to determine the directional components of the tracking ball's motion.
