In the 1950s the company started producing optical encoders.
This was the first modern computer mouse using an optical encoder.
Modern servomotors use optical encoders, either absolute or incremental.
When the machine axis moves, the dark marks move under the optical encoders triggering them in succession.
Incremental optical encoders then track along with the motors to check for errors.
The mouse contained only electromechanical components: a button, and two optical encoders.
The same type optical encoders are used.
It also has an optical encoder which detects forward and reverse pedal motion.
One development of the optical encoder employs two photosensitive devices with a small relative displacement.
They were positioned by a voice coil actuator using a linear optical encoder for feedback.