Basic Operation of Optical Rotary Incremental Encoders

Optical rotary incremental encoders consist of five main components: LED light source, Rotating code disk, Stationary mask, Photodetector(s), Amplifying/squaring electronics. As the code disk rotates in front of the stationary mask, it shutters light from the LED. The light that passes through the mask is received by the photodetector, which produces pulses in the form of a quasi-sine wave. The encoder electronics convert the sine wave into a square signal, ready for transmission to a counter.