Classification of optocouplers by design
Optocoupler & dash; optocoupler in a closed (usually sealed) case. It serves to transmit signals and galvanic isolation of chains.
Slit optocoupler is designed commonly to track mechanical movement. A piece of opaque material, special encoder wheel or other object is placed in the gap between the transmitter and receiver, affecting the passage of radiation.
Classification of optocouplers by sensing element
Resistor
Diode
Transistor
Thyristor