The TCUT1630X01 is part of the optical sensor product portfolio by Vishay. The infrared emitter and phototransistor(s) face each other in this unique slotted interrupter. The sensor works by allowing light to reach the phototransistor(s) if there is not object to detected and there is a signal or output current. If there is an object to detect, the light is blocked, and there is no signal on the output. This sensor is unique due to the included third transistor making it a 3-channel slotted interrupter. This additional transistor adds a channel for a vertical "push" function or an indexing "turn" tab on the code wheel.