The slot photoelectric sensor is a slot photoelectric sensor that is a light emitter and a receiver mounted on both sides of a slot face to face. The illuminator can emit infrared light or visible light, and the light receiver can receive light without obstruction. But when the detected object passes through the slot, the light is blocked, the photoelectric switch will act, and output a switch control signal to cut off or turn on the load current, thereby completing a control action. The detection distance of the slot switch is generally only a few centimeters due to the limitation of the overall structure