This is a photoelectric switch that is composed of an emitter and receptor. The emitter consists of a laser diode, and the laser has the characteristics of high precision, good orientation etc. The receptor consists of a photoelectric element. When receiving the laser pulse, the built-in light-conducting. The emitter and receptor can assemble a detector. It can be directly compatible with Arduino to develop related products. Of course,it is also very suitable for photoelectric counting, security, ultra-high vehicle overrun detection etc.