This is a photoelectric switch that is composed of 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.