The photoelectric sensor is a kind of sensor, which converts the intensity changes of light between the transmitter and the receiver to the change of current to achieve the purpose of testing. Because the output and input circuits of the photoelectric sensor are electrically isolated (that is, electrical insulation), it can be used in many occasions. A new generation of  photoelectric sensor devices fabricated with the adoption of integrated circuit technology and SMT surface mounting technology, has intelligent functions such as retardation, broadening, external synchronization, anti-interference, high reliability, stable working area and self-diagnosis, This novel photoelectric sensor is an active photoelectric testing system electronic sensor with pulse modulation. The cold light source it uses has infrared light, red light, green light, blue light, etc. It can be used to quickly control the state and movement of various substances such as solid, liquid, transparent body, black body, soft body and smoke without contact and harm. It carries merits of small volume, multiple functions, long life, high precision, high response speed, long testing distance and strong ability to resist light, electricity and magnetic interference.