KJT laser sensor (laser photoelectric switch) is a sensor that uses laser technology for measurement. It consists of laser, laser detector and measurement circuit. Laser sensor is a new type of measuring instrument. Its advantages are that it can achieve non-contact long-distance measurement, fast speed, high precision, large measuring range, and strong resistance to light and electrical interference. The angle of laser beam emission is small, the beam is concentrated and the unit beam energy is strong. The power density of the laser beam received by the target is several times that of the infrared light-emitting diode beam. Therefore, it has strong ability to penetrate rain, snow, fog, and wind and sand, greatly reducing false alarms. High efficiency and can be used in situations where other technologies cannot be applied.