Infrared photoelectric sensor:

       Application is earlier of this sensor which adopted infrared modulating optical pulse emission, so has the high sensitivity, nearly can detected all objects include transparent film.  
DS50E3  Photoelectric sensor                                                                                                YD-N-18 Photoelectric sensor

CH2-N-20 infrared photoelectric sensor
       A model for the CH2-N-20,This sensor has two infrared transmit and receive light path, the distance of them is 0.5~1mm. Because it free from quivering, light intensity is steady, combining with special control method, so has higher control accuracy. Also has stable effect when control transparent film if adjustment emitted light intensity and receiving sensitivity rightly.