Photoelectric proximity sensor

There are three types of photoelectric sensors available. The Direct Reflection (Diffused), emitter and receiver are housed together and use the light reflected directly off the object for detection. In the Reflection with Reflector (Retro-reflective) version, the emitter and receiver are housed together and require a reflector. An object is detected when it interrupts the light beam between the sensor and reflector. With the Thru Beam version, the emitter and receiver are housed separately and detect an object when it interrupts the light beam between the emitter and receiver.