Do I need a Reflector for my Photoelectric Sensor

We are often asked whether or not a particular sensor such as the DX80N9Q45LP from Banner Engineering Corporation need a reflector to operate.

Photoelectric sensors use light to detect the presence or absence of an object within the sensor’s field of view. Whether or not your sensor needs a reflector to operate depends on which type of sensor you are looking at purchasing.

There are three main types of photoelectric sensors:

Through-Beam Sensors: Through-beam sensors use a separate emitter and receiver. The emitter releases a beam of light that travels straight to the receiver, typically creating a normally closed circuit. If the beam of light is blocked by an object the circuit switches to an open circuit. The through-beam sensors can detect objects over long distances but require careful placement and alignment to ensure proper operation. Clear objects may not be detected by this type of sensor.

Retroreflective Sensors: Similar to the through-beam sensors these sensors use an emitter and a receiver to send and detect a beam of light, however both the emitter and receiver are contained within the same unit. For proper detection of objects retroreflective sensors require a reflector be mounted directly across from the sensor. Like through-beam sensors these are typically normally closed circuits and switch to normally open circuits when an object is detected. Retroreflective sensors have a shorter range than through-beam sensors and may not detect shiny objects because they reflect the light back similar to the way the reflector does.

Diffused Sensors: Similar to retroreflective sensors the emitter and receiver in a diffused sensor are housed within the same unit. However, rather than relying on a reflector to bounce the light back to the sensor it instead uses the object itself. Their circuit typically behaves the same as the other two types of sensors. Because it uses the object to return the light, diffused sensors have the shortest range of the three and may not detect objects with less reflective surfaces.

So, back to our question above. We now know that because the DX80N9Q45LP is a retroreflective sensor it does require a reflector for proper operation.

For a more thorough examination of the uses and differences between the three main types of photoelectric sensors please visit my source for this FAQ.
Photoelectric Sensor Explained (with Practical Examples) - RealPars