Q: Do photoelectric sensors need to be equipped with reflectors?

I'm often asked whether certain sensors, such as the DX80N9Q45LP from Banner Engineering , require a reflector to operate.

Photoelectric sensors use light to detect the presence or absence of objects within the sensor's field of view. Whether your sensor requires a reflector depends on the type of sensor you want to purchase.

There are three main types of photoelectric sensors:

• Through-Beam Sensors : Through-beam sensors use a separate transmitter and receiver. The transmitter sends a beam of light directly to the receiver, typically creating a normally closed circuit. If the beam is blocked by an object, the circuit switches to a normally open circuit. Through-beam sensors can detect objects at greater distances but require precise placement and alignment to ensure proper operation. This type of sensor may not detect transparent objects.

• Retroreflective Sensors : Similar to through-beam sensors, these sensors use a transmitter and receiver to send and detect light beams, but both are housed within the same unit. To properly detect objects, retroreflective sensors require a reflector mounted directly opposite the sensor. Similar to through-beam sensors, these sensors typically have a normally closed circuit that switches to a normally open circuit when an object is detected. Retroreflective sensors have a shorter range than through-beam sensors and may not detect shiny objects, as these reflect light like a reflector.

• Diffused Sensors : Similar to retroreflective sensors, diffused sensors combine the transmitter and receiver within the same unit. However, rather than relying on a reflector to bounce light back to the sensor, they use the object itself. Their circuitry generally behaves the same as the other two sensor types. Because they use the object to return light, diffused sensors have the shortest range of the three and may not detect objects with less reflective surfaces.

Back to our question above. We now know that since the DX80N9Q45LP is a retroreflective sensor, it does require a reflector to work properly.