The Optical Barrier V3 from Delta emit visible and modulate laser beam by the diode and reflects is back using the prism reflector position opposite to the sensor. The detected photodiode then creates a signal to the processing electronics. The presence of the product is detected depending on whether the beam is blocked or not. The beam endures ambient light because of its beam modulation, special optical filter, and automatic correction. It encased in a cast aluminum case with air purged hood for protecting the lens and with water-cooling plate.