Our light curtains for industrial use and elevators monitor a defined control area with several invisible, infrared light beams. The through beam light curtain systems consist of a transmitter and a receiver strip made of anodized aluminium. This is the same as having several through beam light barriers with linked output signals. If a random light beam is interrupted between the transmitter and the receiver strip, the output of the evaluation electronics is activated. Depending on the light curtain type, the evaluation electronics are either integrated into the light curtain strips or operate as an external amplifier in a separate casing.