The laser scanner inspects a field area of max. 30 x 30 ft. The scanning area can be divided up into one safety field and one opening field. Vehicles and persons are detected within the safety f ield; only very small objects (such as pendulum supports) are cut out. Depending on the selected settings, the barrier only opens when a vehicle is detected, not persons. The barriers then only close when nobody is present within the safety field. The laser scanner generates four overlying beams, effectively suppressing any interference.