Abstract: A portable optical alarm system for area protection containing at least one light-emitting transmitter and a receiver sensing the emitted light is disclosed. The transmitters and receivers of the system form a chain in such a manner that the receiver sensing the light-impulses of the first transmitter is always connected electrically to the following transmitter and the last receiver of the system is connected electrically to the intervening organ and partly to the first transmitter of the system, or the first transmitter of the system is formed as a free-running unit. Transmitters and receivers can be arranged in an optical mutual arrangement where they are arranged in a casing containing the transmitter circuit and the associated battery along with the receiver circuit and the battery belonging thereto.