Compact light barriers are powerful through-beam light barriers, consisting of a transmitter and receiver, whitch are characterized by their very small and robust type. No amplifier will be needed different to the high-performance light barriers. The electronic is fully integrated in transmitters and receivers. The system will be used in applications, where no cable between transmitters and receivers are possible. The combination between different transmitters and receivers allows the range up to 40 m or the switching frequencies up to 500 Hz.