The beam operates totally on the principle of light obscuration working with infrared. The OSI-RI detector is really a put together transmitter/receiver which can be immediately connected to an intelligent detector circuit in LiteSpeed® or CLIP method. Unwanted alarms due to the beam being thoroughly obscured for a brief timeframe https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/