The beam operates primarily on the principle of sunshine obscuration making use of infrared. The OSI-RI detector is a merged transmitter/receiver which can be directly linked to an intelligent detector circuit in LiteSpeed® or CLIP manner. Undesirable alarms mainly because of the beam becoming absolutely obscured for a brief time https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/