Infrared Sensors are the sensors that utilize Infrared waves to detect motion. Infrared sensors are used for various purposes but mainly they are used in security solutions installed at residential and commercial. Infrared sensors are of two types i.e. Active Infrared Sensors and Passive Infrared Sensors. The Infrared beam sensors or Photobeam sensors are the ones that use Active Infrared (AIR) for detecting the motion and thus we are here with a complete guide on AIR sensors only. Active Infrared Sensors: AIR sensors are the type of sensors that emit infrared waves through a transmitter which gets received by a receiver. Any alteration in the path of the waves indicates the detection of an object.