working principle: An oxygen analyser contains an oxygen sensor which reacts with the oxygen in the atmosphere or gas stream. In the simplest form a TDL analyzer consists of a laser that produces infrared light, optical lenses to focus the laser light through the gas to be measured and then on to a detector, the detector, and electronics that control the laser and translate the detector signal into a signal representing the gas concentration.

The oxygen sensor will produce a small electrical current that is proportional to level of oxygen it is reacting with.