An infrared gas analyzer for measuring at least one component gas of a sample gas mixture. A beam of infrared radiation is periodically interrupted and propagated through a measuring cell through which the sample gas mixture flows. The infrared radiation beam is divided into a reference ray which is...http://www.google.com.au/patents/US4468561?utm_source=gb-gplus-sharePatent US4468561 - Nondispersive infrared gas analyzer
