Many gases absorb infrared light at a unique wavelength (color)
In NDIR sensors the amount of IR light absorbed is proportional to the amount of target gas present
Non-dispersive Infrared Gas Detectors
Measure wavelength-dependent absorption by polyatomic, asymmetric molecules
IR absorption has advantages of high sensitivity, low cross-sensitivity, long life, and resistance to contamination
IR absorption employed in both very highperformance laboratory analyzers and in very lowperformance systems (e.g. inexpensive, nonintrinsically safe hand-held CO2 detectors)
Properties of Light
Light is an electromagnetic field that oscillates as it travels through space:
Electromagnetic radiation spectrum
Infrared (IR) region covers the wavelength range from approx. 0.7
