Nondispersive infrared sensor

A nondispersive infrared sensor (or NDIR sensor) is a simple spectroscopic sensor often used as a gas detector. It is non-dispersive in the sense that no dispersive element (e.g., a prism, or diffraction grating, as is often present in other spectrometers) is used to separate (like a monochromator) the broadband light into a narrow spectrum suitable for gas sensing. The majority of NDIR sensors use a broadband lamp source and an optical filter to select a narrow band spectral region that correspond to the absorption region of the gas of interest. In this context, the narrow band can be 50-300 nm bandwidth. Modern NDIR sensors may use microelectromechanical systems (MEMs) or mid IR LED sources, with or without an optical filter.