Non-dispersive infraredspectroscopy

NDIR – operating principle:
A non-dispersive infrared sensor is used to measure molecule concentrations in gases.
Gases have a specific wavelength in the infrared range in which they absorb radiation. The gas to be analyzed is filled into a cuvette of defined length and irradiated with infrared light. The length of the cuvette is selected so that the requirements for the measuring range can be met.
An infrared detector is located at the other end of the cuvette. To prevent the sensor from responding to all wavelengths, a bandpass filter suitable for the respective gas is placed in front of the detector. Only the desired gas absorbs the light of the filtered wavelength and therefore its’ concentration can be determined.