Each infrared-active gas has a specific absorption spectrum and thus an individual fingerprint with characteristic peaks in the infrared spectrum. The higher the concentration of the respective gas, the more infrared radiation it absorbs within its spectrum.In practical applications, an electrically modulated radiation source sends infrared radiation through a measuring cell, the so-called "cuvette". The gas to be measured is introduced into the cuvette and the infrared radiation flows through it. Parts of the radiation are then absorbed by the gas.
At the other end of the cuvette, the reduced light intensity of the radiation is measured by an infrared detector and converted via a measuring amplifier into the corresponding output signals for further processing. An interference filter adapted to the respective gas prevents the detector from responding to wavelengths that are not in the spectrum of the gas to be measured.
Based on the principle, the long-life gas sensors based on the NDIR principle from smartGAS are thus outstanding in terms of selectivity, measurement accuracy and long-term stability. Low detection limits, a very low drift, a wide temperature range as well as a fast response time and extremely low maintenance and service requirements are further important advantages.