RAE (2014) Theory and Operation of NDIR Sensors

The MultiRAE IR monitor uses an NDIR (non-dispersive infrared absorbance) sensor to monitor CO2. Most molecules can absorb infrared light, causing them to bend, stretch or twist. The amount of IR light absorbed is proportional to the concentration. The energy of the photons is not enough to cause ionization, and thus the detection principle is very different from that of a photoionization detector (PID). Ultimately, the energy is converted to kinetic energy, causing the molecules to speed up and thus heat the gas. A familiar IR light source is an incandescent household bulb. Each molecule absorbs infrared light at wavelengths representative of the types of bonds present. t ags: IR, NDIR

RAE-2014-Theory-and-Operation-of-NDIR-Sensors.pdf

RAE (2014) Theory and Operation of NDIR Sensors
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