Fast Simultaneous CO2 Gas Temperature and Concentration Measurements by Quantum Cascade Laser Absorption Spectroscopy

A quantum cascade laser-based sensing technique is presented which allows for in situ high-precision temperature and/or CO2 concentration measurements of gases the room regime with sampling rates up to about 40 kHz. The method based on Boltzmann-like thermally populated fundamental and hot-band rovibrational transitions opposite dependence. Single absorption spectra at 2350 2352 cm−1 are recorded by a nanosecond frequency down chirped IR pulse pulsed distributed feedback laser (intrapulse mode). statistical uncertainty (1σ) measurement within one 1 K can be further reduced 0.1 time averaging over 100 ms. Online breath simulator controlled gas flow were performed demonstrate response-time sensitivity an application-driven test system.