The development of temperature sensors with ultra-fast response, high sensitivity, and wide range of temperature is of important academic value for the study of flame structure and combustion characteristics under extreme conditions. Recently, tunable diode laser absorption spectroscopy (TDLAS) is developed rapidly as an important means of combustion diagnostics due to its outstanding characteristics, such as non-invasiveness, rapid response, and high realizability. The absorption lines of TDLAS are extended to the mid-infrared region. Two spectral lines of H₂O at center wavelength of 2136.14 and 1874.31 cm^−  1 are used as candidate pair, which provides a wide measuring range (800 to 4000 K) and high-temperature sensitivity (4.55 at 1000 K) sensor for temperature measurement. We used two quantum cascade lasers with wavelength of 4.68 and 5.34 μm to scan the selected line pair of H₂O rapidly in the combustion environment and obtained the temperature information of the combustion field. Our work provides a good solution for the temperature measurement of extreme combustion environment with ultra-fast response, high sensitivity, and wide temperature range.

Nitrogen dioxide (NO₂) absorption correction of the sulfur dioxide (SO₂) camera was demonstrated for the first time. The key to improving the measurement accuracy is to combine a differential optical absorption spectroscopy (DOAS) instrument with the SO₂ camera for the real-time NO₂ absorption correction and aerosol scattering correction. This method performs NO₂ absorption correction by the correlation between the NO₂ column density measurement of the DOAS and the NO₂ optical depth of the corresponding channel from the SO₂ camera at a narrow wavelength window around 310 and 310 nm. The error of correction method is estimated through comparison with only using the second channel of the traditional SO₂ camera to correct for aerosol scattering and it can be reduced by 11.3% after NO₂ absorption corrections. We validate the correction method through experiments and demonstrate it to be of greatly improved accuracy. The result shows that the ultraviolet (UV) SO₂ camera system with NO₂ absorption corrections appears to have great application prospects as a technology for visualized real-time monitoring of SO₂ emissions.