Hyperspectral absorption of CO in the near infrared band at room temperature

As an important medial product in the combustion process of carbon-based compounds, CO serves as one of the preferable candidates for combustion diagnosis in absorption spectrum. So far, most of researches have focused on the conventional one-line or dual-line technique, which requires a number of beam projections for two-dimension (2D) tomography of combustion field. Hyperspectral absorption spectroscopy enables continuous acquisition of absorption information over a whole absorption band, rather than one or two discrete absorption lines, demonstrating remarkable advantage over the traditional one-line and dual-line techniques. Hyperspectral absorption spectroscopy can not only reduce the system complexity with limited projections for high spatial resolution 2D tomography, but also improve the system applicability by refining the measurement robustness. However, up to now, little attention has been paid to hyperspectral absorption of CO. Here, by using a wideband tunable laser source around 1.5 mu m, experiments are conducted at room temperature to investigate the hyperspectral absorption characteristics of CO in the near infrared band. Absorptions under different pressure conditions are compared with each other. And, the measured results are consistent with the HITRAN2016 database. With the measured hyperspectral absorption information in the 1565-1570 nm range, temperature and mole fraction of CO are derived by the first derivative method. Despite the distortion of the recorded absorption peaks, accurate results are obtained with measurement errors within 5% for both temperature and mole fraction, thereby validating the reliability of hyperspectral absorption technique for CO. And, this research is instructive for future 2D tomography of combustion fields based on hyperspectral absorption of CO.