Recent progress on laser absorption spectroscopy for determination of gaseous chemical species

Laser absorption spectroscopy combined with spectral analysis has been extensively investigated in detection and measurements of gas samples because of their broad applicability for measuring more than one hundred species, such as O₂, CO₂, H₂O, HCl, NH₃, NO_x, and hydrocarbons. Recently, real-time detection and measurements of gas samples based on laser absorption spectroscopy have attracted considerable interest from various fields owing to their performance of robustness, fast response speed, high sensitivity, and good precision. Here, we review the commonly used infrared laser absorption spectroscopy techniques for real-time measurements and the significant optical equipment utilized in measuring systems. Then, we discuss practical applications based on infrared laser absorption spectroscopy which require real-time determination of gas component concentrations, including atmospheric environment monitoring, breath analysis, combustion diagnostics, and industrial applications. Finally, perspectives of real-time determination of gas component concentrations based on infrared laser absorption spectroscopy are presented.