“…In recent years, laser absorption spectroscopy technology with its advantages such as high sensitivity, high accuracy, high selectivity, and short response time, has been widely used in environmental pollution monitoring, breathing gas composition analysis and industrial process optimization control, and so on. [1][2][3][4][5][6][7][8][9] At present, more widely used technologies include tunable diode laser absorption spectroscopy (TDLAS), cavity enhanced absorption spectroscopy, cavity ring-down spectroscopy, and photoacoustic spectroscopy. [10][11][12][13][14][15][16][17][18][19] In the TDLAS, the optical multipass absorption cell is one of the key equipment.…”