Fig. 1. CO₂ absorption spectra with wave numbers of 4978.202 cm⁻¹

Fig. 2. Schematic diagram of TDLAS trace amount of CO₂ detection system

Fig. 3. Comparison of the second harmonic collected by the system before and after filtering by Kalman-wavelet analysis algorithm

Fig. 4. Diagram of 50-8000 ppmv CO₂ concentration calibration

Fig. 5. Error result of Kalman-wavelet analysis algorithm

Fig. 6. Comparison experiment of CO₂ detection stability of the system at 4000 ppmv concentration

Fig. 7. Allan deviation method detection limit