Fig. 1. Diagram of iterative process

Fig. 2. Original combustion field model. (a) Single Gaussian temperature distribution model; (b) single Gaussian H2O concentration distribution model; (c) step change temperature distribution model; (b) step change H2O concentration distribution model

Fig. 3. Schematic of parallel beam at different projection angles

Fig. 4. Reconstructed combustion field. (a) Single Gaussian temperature distribution; (b) single Gaussian H2O concentration distribution; (c) step change temperature distribution; (d) step change H2O concentration distribution

Fig. 5. Reconstructed temperature error. (a) Single Gaussian distribution model; (b) step change distribution model

Fig. 6. Normalized mean absolute error as a function of lower-state energy. (a) Single Gaussian distribution model; (b) step change distribution model

Fig. 7. Schematic of experimental setup

Fig. 8. Fitting results of two spectral lines when the laser beam passes through the circle point. (a) Line 7185.60 cm-1; (b) line 7454.45 cm-1

Fig. 9. Two-dimensional reconstructed results of the combustion flame. (a) Reconstructed temperature; (b) reconstructed H2O concentration

Fig. 10. Comparison between the reconstructed result of furnace surface temperature and the measured result of thermocouple (y=0)