Fig. 1. Absorbance of CO₂ and H₂O in the 2‒10 μm band

Fig. 2. Sensor probe structure

Fig. 3. Radiant power of the IR light source and transmission of the detector filter. (a) Radiant power of the light source; (b) transmission of the detector filter

Fig. 4. Calibration experiment system

Fig. 5. Signal absorption versus volume fraction and temperature curves. (a) Volume fraction curves; (b) temperature curves

Fig. 6. Temperature dependence curves. (a) Temperature characteristics of detector; (b) temperature characteristics of light absorption degree

Fig. 7. Volume fraction fitting surface

Fig. 8. Prediction results of the unit surface fitting algorithm. (a) Fitting results for non-characteristic temperature points; (b) fitting results for non-characteristic volume fraction points

Fig. 9. Prediction results of the three prediction methods